Questions for the City
1. Northbound Dubuque street was just inches above the river in Spring 2008 when the flow was 10,000 CFS. Elevating the northbound lane could allow the peak "normal flood" flow to be increased. What other barriers are there in our metro area to increasing the peak "normal spring flood" to 12,000 CFS? We base this question on the expectation that such a release rate, last spring, could have allowed a more significant drawdown of the reservoir prior to the June flood, thereby creating capacity that could have reduced the peak flood flow.
2. We note that the federal buyout rules are rather rigid in forbidding flood control measures on land incorporated into the buyout. How much flexibility does the city have to buy land, redivide it, and then resell parts to the federal buyout program? This could allow reconfiguration of land parcels so that a coherent (straight, as opposed to zigzag) flood-control system could be created behind the line of any Federal buyout.
3. Can the city build a second exit from the neighborhood? This is needed because whatever flood barrier that is put in place could be overtopped, and if that happens, we want a better evacuation plan -- this is something the city knew when the neighborhood was built.
4. Can the City build a flood warning post or bulletin board to be placed at in the 1% and 0.2% flood zones throughout the city?
5. Can the city retro-fit one-way valves in all storm drains that drain areas in the 1% and 0.2% flood risk zones?
6. When will Iowa City’s Hazard Mitigation Plan (that the city needs to comply with the National Flood Insurance Program) be ready? Will there be an opportunity for public input?
7. What is the City going to do for PVT in Spring 2009 in case it floods?
8. Would the City be willing to participate in a regional flood mitigation plan (along with the University of Iowa, City of Coralville, city of North Liberty, Iowa Department of Natural Resources, Army Corps of Engineers, and Johnson County)?
9. Would the City consider modifying the current zoning and subdivision ordinances to ensure future developments are at lower flood risk?
10. Would the City be willing to work with the Johnson County Conservation Board to acquire land using the recently approved conservation bond funds to acquire land in PVT to expand City Park?
11. Does the City have a well-developed evacuation plan to be used if flooding threatens any neighborhood in Iowa City in the future?
12. Would the City be willing to buy farmland to the south of the city to help with flood control? We have been informed that preventing flooding of farmland south of the city is a significant reason for lower rate of discharge from the dam. Buying some of this farmland may allow for higher discharge rates earlier in Spring and Summe
Wednesday, January 21, 2009
Tuesday, January 20, 2009
PVT and City Meeting Thursday 1/22 agenda
Dear All:
Here’s the agenda for the meeting with the City this Thursday at 7:00pm at the IC Water Treatment Plant. Several of you have sent in “questions for the city” to the block captains or me already. If anyone else has questions, please email them to Roberta, Louise, Mary Strum or Deb Knapp by the end of the day. Thanks. -- Jerry
• Community Wide Flood Recovery
• Iowa City Flood Mitigation Strategies
• Coordination of Area Wide Flood Mitigation Strategies
• Floodplain Mapping
• Parkview Terrace Neighborhood Options
• What’s Next?
Here’s the agenda for the meeting with the City this Thursday at 7:00pm at the IC Water Treatment Plant. Several of you have sent in “questions for the city” to the block captains or me already. If anyone else has questions, please email them to Roberta, Louise, Mary Strum or Deb Knapp by the end of the day. Thanks. -- Jerry
• Community Wide Flood Recovery
• Iowa City Flood Mitigation Strategies
• Coordination of Area Wide Flood Mitigation Strategies
• Floodplain Mapping
• Parkview Terrace Neighborhood Options
• What’s Next?
Sunday, January 18, 2009
Give land back to the Iowa River
I'm reposting this as the links are broken on the original post. I'll try to cut and paste newspaper articles as they archive them and then charge for a reprint. Sorry for the inconvience.
Give land back to the Iowa River
Before the Iowa River takes back Parkview Terrace -- yet again
Marc Linder • Guest Opinion • July 12, 2008
A preliminary historical sketch of how the Normandy neighborhood came to be developed may help explain why the Federal Emergency Management Agency, the state of Iowa and Iowa City should buy out the homeowners and use the land to create natural grasslands or wetlands.
Pre-development ownership
During the 1950s, before the Coralville Dam was opened, what is now Parkview Terrace was owned by an Iowa City automobile franchisee, Clarence Beck, who rented the land out to be farmed as cornfields, on which lakes formed during spring flooding.
Not until the elections of 1955 did the city annex the land, which had been part of unincorporated Johnson County (the motivation for this annexation, like that for the purchase of the land on the town's outskirts, presumably having been the prospect of development).
Then in January 1956, Beck sold the land to Leonard Kaplan, an owner of movie theaters in Eastern Iowa, who in turn sold it to a group including himself; Louis Shulman, a well-known local lawyer; Sam Robinson, secretary-treasurer of a local oil and gas company -- all of whom had previously cooperated on other business deals; and Nilla Jensen, widow of Viggo Jensen, who owned a construction company.
After several further sales during the next year or so, the land wound up in the possession of the Jensen Land Development Corporation, Kaplan, Shulman and Robinson.
Planning and zoning concerns
By 1958-59, as the Coralville Dam was nearing completion, this group sought the City Council's approval of the subdivision it wanted to develop. But on Oct. 7, 1958, the Iowa City Planning and Zoning Commission adopted a resolution on the zoning of floodplain areas that underscored how flooding would lead to the possible loss of life and property, pollution of waters and hazards caused by broken sewer, water supply and electrical power lines.
Because such a disaster would require "public and private agencies ... to rescue and retrieve life and property and the economic loss must be shared by many people not responsible, and public funds must be expended to repair, restore or rehabilitate streets, sewers and bridges," the commission recommended that the council restrict land uses in a "Special Flood Plain Zone."
Six days later, the commission explained to the mayor and City Council that such land use was causing it "considerable anxiety." The commission wrote that the council was "being asked to consider a change of zoning of an area adjacent to the Iowa River that will be flooded in the future." The commission pointed out that flooding was a "very old" problem in Iowa City and one the new dam could not eliminate completely: "(The) engineering data show that certain conditions of natural runoff in the drainage basin will produce floods beyond the capacity and control of the reservoir."
The commission warned the council that a "degree of complacency has developed in Iowa City by a lack of understanding of the flood history of the Iowa River and the amount of control possible by the Coralville dam." Seeking to avoid being "charged with a culpable lack of foresight if we did not call to your attention that certain hazards yet remain," the commission emphasized that the city's growth and "the urge to use vacant land of close proximity to the university makes the old problem a critical one for solution in the near future."
'Not suitable for residential development'
On June 12, 1959, the commission wrote to the council again about the proposed Parkview Terrace subdivision, communicating the contents of a motion passed at its last meeting: "In view of the location of the proposed sub-division, on the flood plain of the Iowa River with its vulnerability to high ground water levels, wash from surrounding bluffs, and even possible flooding on rare occasions, it is believed that this area is not suitable for residential development."
It should be emphasized that the commission was not composed of a bunch of anti-progress yahoos. Its chairman and key figure, Joseph Howe, was a long-time professor and chairman of hydraulics and mechanics at UI who had professionally studied the Iowa River. The vice chairman was Allen Tester, a UI professor of geology. And long-time State Geologist H. Garland Hershey was also a member. Other members included Charles Barker, Richard Feddersen, James Pearson and Sam Whiting.
All of the commission members, including two real estate businessmen, opposed the building plans and supported using the land for City Park or some similar project. Nevertheless, four days later the City Council unanimously approved the plat and subdivision.
The council's rejection of the commission's report has to been seen in the context of various developmental pressures, sheer boosterism and perhaps the councilors' personal denial of the possibility that the water could ever go over the spillway.
Intriguingly, less than a month later the City Council announced that it deemed it advisable to buy from the same owners 27.1 acres contiguous to the new subdivision in order to expand City Park westward.
Later that summer the council bought the land at what was apparently a low $500 an acre.
What today's council should do
Iowa City's decision to permit the building of a residential neighborhood along the river in the late 1950s was an urban planning mistake that half a century later has bequeathed catastrophic consequences to those living there.
To rectify their predecessors' distorted judgment, the mayor and the City Council should now do everything in their power to promote a buyout and to return the land to the wetlands that it has always been.
Marc Linder, an Iowa City resident since before the 1993 flood, hopes that this tentative sketch will prompt both those with personal recollections of the 1950s to come forward with additional information and others to dig deeper in documentary sources.
Give land back to the Iowa River
Before the Iowa River takes back Parkview Terrace -- yet again
Marc Linder • Guest Opinion • July 12, 2008
A preliminary historical sketch of how the Normandy neighborhood came to be developed may help explain why the Federal Emergency Management Agency, the state of Iowa and Iowa City should buy out the homeowners and use the land to create natural grasslands or wetlands.
Pre-development ownership
During the 1950s, before the Coralville Dam was opened, what is now Parkview Terrace was owned by an Iowa City automobile franchisee, Clarence Beck, who rented the land out to be farmed as cornfields, on which lakes formed during spring flooding.
Not until the elections of 1955 did the city annex the land, which had been part of unincorporated Johnson County (the motivation for this annexation, like that for the purchase of the land on the town's outskirts, presumably having been the prospect of development).
Then in January 1956, Beck sold the land to Leonard Kaplan, an owner of movie theaters in Eastern Iowa, who in turn sold it to a group including himself; Louis Shulman, a well-known local lawyer; Sam Robinson, secretary-treasurer of a local oil and gas company -- all of whom had previously cooperated on other business deals; and Nilla Jensen, widow of Viggo Jensen, who owned a construction company.
After several further sales during the next year or so, the land wound up in the possession of the Jensen Land Development Corporation, Kaplan, Shulman and Robinson.
Planning and zoning concerns
By 1958-59, as the Coralville Dam was nearing completion, this group sought the City Council's approval of the subdivision it wanted to develop. But on Oct. 7, 1958, the Iowa City Planning and Zoning Commission adopted a resolution on the zoning of floodplain areas that underscored how flooding would lead to the possible loss of life and property, pollution of waters and hazards caused by broken sewer, water supply and electrical power lines.
Because such a disaster would require "public and private agencies ... to rescue and retrieve life and property and the economic loss must be shared by many people not responsible, and public funds must be expended to repair, restore or rehabilitate streets, sewers and bridges," the commission recommended that the council restrict land uses in a "Special Flood Plain Zone."
Six days later, the commission explained to the mayor and City Council that such land use was causing it "considerable anxiety." The commission wrote that the council was "being asked to consider a change of zoning of an area adjacent to the Iowa River that will be flooded in the future." The commission pointed out that flooding was a "very old" problem in Iowa City and one the new dam could not eliminate completely: "(The) engineering data show that certain conditions of natural runoff in the drainage basin will produce floods beyond the capacity and control of the reservoir."
The commission warned the council that a "degree of complacency has developed in Iowa City by a lack of understanding of the flood history of the Iowa River and the amount of control possible by the Coralville dam." Seeking to avoid being "charged with a culpable lack of foresight if we did not call to your attention that certain hazards yet remain," the commission emphasized that the city's growth and "the urge to use vacant land of close proximity to the university makes the old problem a critical one for solution in the near future."
'Not suitable for residential development'
On June 12, 1959, the commission wrote to the council again about the proposed Parkview Terrace subdivision, communicating the contents of a motion passed at its last meeting: "In view of the location of the proposed sub-division, on the flood plain of the Iowa River with its vulnerability to high ground water levels, wash from surrounding bluffs, and even possible flooding on rare occasions, it is believed that this area is not suitable for residential development."
It should be emphasized that the commission was not composed of a bunch of anti-progress yahoos. Its chairman and key figure, Joseph Howe, was a long-time professor and chairman of hydraulics and mechanics at UI who had professionally studied the Iowa River. The vice chairman was Allen Tester, a UI professor of geology. And long-time State Geologist H. Garland Hershey was also a member. Other members included Charles Barker, Richard Feddersen, James Pearson and Sam Whiting.
All of the commission members, including two real estate businessmen, opposed the building plans and supported using the land for City Park or some similar project. Nevertheless, four days later the City Council unanimously approved the plat and subdivision.
The council's rejection of the commission's report has to been seen in the context of various developmental pressures, sheer boosterism and perhaps the councilors' personal denial of the possibility that the water could ever go over the spillway.
Intriguingly, less than a month later the City Council announced that it deemed it advisable to buy from the same owners 27.1 acres contiguous to the new subdivision in order to expand City Park westward.
Later that summer the council bought the land at what was apparently a low $500 an acre.
What today's council should do
Iowa City's decision to permit the building of a residential neighborhood along the river in the late 1950s was an urban planning mistake that half a century later has bequeathed catastrophic consequences to those living there.
To rectify their predecessors' distorted judgment, the mayor and the City Council should now do everything in their power to promote a buyout and to return the land to the wetlands that it has always been.
Marc Linder, an Iowa City resident since before the 1993 flood, hopes that this tentative sketch will prompt both those with personal recollections of the 1950s to come forward with additional information and others to dig deeper in documentary sources.
Saturday, January 17, 2009
City Meeting Flood Mitigation Jan 22 7 pm
City presents its options for flood mitigation
Location: City’s Water Treatment Plant (80 Stephen Atkins Drive - near I-80/N. Dubuque St.).
Time: Thursday, January 22 at 7:00 PM
Check the post card sent to your address
Location: City’s Water Treatment Plant (80 Stephen Atkins Drive - near I-80/N. Dubuque St.).
Time: Thursday, January 22 at 7:00 PM
Check the post card sent to your address
Friday, January 16, 2009
Mail Delivery
All, Scott - our faithful Mail Carrier in PVT - apparently fell and broke his ankle and we have a substitute carrier.
I thought when my temporary forward expired the mail service would return delivery to my house, but this is not the case. It's either being held by the post master at the west side annex or being returned to the sender.
You must file another temporary or permanent address change to get your mail.
You can call the West Side Annex of the post office to determine your mail delivery status at 337-8881.
I thought when my temporary forward expired the mail service would return delivery to my house, but this is not the case. It's either being held by the post master at the west side annex or being returned to the sender.
You must file another temporary or permanent address change to get your mail.
You can call the West Side Annex of the post office to determine your mail delivery status at 337-8881.
Wednesday, January 14, 2009
General Stuff
Yahoo - the streets in PVT are really plowed - seems like this is the 1st time in two years. Not sure how it happened, but it's great!
Green Shirts have said they have not seen many flood victims. It's a painless, 1/2 hour interview and I hope the information they gather will help provide our neighborhood with the assistance it needs to be rebuilt. Please stop by at the locations listed on this link. Green Shirt Announcement
Snow Fall Comparison
Iowa City tied right now with last year at 22.9 inches. The bad news is all of the cities north, i.e. Dubuque, Waterloo, etc are substantially ahead of last year. Hope the Corps opens the gates earlier and lets the rez go back to 670 feet so we have a flood cushion.
Green Shirts have said they have not seen many flood victims. It's a painless, 1/2 hour interview and I hope the information they gather will help provide our neighborhood with the assistance it needs to be rebuilt. Please stop by at the locations listed on this link. Green Shirt Announcement
Snow Fall Comparison
Iowa City tied right now with last year at 22.9 inches. The bad news is all of the cities north, i.e. Dubuque, Waterloo, etc are substantially ahead of last year. Hope the Corps opens the gates earlier and lets the rez go back to 670 feet so we have a flood cushion.
Monday, January 12, 2009
Lessons from the Flood--Collaborating in a Crisis
You're invited to a public program!
Lessons from the Flood--Collaborating in a Crisis
7 p.m. Thursday, January 15
Iowa City Public Library, Room A
Guest Lecturer Iowa City Manager Michael Lombardo"The View from City Hall"
Panelists Barbara Eckstein, UI Associate Provost and Professor of English"Before the Flood: An Endangered River Runs Through Us"
Gregg Oden, UI Professor of Psychology and Computer Science"After the Flood: Co-Chairing the UI Flood Mitigation Task Force"A reception follows at the Englert Theatre.
Presented by the Graduate Institute on Public Engagement and the Academy.
Sponsored by the UI Obermann Center for Advanced Studies and the UI Graduate College. Co-sponsored by the UI Center for Teaching, UI Civic Engagement Program, the City of Iowa City, the Women's Resource and Action Center and the UI Associate Provost for Diversity.
For more information call the Obermann Center for Advanced Studies 335-4034 or visit http://www.uiowa.edu/obermann/about/NewsReleaseLessonsFromtheFlood.pdfIf you require an accommodation in order to participate in this program, please contact Neda Barrett in advance at 319-335-4034.
Lessons from the Flood--Collaborating in a Crisis
7 p.m. Thursday, January 15
Iowa City Public Library, Room A
Guest Lecturer Iowa City Manager Michael Lombardo"The View from City Hall"
Panelists Barbara Eckstein, UI Associate Provost and Professor of English"Before the Flood: An Endangered River Runs Through Us"
Gregg Oden, UI Professor of Psychology and Computer Science"After the Flood: Co-Chairing the UI Flood Mitigation Task Force"A reception follows at the Englert Theatre.
Presented by the Graduate Institute on Public Engagement and the Academy.
Sponsored by the UI Obermann Center for Advanced Studies and the UI Graduate College. Co-sponsored by the UI Center for Teaching, UI Civic Engagement Program, the City of Iowa City, the Women's Resource and Action Center and the UI Associate Provost for Diversity.
For more information call the Obermann Center for Advanced Studies 335-4034 or visit http://www.uiowa.edu/obermann/about/NewsReleaseLessonsFromtheFlood.pdfIf you require an accommodation in order to participate in this program, please contact Neda Barrett in advance at 319-335-4034.
Sunday, January 11, 2009
News Stories on Meetings
Gosh - here are the stories.
Corps talks about role during flood
Official says he wouldn't live in floodplain
http://www.press-citizen.com/article/20090111/NEWS01/901110322/1079/news01
Corps reviews Coralville Dam's role in flood
http://www.gazetteonline.com/apps/pbcs.dll/article?AID=/20090110/NEWS/701109940/1006
Corps talks about role during flood
Official says he wouldn't live in floodplain
http://www.press-citizen.com/article/20090111/NEWS01/901110322/1079/news01
Corps reviews Coralville Dam's role in flood
http://www.gazetteonline.com/apps/pbcs.dll/article?AID=/20090110/NEWS/701109940/1006
Friday, January 9, 2009
Corps answers to our Questions - Still leaves questions
Park View Terrace Questions for Army Corps of Engineers (Rock Island)
Friday, January 09, 2009
1. What is the Corps of Engineers doing/going-to-do to minimize the chances of another flood in PVT in Spring 2009?
RESPONSE: Flooding in Park View Terrace will continue to be a possibility dependent on snowmelt and rainfall amounts within the 3,115 square-mile watershed flowing into Coralville Reservoir and below the Reservoir.
Coralville Reservoir will always reduce peak flows on the Iowa River below the reservoir, regardless of the size of a flood, which will minimize flooding in PVT, Iowa City and areas downstream of the reservoir. The highest outflow during any given event will always be less than the peak inflow, even when water is well over the top of the spillway. The dam stores water when its pool elevation is increasing, meaning that the inflow is greater than the outflow. A few days after the peak inflow has occurred, the pool elevation will crest when the inflow equals what is being released in the outflow.
In 2008, we coordinated releases from Coralville Reservoir with Iowa City officials to provide ample time for emergency responders to remove property from anticipated flood areas, sandbag city infrastructure and personal property, and to provide the public with the maximum amount of time possible to implement flood protection for their personal property or evacuate if needed. During the 2008 flood, Coralville Reservoir successfully reduced flows on the Iowa River below the dam by 17,500 cubic feet per second, which reduced the River’s flood stage by 5.0 feet.
Prior to, and during, the 2008 flood, the Corps deployed flood-area engineers to Iowa City, Des Moines, Cedar Rapids, the Quad Cities, and throughout the state of Iowa advising emergency officials of the National Weather Service flood forecasts and our operations of reservoirs.
We will implement all of these actions again in 2009 if needed.
In late winter and early spring, the Corps will again work closely with the National Weather Service and the U.S. Geological Survey to monitor ground conditions, snowmelt and flood potential. During that time, we will maintain the Reservoir according to its approved Regulation Manual.
In the spring, the reservoir pool levels are maintained to allow for snow melt runoff, and for predicted and actual rainfall, to prevent downstream flooding. The pool levels will occasionally fluctuate to prepare for such runoff and for National Weather Service rainfall predictions. Pool levels are also maintained to ensure minimal bank erosion which contributes to sedimentation on the reservoir floor, adequate summer water supply, continued river flow below the reservoir, conservation purposes, and for Iowa and surrounding areas recreational opportunities.
During flood control operations, weather parameters are evaluated on an hourly basis to consider rainfall in the drainage area above the reservoirs; rainfall below the reservoirs; and National Weather Service rainfall predictions over a 24-hour period. This information is used by the Corps to anticipate inflows to the reservoirs and make adjustments to release rates to conserve flood storage capacity and minimize both up-river and down-river flooding.
2. Instead of waiting until the level at the reservoir reaches 700 feet to get active about moving water out of it, why not move it out sooner, say, at about 680 feet? It seems like waiting that long is almost too late and if any unforeseen rain comes in from the north, there isn’t enough wiggle room. Is there a possibility of changing the outflow numbers?
RESPONSE: As you know, the Coralville Reservoir is operated according to its approved Regulation Manual. All of our reservoirs are operated to conform to a strict, standard regulation plan that is coordinated by the Corps of Engineers for review and approval by local, state and federal agencies with water resources responsibilities. This standard includes regulation of releases during flood events. The latest revision occurred in January 2001 and was subject to public review and comment. A copy of the manual is available on the CD-ROM provided at this meeting (Note: The manual on the CD-ROM does not include plates and diagrams of the reservoir for security purposes).
Outflow modifications during flood emergencies are considered at the request of public officials. If outflow modifications are warranted, approval from our higher headquarters is required. We do not modify outflows during normal operating conditions.
To modify outflows on a permanent basis would require a revision of Coralville Reservoir’s operations manual. Revising the manual requires a request from the state of Iowa and a cost-sharing of 50 percent of the study. The Corps would also require appropriations from Congress for our cost share of the study. The cost of the study would have to be determined once the scope of the study was developed.
3. What is the minimum level of water that must be retained in the Coralville reservoir for:
a) protection of wildlife,
b) move sewage downstream, and
c) for recreational boating?
RESPONSE: These issues were considered as well as others when the following lake levels were determined, but there is no specific level for each.
The current approved operating levels are essential in order to protect fisheries within the reservoir and provide a minimum 150 cubic feet per second outflow as required by the state to meet downstream water quality targets during droughts. The current approved operating pool levels are:
15 February – 20 March: 683 to 679 National Geodetic Vertical Datum (NGVD) *
20 March – 20 May Hold @ 679 NGVD *
20 May – 15 September Hold @ 683 NGVD
15 September – 15 December Hold 683 to 686 NGVD **
15 December – 15 February Hold @ 683 NGVD
Notes:
* Variable draw down based on snow cover, ice, and 30-day climatic conditions coordinated with IDNR
** Dates and elevation of fall pool raise coordinated with the IDNR
4. Communications and the Corps
a) How does the Corps coordinate communication in times of flooding? Does it give directives for local councils regarding mandatory evacuation and other actions, or does it leave all these decisions to each city and township? (Could this info be shown on a diagram or in a written document).
RESPONSE: During periods of predicted and actual flooding, the Corps dispatches flood-area engineers to communities that may be affected by, or are affected by, flooding to alert communities to the flood projections and to provide technical flood-fighting support. Our Emergency Operations Center at Rock Island, Illinois, is activated and we are in regular communication with officials from affected communities, State emergency operations staff, and the Department of Homeland Security.
In addition, Corps water management and reservoir staff conducted daily teleconferences each morning (and sometimes more frequently)with Iowa City, the University of Iowa, the city of Coralville, and the Iowa Department of Transportation to aid them in the their decision-making process with regard to flood fighting, evacuations and road closures. This process will be followed during all future floods.
The Corps can only advise officials of what might happen and provide our professional opinion of a flooding situation. We do not have the authority to require evacuations or any other mandatory actions from local officials.
b) Will the Corps be communicating with Iowa City in the future to advise us of high water and how it will impact Park View Terrace?
RESPONSE: As in the past, and during the 2008 flood, if flooding is a concern, the Corps will dispatch flood-area engineers to Iowa City to ensure communities are aware of flood impacts and to provide technical flood-fighting support as needed. The Corps will continue to advise city officials of what might happen and provide our professional opinion of a flood situation.
Due to lessons learned during the 1993 and subsequent floods, and improved technology, we believe we had much better communication with affected communities during the 2008 flood. This will only continue to improve with additional lessons learned and better technology.
c) We have found the Corps forecasts of flood levels at the hydraulics lab gauging station less than helpful. The problem is that the gauging station is in a choke-point in the river valley and it is immediately downstream of a dam, so a 4-foot rise there does not translate to a 4-foot rise in areas where the floodplain is wider and dams are distant (as in our neighborhood). Could the Corps offer river-level forecasts for developed areas along the river such as ours?
RESPONSE: The Corps does not forecast river levels for Iowa City as the National Weather Service (NWS) is the agency responsible for issuing all weather and river forecasts to the public. The Corps does provide a 7-day outflow forecast from Coralville Reservoir to the NWS. The NWS incorporates the outflow information along with flows on Rapid Creek and Clear Creek to develop a river forecast for Iowa City.
The stream gaging network in place today is a mix of gages funded by the Corps, the USGS and other cooperators. Each agency operates and maintains their gages as resources allow. Together, the network provides the necessary data for the NWS to model stream and river conditions to provide the best-available river level forecasts. These forecasts are available on the internet @ http://www.nws.noaa.gov/ and at www.rivergages.com.
While additional gaging stations along rivers and tributaries are always useful, the Corps is not funded at this time to install and maintain additional gauges. However, it should be noted that the USGS gage at the hydraulics lab has a long period of record and is an excellent location with regard to maintaining a stable stage versus flow relationship which is essential to providing an accurate forecast. In lieu of installation of an additional gage, Park View residents can relate actual flooding that has occurred on their property historically to Iowa City gage readings.
5. Do Corps personnel ever come "in person" checking rivers downstream of Coralville Reservoir? Because it was clear for us riverside residents that river was very high since March 2008, and then, once or twice, it went down almost eerie low in April, then the flood came. Something was amiss, something that the computers probably got wrong, but human eyes could easily recognize.
RESPONSE: The low river levels that were observed in April were due to a temporary outflow reduction required to reduce flooding downstream at Wapello and Burlington and not a gage malfunction. If a gage is not functioning properly, the Corps and USGS deploy technicians that will inspect the gage in person and make any repairs needed.
The Corps of Engineers relies on our system of gages to operate all of our reservoirs, including the Coralville Reservoir. Gage data is provided via satellite to provide real-time flow information which allows us to operate our reservoirs to the best of our abilities.
6. Since Hurricane Katrina levee collapse and the Minneapolis I35 bridge collapse, we are hearing a lot about many US infrastructure failures -- out of date facilities, poor maintenance, and recurring human errors. Therefore,
a) What, frankly, is the state of the Coralville Dam currently?
RESPONSE: The U.S. Army Corps of Engineer’s dams are managed through the Dam Safety Program, which includes routine inspections and continual evaluations in accordance with the Federal Guidelines for Dam Safety issued in 1979 and 2004. The primary objective of the Dam Safety Program is to improve public safety by ensuring that Corps-owned and operated dams are structurally sound and operated according to the intended purpose; and that risks to the public are minimized.
There are no structural or other operating concerns at Coralville Reservoir. The Reservoir received a thorough inspection in August 2008 following the flood. Prior to that in August 2006, the Screening Risk Portfolio Analysis team that assesses dam safety rated Coralville Dam as being in good overall condition.
Corps dams are designed to withstand enormous pressures and water levels. All Corps reservoirs are built to stringent engineering standards to ensure they will withstand record flood events. Each reservoir is under observation to ensure its structural integrity and safety.
Reservoirs are also visually inspected on a regular basis under normal operating conditions and are visually inspected several times a day during flood events. Minor erosion adjacent to the outlet works can occur during major flood events but does not impair the structural integrity of the dam. The dam was thoroughly inspected after 1993 and 2008 and no movement or deterioration has been noted.
b) What is the REAL lifetime of the reservoir (we've heard everything from 50 years to 100 years)? What are the factors for determining the reservoir's lifetime, how does silting-in factor? What capacity has been lost due to silting-in and how does that relate to water upstream and the altered retention capability of the reservoir.
RESPONSE: Any sedimentation below the conservation pool does not impact flood storage. As an example, take two cups of equal size. One cup is half full of water and the other cup is half full of saturated silt, both cups still have the same amount of water storage volume left in them.
Sedimentation impacts are mostly recreational and environmental within the conservation pool. While the deposition of sediment continues to occur, the majority of sediment deposition has been in the conservation pool. For example, Coralville reservoir still retains approximately 89% of its original flood storage capacity, in comparison to only 55 percent of its original conservation storage capacity. Major flood events deposit sediment in the flood control pool, but on a day to day basis, sediment deposition is in the conservation pool.
Over many years the sediment dropping out in the conservation pool will fill the pool forming more of a “dry reservoir” with a river running through it. The river will reach a point where the water velocity will keep suspended sediment from falling out according to the release rates from the dam. The preponderance of flood storage will still remain; however, there may no longer be a deep pool of water for recreational purposes.
c) What is the Corps doing to address these problems?
RESPONSE: We continue to perform periodic sedimentation surveys at our reservoirs and assess flood-storage capacity issues.
d) Can the capacity of the Coralville reservoir dam be increased through de-silting or raising the level of the dam?
RESPONSE: As noted in 6 (b), above, the preponderance of flood-storage capacity still remains despite sedimentation build up.
The capacity of the reservoir can be increased by dredging or emptying the reservoir to remove material to return it to its original design standards; however, dredging and issues related to disposal prove to be extremely costly. Raising the height of the dam would likely not be physically possible from an engineering and topography perspective.
7. Were all the flood gauge sensors in good working order prior to June 2008 flooding? If not, how is the Corps addressing this problem?
RESPONSE: Yes. All river gages needed to run models to develop flood forecasts for the spring and summer 2008 were in working condition. If a gage is not functioning properly, the Corps and the USGS have a team of technicians that will inspect the gage in person and make any repairs needed.
8. Regarding the definition of the 100 year flood, how has the expected 100 year flow (at the Coralville Dam’s tailwaters) changed from the time the dam was constructed 50 years ago until today? Is there a trend in the data. That is, can we anticipate that the 100 year flood, as defined in 50 years will be greater than the current definition by about the same amount as the current definition is greater than that offered when the dam was built?
RESPONSE: The Corps plans to conduct an updated flow frequency analysis for the Iowa River from Coralville Reservoir downstream to the confluence with the Mississippi River which will include the 2008 flood event. Until the revised analysis has been completed, it will not be possible to examine trends in the data.
9. Does the Corps operate on the assumption that global warming is a present reality and one that will shape meteorological conditions in the coming decades? If so, how does the Corps incorporate long-term predictions of significantly more precipitation for the upper Midwest and increasingly unpredictable weather conditions into its models for operating the dam?
RESPONSE: There are many disparate views by climatologists regarding global warming. As global warming science and trends are developed and verified, the Corps will consider their implications when developing it projects and operating plans.
Whether or not global warming has an impact on current or future meteorological conditions, the Corps will continue to work closely with the National Weather Service and the U.S. Geological Survey to monitor ground conditions, snowmelt and flood potential and operate our reservoirs accordingly.
10. We had the impression last June that the reservoir release rates were being set largely on the basis of water already in the Iowa River basin, or even on the basis of water already in the reservoir, as many of the public pronouncements from the Corps were stated in terms of "if no more rain falls, this is what we expect." How much does the corps look at weather forecasts? The weather bureau's short term forecasts seem to give fairly reliable (on the scale of the Iowa River basin) estimates of expected rainfall a day or two in advance, and useful estimates up to about a week in advance.
RESPONSE: All National Weather Service river forecasts include runoff from rain that has fallen over the previous 24 hours and runoff from rain that is forecasted to occur over the next 24 hours. The statement, “If no more rain falls,” meant that if no more rain falls above and beyond what is predicted by the NWS over the next 24-hour period.
During flood control operations, weather parameters are evaluated on an hourly basis to consider rainfall in the drainage area above the reservoirs; rainfall below the reservoirs; and National Weather Service rainfall predictions over a 24-hour period. This information is used by the Corps to anticipate inflows to the reservoirs and make adjustments to release rates to conserve flood storage capacity and minimize both up-river and down-river flooding.
11. How do cities rank among the Corps' priorities for flood protection?
RESPONSE: Reducing flood risk to property and the public is the primary purpose of all of our flood risk management projects. We take that responsibility very seriously and have constructed more than 100 projects within our 78,000-square-mile area of operations. Since their construction, these projects have cumulatively prevented more than $8.4 billion in property damages.
Coralville Reservoir was constructed at a time when there was little development in the floodplain. As cities and towns grow, so does development in the floodplain. This continued development places additional constraints on the operation of the reservoir and the current regulation manual attempts to take this growth into consideration for all properties below the reservoir, not Iowa City alone.
Coralville Reservoir was constructed at a cost of approximately $15,750,000, in 1958. Since then, the reservoir has prevented an estimated $167.5 million in property damages.
In 2008, the reservoir successfully reduced flows on the Iowa River below the dam by 17,500 cubic feet per second, which reduced the River’s flood stage by 5.0 feet. An estimated $99 million in damages were prevented due to the river stage reduction in Iowa City and downstream.
The three reservoirs (Saylorville, Red Rock and Coralville) built and maintained by the U.S. Army Corps of Engineers, Rock Island District, are operated as multi-purpose dams. The primary purpose authorized by Congress is for flood damage reduction for public and private property below the reservoirs. Other purposes include recreation and conservation. Corps reservoirs also maintain a conservation summer pool to augment low flows during drought and an additional fall pool raise to provide habitat for migrating bird species.
12. What can the City (and other entities in the Iowa City metro area) change to allow the Corps to release more water at the beginning of the spring flood season when the river is at a lower level?
RESPONSE: City officials could make a request to the state to have the reservoir’s operations manual reviewed for possible revision. To modify outflows on a permanent basis would require a revision of the Coralville Reservoir operations manual. Revising the manual requires a request from the state of Iowa and a cost-sharing of 50 percent of the study. The Corps would also require appropriations from Congress for our cost share of the study. The cost of the study would have to be determined once the scope of the study was developed.
13. Farmland downriver from Iowa City:
a) How much farmland south of Iowa City is in danger of flooding after May 1st of each year?
RESPONSE: All public and personal property below Coralville Reservoir is at risk of flooding. Flooding can occur at any time due to excessive snowmelt and rainfall in the spring, and excessive rainfall in the summer.
b) Would buying up farmland downriver to create a larger flood plain reduce risk of flooding in Iowa City?
RESPONSE: The purchase of agricultural land downstream would allow for higher reservoir releases. However, higher release rates at the reservoir would also create flooding in Iowa City.
To determine if additional farmland could be purchased and flooded, and what impact it would have on Iowa City, would require a cost-shared study with the Corps receiving appropriations from Congress for our share of the study. The cost of the study would have to be determined once the scope of the study was developed.
Additionally, an authorization and appropriation from Congress for the Corps to purchase farm land below the reservoir would be required.
c) Would it be legally possible to buy up this farmland?
RESPONSE: While it is legally possible to purchase farmland above and below Coralville Reservoir from willing sellers, the Corps does not have the authority, or the funding to do so.
d) Would it cost less to buy this farmland than other mitigation options in Iowa City?
RESPONSE: To determine if the cost of purchasing farmland is greater or less than the cost of other mitigation options in Iowa City, would, again, require a cost-shared study to review all available alternatives and their associated costs. The Corps would need to receive appropriations from Congress for our share of the study. The cost of the study would have to be determined once the scope of the study was developed.
Additionally, an authorization and appropriation from Congress for the Corps to purchase farm land below the reservoir would be required.
14. What are the costs and benefits to the Park View Terrace Neighborhood of Coralville building their proposed flood wall?
RESPONSE: This question would be best answered by Iowa City officials as it is not within the purview of the Corps of Engineers.
15. What impact would raising Dubuque Street have on Park View Terrace?
RESPONSE: This question would be best answered by Iowa City officials as it is not within the purview of the Corps of Engineers.
16. If the University of Iowa builds walls on both sides of river from the Park Road Bridge to the Burlington Street bridge (and the power plant south of it), what impact would they have on Park View Terrace? We understand that narrower channels invariably seem to have steeper gradients, while the gradient decreases when the river is allowed to spread. Again, we worry that Park View Terrace residents could become the victim of aggressive flood control measures elsewhere in the area.
RESPONSE: This question would also be best answered by Iowa City officials as it is not within the purview of the Corps of Engineers. The Iowa Department of Natural Resources Flood Plain Development Program department would also be a more appropriate agency to contact regarding this question.
Questions pertaining to the Flood of 2008
17. What impact did the Park Road Bridge have on flooding in Park View Terrace? What impact would redesigning the Park Road Bridge have on our neighborhood?
RESPONSE: As above, this question should be addressed to Iowa City officials as it is not within the purview of the Corps of Engineers. The Iowa Department of Natural Resources Flood Plain Development Program department would also be a more appropriate agency to contact regarding this question.
18. The University of Iowa has a coffer dam across the Iowa River, north of the Burlington Bridge. This dam has been in place for two or more years.
a) What impact did this coffer dam have on flooding in Park View Terrace?
RESPONSE: Without detailed study, it would be difficult to determine the impacts of the coffer dam on flooding in Park View Terrace. At this time, the Corps has no knowledge or information to suggest the cofferdam had an impact on the flooding at Park View Terrace.
The city had a consulting firm perform backwater analyses to monitor the effects of the cofferdam at different flows. This question should be addressed to the city or the University as it would be more appropriate for them to respond.
b) When did the Corps become aware of the Coffer Dam?
RESPONSE: The Corps received an application to install two chilled water mains under the Iowa River from the University of Iowa and their agent, NNW, Inc., on August 18, 2006.
On August 21, 2006, the proposed utility project with associated cofferdam was routed for comments through the Corps’ Engineering and Operations offices and the Iowa Department of Natural Resources (IADNR). Our reviewed resulted in no concerns; the IADNR required a mussel survey.
Eventually, the site was cleared for state of Iowa threatened and endangered species and the Corps issued a nationwide permit verification letter on October 5, 2006. In our letter we notified the permittee that ". . . the contractor's progress may be impeded by high flows in the late winter, spring, and early summer months, and the Corps of Engineers does not adjust reservoir releases at Coralville Lake for contract work."
On January 28, 2008, NNW, Inc., requested an extension of time to complete the project under the new series of nationwide permits which were issued on March 19, 2007. The Corps verified that the project under construction met the conditions of the new nationwide permits, and a permit verification letter was issued on February 14, 2008.
The Iowa Department of Natural Resources issued Sovereign Lands Construction Permits on September 27, 2006 and September 05, 2008.
c) Who issues permits for Coffer Dams, and do you know if the University obtained such a permit?
RESPONSE: The U.S. Army Corps of Engineers issues permits for any construction in navigable waters or the discharge of dredged or fill material into waters of the United States. The Iowa River is classified as a navigable waterway from its mouth to mile 3.0 near Toolesboro, Iowa.
We have a joint application process in place where copies of the application are simultaneously sent to the Corps and the Iowa Department of Natural Resources for review. The DNR issues Section 401 Water Quality Certification, Sovereign Lands Construction Permits and Floodplain Construction Permits in coordination with the Corps but independently with their own process.
The Corps issued a nationwide permit verification letter on October 5, 2006, for the project. On January 28, 2008, NNW, Inc., requested an extension of time to complete the project under the new series of nationwide permits which were issued on March 19, 2007. The Corps verified that the project under construction met the conditions of the new nationwide permits, and a permit verification letter was issued on February 14, 2008.
The Iowa Department of Natural Resources issued Sovereign Lands Construction Permits on September 27, 2006 and September 05, 2008.
19. Some engineers have estimated that had the Corps released 18,000 cfs starting May 23rd or so then water may have not gone over the spillway in 2008. Is that correct?
RESPONSE: The Corps ran a simulation of the 2008 flood using an 18,000 cubic feet per second release rate beginning May 23. Results of that simulation indicate the reservoir level would have still exceeded the crest of the spillway and that an 18,000 cfs release could not have been maintained due to physical limitations with regard to outlet capacity.
20. FEMA informed Park View Terrace residents in July 2008 that they knew by March 2008 that there could be a flood this year. Did the Corps have similar knowledge?
RESPONSE: We are unable to comment on what statements a representative from FEMA might have said in March 2008.
The National Weather Service provides flood forecasting information. Our first notification of potential flooding on the Iowa River basin and throughout the Midwest was provided to us near the end of May 2008. At that time, we sent our flood area engineers into the field to advise local communities and municipalities of the flood potential and offer any Corps assistance available. The National Weather Service forecasts are available on the web @ www.nws.noaa.gov and at www.rivergages.com.
21. Did the Corps know how high the crest might be in IC earlier than June 11, 2008? If Yes, did the Corps advise the City?
RESPONSE: No, we did not. It was not possible to model and forecast the height of the crest until after the heavy rains in the basin the night of June 12.
Beginning in early June, Corps Water Management staff provided daily and sometimes more frequent briefings on reservoir releases and forecasts to city, county and university officials. At times, we delayed increasing releases from Coralville Reservoir to provide ample time for emergency responders to remove property from anticipated flood areas, sandbag city infrastructure and personal property, and to provide the public with the maximum amount of time possible to implement flood protection for their personal property or evacuate if needed.
The District responded during the 2008 flood by deploying nearly 300 employees throughout the Midwest to work closely with state and local emergency responders to inspect, advise and assist communities with professional engineering expertise and materials during flood fights.
In all, the Corps provided nearly 13 million sandbags, 100 pumps, and more than 30 miles of plastic to assist local communities and levee districts in their flood-fight effort.
We deployed Corps engineers to Iowa City, Des Moines, Cedar Rapids, the Quad Cities, and throughout the state of Iowa advising emergency officials of the National Weather Service flood forecasts and our operations of reservoirs.
22. Had the Corps been able to release 12,000 cfs in the spring of 2008 instead of the 10,000 permitted under current rules, how much would this have reduced the peak flood release on June 15? We note that, at 10,000 CFS, northbound Dubuque Street was only inches above water. The point of this question is to help us evaluate the importance of elevating northbound Dubuque Street, since we suspect that this would have allowed both increased drawdown prior to the flood.
RESPONSE: The Corps ran a simulation of the 2008 flood using a 12,000 cubic feet per second release rate instead of the current 10,000 cfs maximum release rate stipulated in the reservoir regulation plan. Results of that simulation indicate the maximum reservoir release during the flood would have only been 1,000 cfs lower.
Friday, January 09, 2009
1. What is the Corps of Engineers doing/going-to-do to minimize the chances of another flood in PVT in Spring 2009?
RESPONSE: Flooding in Park View Terrace will continue to be a possibility dependent on snowmelt and rainfall amounts within the 3,115 square-mile watershed flowing into Coralville Reservoir and below the Reservoir.
Coralville Reservoir will always reduce peak flows on the Iowa River below the reservoir, regardless of the size of a flood, which will minimize flooding in PVT, Iowa City and areas downstream of the reservoir. The highest outflow during any given event will always be less than the peak inflow, even when water is well over the top of the spillway. The dam stores water when its pool elevation is increasing, meaning that the inflow is greater than the outflow. A few days after the peak inflow has occurred, the pool elevation will crest when the inflow equals what is being released in the outflow.
In 2008, we coordinated releases from Coralville Reservoir with Iowa City officials to provide ample time for emergency responders to remove property from anticipated flood areas, sandbag city infrastructure and personal property, and to provide the public with the maximum amount of time possible to implement flood protection for their personal property or evacuate if needed. During the 2008 flood, Coralville Reservoir successfully reduced flows on the Iowa River below the dam by 17,500 cubic feet per second, which reduced the River’s flood stage by 5.0 feet.
Prior to, and during, the 2008 flood, the Corps deployed flood-area engineers to Iowa City, Des Moines, Cedar Rapids, the Quad Cities, and throughout the state of Iowa advising emergency officials of the National Weather Service flood forecasts and our operations of reservoirs.
We will implement all of these actions again in 2009 if needed.
In late winter and early spring, the Corps will again work closely with the National Weather Service and the U.S. Geological Survey to monitor ground conditions, snowmelt and flood potential. During that time, we will maintain the Reservoir according to its approved Regulation Manual.
In the spring, the reservoir pool levels are maintained to allow for snow melt runoff, and for predicted and actual rainfall, to prevent downstream flooding. The pool levels will occasionally fluctuate to prepare for such runoff and for National Weather Service rainfall predictions. Pool levels are also maintained to ensure minimal bank erosion which contributes to sedimentation on the reservoir floor, adequate summer water supply, continued river flow below the reservoir, conservation purposes, and for Iowa and surrounding areas recreational opportunities.
During flood control operations, weather parameters are evaluated on an hourly basis to consider rainfall in the drainage area above the reservoirs; rainfall below the reservoirs; and National Weather Service rainfall predictions over a 24-hour period. This information is used by the Corps to anticipate inflows to the reservoirs and make adjustments to release rates to conserve flood storage capacity and minimize both up-river and down-river flooding.
2. Instead of waiting until the level at the reservoir reaches 700 feet to get active about moving water out of it, why not move it out sooner, say, at about 680 feet? It seems like waiting that long is almost too late and if any unforeseen rain comes in from the north, there isn’t enough wiggle room. Is there a possibility of changing the outflow numbers?
RESPONSE: As you know, the Coralville Reservoir is operated according to its approved Regulation Manual. All of our reservoirs are operated to conform to a strict, standard regulation plan that is coordinated by the Corps of Engineers for review and approval by local, state and federal agencies with water resources responsibilities. This standard includes regulation of releases during flood events. The latest revision occurred in January 2001 and was subject to public review and comment. A copy of the manual is available on the CD-ROM provided at this meeting (Note: The manual on the CD-ROM does not include plates and diagrams of the reservoir for security purposes).
Outflow modifications during flood emergencies are considered at the request of public officials. If outflow modifications are warranted, approval from our higher headquarters is required. We do not modify outflows during normal operating conditions.
To modify outflows on a permanent basis would require a revision of Coralville Reservoir’s operations manual. Revising the manual requires a request from the state of Iowa and a cost-sharing of 50 percent of the study. The Corps would also require appropriations from Congress for our cost share of the study. The cost of the study would have to be determined once the scope of the study was developed.
3. What is the minimum level of water that must be retained in the Coralville reservoir for:
a) protection of wildlife,
b) move sewage downstream, and
c) for recreational boating?
RESPONSE: These issues were considered as well as others when the following lake levels were determined, but there is no specific level for each.
The current approved operating levels are essential in order to protect fisheries within the reservoir and provide a minimum 150 cubic feet per second outflow as required by the state to meet downstream water quality targets during droughts. The current approved operating pool levels are:
15 February – 20 March: 683 to 679 National Geodetic Vertical Datum (NGVD) *
20 March – 20 May Hold @ 679 NGVD *
20 May – 15 September Hold @ 683 NGVD
15 September – 15 December Hold 683 to 686 NGVD **
15 December – 15 February Hold @ 683 NGVD
Notes:
* Variable draw down based on snow cover, ice, and 30-day climatic conditions coordinated with IDNR
** Dates and elevation of fall pool raise coordinated with the IDNR
4. Communications and the Corps
a) How does the Corps coordinate communication in times of flooding? Does it give directives for local councils regarding mandatory evacuation and other actions, or does it leave all these decisions to each city and township? (Could this info be shown on a diagram or in a written document).
RESPONSE: During periods of predicted and actual flooding, the Corps dispatches flood-area engineers to communities that may be affected by, or are affected by, flooding to alert communities to the flood projections and to provide technical flood-fighting support. Our Emergency Operations Center at Rock Island, Illinois, is activated and we are in regular communication with officials from affected communities, State emergency operations staff, and the Department of Homeland Security.
In addition, Corps water management and reservoir staff conducted daily teleconferences each morning (and sometimes more frequently)with Iowa City, the University of Iowa, the city of Coralville, and the Iowa Department of Transportation to aid them in the their decision-making process with regard to flood fighting, evacuations and road closures. This process will be followed during all future floods.
The Corps can only advise officials of what might happen and provide our professional opinion of a flooding situation. We do not have the authority to require evacuations or any other mandatory actions from local officials.
b) Will the Corps be communicating with Iowa City in the future to advise us of high water and how it will impact Park View Terrace?
RESPONSE: As in the past, and during the 2008 flood, if flooding is a concern, the Corps will dispatch flood-area engineers to Iowa City to ensure communities are aware of flood impacts and to provide technical flood-fighting support as needed. The Corps will continue to advise city officials of what might happen and provide our professional opinion of a flood situation.
Due to lessons learned during the 1993 and subsequent floods, and improved technology, we believe we had much better communication with affected communities during the 2008 flood. This will only continue to improve with additional lessons learned and better technology.
c) We have found the Corps forecasts of flood levels at the hydraulics lab gauging station less than helpful. The problem is that the gauging station is in a choke-point in the river valley and it is immediately downstream of a dam, so a 4-foot rise there does not translate to a 4-foot rise in areas where the floodplain is wider and dams are distant (as in our neighborhood). Could the Corps offer river-level forecasts for developed areas along the river such as ours?
RESPONSE: The Corps does not forecast river levels for Iowa City as the National Weather Service (NWS) is the agency responsible for issuing all weather and river forecasts to the public. The Corps does provide a 7-day outflow forecast from Coralville Reservoir to the NWS. The NWS incorporates the outflow information along with flows on Rapid Creek and Clear Creek to develop a river forecast for Iowa City.
The stream gaging network in place today is a mix of gages funded by the Corps, the USGS and other cooperators. Each agency operates and maintains their gages as resources allow. Together, the network provides the necessary data for the NWS to model stream and river conditions to provide the best-available river level forecasts. These forecasts are available on the internet @ http://www.nws.noaa.gov/ and at www.rivergages.com.
While additional gaging stations along rivers and tributaries are always useful, the Corps is not funded at this time to install and maintain additional gauges. However, it should be noted that the USGS gage at the hydraulics lab has a long period of record and is an excellent location with regard to maintaining a stable stage versus flow relationship which is essential to providing an accurate forecast. In lieu of installation of an additional gage, Park View residents can relate actual flooding that has occurred on their property historically to Iowa City gage readings.
5. Do Corps personnel ever come "in person" checking rivers downstream of Coralville Reservoir? Because it was clear for us riverside residents that river was very high since March 2008, and then, once or twice, it went down almost eerie low in April, then the flood came. Something was amiss, something that the computers probably got wrong, but human eyes could easily recognize.
RESPONSE: The low river levels that were observed in April were due to a temporary outflow reduction required to reduce flooding downstream at Wapello and Burlington and not a gage malfunction. If a gage is not functioning properly, the Corps and USGS deploy technicians that will inspect the gage in person and make any repairs needed.
The Corps of Engineers relies on our system of gages to operate all of our reservoirs, including the Coralville Reservoir. Gage data is provided via satellite to provide real-time flow information which allows us to operate our reservoirs to the best of our abilities.
6. Since Hurricane Katrina levee collapse and the Minneapolis I35 bridge collapse, we are hearing a lot about many US infrastructure failures -- out of date facilities, poor maintenance, and recurring human errors. Therefore,
a) What, frankly, is the state of the Coralville Dam currently?
RESPONSE: The U.S. Army Corps of Engineer’s dams are managed through the Dam Safety Program, which includes routine inspections and continual evaluations in accordance with the Federal Guidelines for Dam Safety issued in 1979 and 2004. The primary objective of the Dam Safety Program is to improve public safety by ensuring that Corps-owned and operated dams are structurally sound and operated according to the intended purpose; and that risks to the public are minimized.
There are no structural or other operating concerns at Coralville Reservoir. The Reservoir received a thorough inspection in August 2008 following the flood. Prior to that in August 2006, the Screening Risk Portfolio Analysis team that assesses dam safety rated Coralville Dam as being in good overall condition.
Corps dams are designed to withstand enormous pressures and water levels. All Corps reservoirs are built to stringent engineering standards to ensure they will withstand record flood events. Each reservoir is under observation to ensure its structural integrity and safety.
Reservoirs are also visually inspected on a regular basis under normal operating conditions and are visually inspected several times a day during flood events. Minor erosion adjacent to the outlet works can occur during major flood events but does not impair the structural integrity of the dam. The dam was thoroughly inspected after 1993 and 2008 and no movement or deterioration has been noted.
b) What is the REAL lifetime of the reservoir (we've heard everything from 50 years to 100 years)? What are the factors for determining the reservoir's lifetime, how does silting-in factor? What capacity has been lost due to silting-in and how does that relate to water upstream and the altered retention capability of the reservoir.
RESPONSE: Any sedimentation below the conservation pool does not impact flood storage. As an example, take two cups of equal size. One cup is half full of water and the other cup is half full of saturated silt, both cups still have the same amount of water storage volume left in them.
Sedimentation impacts are mostly recreational and environmental within the conservation pool. While the deposition of sediment continues to occur, the majority of sediment deposition has been in the conservation pool. For example, Coralville reservoir still retains approximately 89% of its original flood storage capacity, in comparison to only 55 percent of its original conservation storage capacity. Major flood events deposit sediment in the flood control pool, but on a day to day basis, sediment deposition is in the conservation pool.
Over many years the sediment dropping out in the conservation pool will fill the pool forming more of a “dry reservoir” with a river running through it. The river will reach a point where the water velocity will keep suspended sediment from falling out according to the release rates from the dam. The preponderance of flood storage will still remain; however, there may no longer be a deep pool of water for recreational purposes.
c) What is the Corps doing to address these problems?
RESPONSE: We continue to perform periodic sedimentation surveys at our reservoirs and assess flood-storage capacity issues.
d) Can the capacity of the Coralville reservoir dam be increased through de-silting or raising the level of the dam?
RESPONSE: As noted in 6 (b), above, the preponderance of flood-storage capacity still remains despite sedimentation build up.
The capacity of the reservoir can be increased by dredging or emptying the reservoir to remove material to return it to its original design standards; however, dredging and issues related to disposal prove to be extremely costly. Raising the height of the dam would likely not be physically possible from an engineering and topography perspective.
7. Were all the flood gauge sensors in good working order prior to June 2008 flooding? If not, how is the Corps addressing this problem?
RESPONSE: Yes. All river gages needed to run models to develop flood forecasts for the spring and summer 2008 were in working condition. If a gage is not functioning properly, the Corps and the USGS have a team of technicians that will inspect the gage in person and make any repairs needed.
8. Regarding the definition of the 100 year flood, how has the expected 100 year flow (at the Coralville Dam’s tailwaters) changed from the time the dam was constructed 50 years ago until today? Is there a trend in the data. That is, can we anticipate that the 100 year flood, as defined in 50 years will be greater than the current definition by about the same amount as the current definition is greater than that offered when the dam was built?
RESPONSE: The Corps plans to conduct an updated flow frequency analysis for the Iowa River from Coralville Reservoir downstream to the confluence with the Mississippi River which will include the 2008 flood event. Until the revised analysis has been completed, it will not be possible to examine trends in the data.
9. Does the Corps operate on the assumption that global warming is a present reality and one that will shape meteorological conditions in the coming decades? If so, how does the Corps incorporate long-term predictions of significantly more precipitation for the upper Midwest and increasingly unpredictable weather conditions into its models for operating the dam?
RESPONSE: There are many disparate views by climatologists regarding global warming. As global warming science and trends are developed and verified, the Corps will consider their implications when developing it projects and operating plans.
Whether or not global warming has an impact on current or future meteorological conditions, the Corps will continue to work closely with the National Weather Service and the U.S. Geological Survey to monitor ground conditions, snowmelt and flood potential and operate our reservoirs accordingly.
10. We had the impression last June that the reservoir release rates were being set largely on the basis of water already in the Iowa River basin, or even on the basis of water already in the reservoir, as many of the public pronouncements from the Corps were stated in terms of "if no more rain falls, this is what we expect." How much does the corps look at weather forecasts? The weather bureau's short term forecasts seem to give fairly reliable (on the scale of the Iowa River basin) estimates of expected rainfall a day or two in advance, and useful estimates up to about a week in advance.
RESPONSE: All National Weather Service river forecasts include runoff from rain that has fallen over the previous 24 hours and runoff from rain that is forecasted to occur over the next 24 hours. The statement, “If no more rain falls,” meant that if no more rain falls above and beyond what is predicted by the NWS over the next 24-hour period.
During flood control operations, weather parameters are evaluated on an hourly basis to consider rainfall in the drainage area above the reservoirs; rainfall below the reservoirs; and National Weather Service rainfall predictions over a 24-hour period. This information is used by the Corps to anticipate inflows to the reservoirs and make adjustments to release rates to conserve flood storage capacity and minimize both up-river and down-river flooding.
11. How do cities rank among the Corps' priorities for flood protection?
RESPONSE: Reducing flood risk to property and the public is the primary purpose of all of our flood risk management projects. We take that responsibility very seriously and have constructed more than 100 projects within our 78,000-square-mile area of operations. Since their construction, these projects have cumulatively prevented more than $8.4 billion in property damages.
Coralville Reservoir was constructed at a time when there was little development in the floodplain. As cities and towns grow, so does development in the floodplain. This continued development places additional constraints on the operation of the reservoir and the current regulation manual attempts to take this growth into consideration for all properties below the reservoir, not Iowa City alone.
Coralville Reservoir was constructed at a cost of approximately $15,750,000, in 1958. Since then, the reservoir has prevented an estimated $167.5 million in property damages.
In 2008, the reservoir successfully reduced flows on the Iowa River below the dam by 17,500 cubic feet per second, which reduced the River’s flood stage by 5.0 feet. An estimated $99 million in damages were prevented due to the river stage reduction in Iowa City and downstream.
The three reservoirs (Saylorville, Red Rock and Coralville) built and maintained by the U.S. Army Corps of Engineers, Rock Island District, are operated as multi-purpose dams. The primary purpose authorized by Congress is for flood damage reduction for public and private property below the reservoirs. Other purposes include recreation and conservation. Corps reservoirs also maintain a conservation summer pool to augment low flows during drought and an additional fall pool raise to provide habitat for migrating bird species.
12. What can the City (and other entities in the Iowa City metro area) change to allow the Corps to release more water at the beginning of the spring flood season when the river is at a lower level?
RESPONSE: City officials could make a request to the state to have the reservoir’s operations manual reviewed for possible revision. To modify outflows on a permanent basis would require a revision of the Coralville Reservoir operations manual. Revising the manual requires a request from the state of Iowa and a cost-sharing of 50 percent of the study. The Corps would also require appropriations from Congress for our cost share of the study. The cost of the study would have to be determined once the scope of the study was developed.
13. Farmland downriver from Iowa City:
a) How much farmland south of Iowa City is in danger of flooding after May 1st of each year?
RESPONSE: All public and personal property below Coralville Reservoir is at risk of flooding. Flooding can occur at any time due to excessive snowmelt and rainfall in the spring, and excessive rainfall in the summer.
b) Would buying up farmland downriver to create a larger flood plain reduce risk of flooding in Iowa City?
RESPONSE: The purchase of agricultural land downstream would allow for higher reservoir releases. However, higher release rates at the reservoir would also create flooding in Iowa City.
To determine if additional farmland could be purchased and flooded, and what impact it would have on Iowa City, would require a cost-shared study with the Corps receiving appropriations from Congress for our share of the study. The cost of the study would have to be determined once the scope of the study was developed.
Additionally, an authorization and appropriation from Congress for the Corps to purchase farm land below the reservoir would be required.
c) Would it be legally possible to buy up this farmland?
RESPONSE: While it is legally possible to purchase farmland above and below Coralville Reservoir from willing sellers, the Corps does not have the authority, or the funding to do so.
d) Would it cost less to buy this farmland than other mitigation options in Iowa City?
RESPONSE: To determine if the cost of purchasing farmland is greater or less than the cost of other mitigation options in Iowa City, would, again, require a cost-shared study to review all available alternatives and their associated costs. The Corps would need to receive appropriations from Congress for our share of the study. The cost of the study would have to be determined once the scope of the study was developed.
Additionally, an authorization and appropriation from Congress for the Corps to purchase farm land below the reservoir would be required.
14. What are the costs and benefits to the Park View Terrace Neighborhood of Coralville building their proposed flood wall?
RESPONSE: This question would be best answered by Iowa City officials as it is not within the purview of the Corps of Engineers.
15. What impact would raising Dubuque Street have on Park View Terrace?
RESPONSE: This question would be best answered by Iowa City officials as it is not within the purview of the Corps of Engineers.
16. If the University of Iowa builds walls on both sides of river from the Park Road Bridge to the Burlington Street bridge (and the power plant south of it), what impact would they have on Park View Terrace? We understand that narrower channels invariably seem to have steeper gradients, while the gradient decreases when the river is allowed to spread. Again, we worry that Park View Terrace residents could become the victim of aggressive flood control measures elsewhere in the area.
RESPONSE: This question would also be best answered by Iowa City officials as it is not within the purview of the Corps of Engineers. The Iowa Department of Natural Resources Flood Plain Development Program department would also be a more appropriate agency to contact regarding this question.
Questions pertaining to the Flood of 2008
17. What impact did the Park Road Bridge have on flooding in Park View Terrace? What impact would redesigning the Park Road Bridge have on our neighborhood?
RESPONSE: As above, this question should be addressed to Iowa City officials as it is not within the purview of the Corps of Engineers. The Iowa Department of Natural Resources Flood Plain Development Program department would also be a more appropriate agency to contact regarding this question.
18. The University of Iowa has a coffer dam across the Iowa River, north of the Burlington Bridge. This dam has been in place for two or more years.
a) What impact did this coffer dam have on flooding in Park View Terrace?
RESPONSE: Without detailed study, it would be difficult to determine the impacts of the coffer dam on flooding in Park View Terrace. At this time, the Corps has no knowledge or information to suggest the cofferdam had an impact on the flooding at Park View Terrace.
The city had a consulting firm perform backwater analyses to monitor the effects of the cofferdam at different flows. This question should be addressed to the city or the University as it would be more appropriate for them to respond.
b) When did the Corps become aware of the Coffer Dam?
RESPONSE: The Corps received an application to install two chilled water mains under the Iowa River from the University of Iowa and their agent, NNW, Inc., on August 18, 2006.
On August 21, 2006, the proposed utility project with associated cofferdam was routed for comments through the Corps’ Engineering and Operations offices and the Iowa Department of Natural Resources (IADNR). Our reviewed resulted in no concerns; the IADNR required a mussel survey.
Eventually, the site was cleared for state of Iowa threatened and endangered species and the Corps issued a nationwide permit verification letter on October 5, 2006. In our letter we notified the permittee that ". . . the contractor's progress may be impeded by high flows in the late winter, spring, and early summer months, and the Corps of Engineers does not adjust reservoir releases at Coralville Lake for contract work."
On January 28, 2008, NNW, Inc., requested an extension of time to complete the project under the new series of nationwide permits which were issued on March 19, 2007. The Corps verified that the project under construction met the conditions of the new nationwide permits, and a permit verification letter was issued on February 14, 2008.
The Iowa Department of Natural Resources issued Sovereign Lands Construction Permits on September 27, 2006 and September 05, 2008.
c) Who issues permits for Coffer Dams, and do you know if the University obtained such a permit?
RESPONSE: The U.S. Army Corps of Engineers issues permits for any construction in navigable waters or the discharge of dredged or fill material into waters of the United States. The Iowa River is classified as a navigable waterway from its mouth to mile 3.0 near Toolesboro, Iowa.
We have a joint application process in place where copies of the application are simultaneously sent to the Corps and the Iowa Department of Natural Resources for review. The DNR issues Section 401 Water Quality Certification, Sovereign Lands Construction Permits and Floodplain Construction Permits in coordination with the Corps but independently with their own process.
The Corps issued a nationwide permit verification letter on October 5, 2006, for the project. On January 28, 2008, NNW, Inc., requested an extension of time to complete the project under the new series of nationwide permits which were issued on March 19, 2007. The Corps verified that the project under construction met the conditions of the new nationwide permits, and a permit verification letter was issued on February 14, 2008.
The Iowa Department of Natural Resources issued Sovereign Lands Construction Permits on September 27, 2006 and September 05, 2008.
19. Some engineers have estimated that had the Corps released 18,000 cfs starting May 23rd or so then water may have not gone over the spillway in 2008. Is that correct?
RESPONSE: The Corps ran a simulation of the 2008 flood using an 18,000 cubic feet per second release rate beginning May 23. Results of that simulation indicate the reservoir level would have still exceeded the crest of the spillway and that an 18,000 cfs release could not have been maintained due to physical limitations with regard to outlet capacity.
20. FEMA informed Park View Terrace residents in July 2008 that they knew by March 2008 that there could be a flood this year. Did the Corps have similar knowledge?
RESPONSE: We are unable to comment on what statements a representative from FEMA might have said in March 2008.
The National Weather Service provides flood forecasting information. Our first notification of potential flooding on the Iowa River basin and throughout the Midwest was provided to us near the end of May 2008. At that time, we sent our flood area engineers into the field to advise local communities and municipalities of the flood potential and offer any Corps assistance available. The National Weather Service forecasts are available on the web @ www.nws.noaa.gov and at www.rivergages.com.
21. Did the Corps know how high the crest might be in IC earlier than June 11, 2008? If Yes, did the Corps advise the City?
RESPONSE: No, we did not. It was not possible to model and forecast the height of the crest until after the heavy rains in the basin the night of June 12.
Beginning in early June, Corps Water Management staff provided daily and sometimes more frequent briefings on reservoir releases and forecasts to city, county and university officials. At times, we delayed increasing releases from Coralville Reservoir to provide ample time for emergency responders to remove property from anticipated flood areas, sandbag city infrastructure and personal property, and to provide the public with the maximum amount of time possible to implement flood protection for their personal property or evacuate if needed.
The District responded during the 2008 flood by deploying nearly 300 employees throughout the Midwest to work closely with state and local emergency responders to inspect, advise and assist communities with professional engineering expertise and materials during flood fights.
In all, the Corps provided nearly 13 million sandbags, 100 pumps, and more than 30 miles of plastic to assist local communities and levee districts in their flood-fight effort.
We deployed Corps engineers to Iowa City, Des Moines, Cedar Rapids, the Quad Cities, and throughout the state of Iowa advising emergency officials of the National Weather Service flood forecasts and our operations of reservoirs.
22. Had the Corps been able to release 12,000 cfs in the spring of 2008 instead of the 10,000 permitted under current rules, how much would this have reduced the peak flood release on June 15? We note that, at 10,000 CFS, northbound Dubuque Street was only inches above water. The point of this question is to help us evaluate the importance of elevating northbound Dubuque Street, since we suspect that this would have allowed both increased drawdown prior to the flood.
RESPONSE: The Corps ran a simulation of the 2008 flood using a 12,000 cubic feet per second release rate instead of the current 10,000 cfs maximum release rate stipulated in the reservoir regulation plan. Results of that simulation indicate the maximum reservoir release during the flood would have only been 1,000 cfs lower.
Green Shirt Announcement
Double click on image to view larger image.
Above is a copy of the flyer which gives the details for the work of the "Green Shirts" (Christian Reformed World Relief Committee Disaster Response Services) in Johnson County from Jan. 12 to Jan. 17. The purpose of their visit is to try and document all the unmet needs that exist in the county since the June flood. The development of this information is critical to the Long Term Recovery Committee, which is embarking on fund raising efforts to help meet those needs during 2009 and the years beyond. It is essential that every flood victim be interviewed by the CRWRC volunteers so that we have a complete picture of what needs to be done in each individual case. This information will be put into a database and given to the LTRC for its use.
Please make sure the flyer appears on the website of your neighborhood, and please pass the word that the needs assessments are taking place next Monday thru Saturday. Also note that the first 200 persons to be interviewed will receive a $25 Hy-Vee gift card for participating.
Tuesday, January 6, 2009
Questions for the Corps to be Answered at the Jan. 10th Meeting
1. What is the Corps of Engineers doing/going-to-do to minimize the chances of another flood in PVT in Spring 2009?
2. Instead of waiting until the level at the reservoir reaches 700 feet to get active about moving water out of it, why not move it out sooner, say, at about 680 feet? It seems like waiting that long is almost too late and if any unforeseen rain comes in from the north, there isn’t enough wiggle room. Is there a possibility of changing the outflow numbers?
3. What is the minimum level of water that must be retained in the Coralville reservoir for:
a) protection of wildlife,
b) move sewage downstream, and
c) for recreational boating?
4. Communications and the Corps
a) How does the Corps coordinate communication in times of flooding? Does it give directives for local councils regarding mandatory evacuation and other actions, or does it leave all these decisions to each city and township? (Could this info be shown on a diagram or in a written document).
b) Will the Corps be communicating with Iowa City in the future to advise us of high water and how it will impact Park View Terrace?
c) We have found the Corps forecasts of flood levels at the hydraulics lab gauging station less than helpful. The problem is that the gauging station is in a choke-point in the river valley and it is immediately downstream of a dam, so a 4-foot rise there does not translate to a 4-foot rise in areas where the floodplain is wider and dams are distant (as in our neighborhood). Could the Corps offer river-level forecasts for developed areas along the river such as ours?
5. Do Corps personnel ever come "in person" checking rivers downstream of Coralville Reservoir? Because it was clear for us riverside residents that river was very high since March 2008, and then, once or twice, it went down almost eerie low in April, then the flood came. Something was amiss, something that the computers probably got wrong, but human eyes could easily recognize.
6. Since Hurricane Katrina levee collapse and the Minneapolis I35 bridge collapse, we are hearing a lot about many US infrastructure failures -- out of date facilities, poor maintenance, and recurring human errors. Therefore,
a) What, frankly, is the state of the Coralville Dam currently?
b) What is the REAL lifetime of the reservoir (we've heard everything from 50 years to 100 years)? What are the factors for determining the reservoir's lifetime, how does silting-in factor? What capacity has been lost due to silting-in and how does that relate to water upstreamand the altered retention capability of the reservoir.
c) What is the Corps doing to address these problems
d) Can the capacity of the Coralville reservoir dam be increased through de-silting or raising the level of the dam?
7. Were all the flood gauge sensors in good working order prior to June 2008 flooding? If not, how is the Corps addressing this problem?
8 . Regarding the definition of the 100 year flood, how has the expected 100 year flow (at the Coralville Dam’s tailwaters) changed from the time the dam was constructed 50 years ago until today? Is there a trend in the data. That is, can we anticipate that the 100 year flood, as defined in 50 years will be greater than the current definition by about the same amount as the current definition is greater than that offered when the dam was built?
9. Does the Corps operate on the assumption that global warming is a present reality and one that will shape meteorological conditions in the coming decades? If so, how does the Corps incorporate long-term predictions of significantly more precipitation for the upper Midwest and increasingly unpredictable weather conditions into its models for operating the dam?
10. We had the impression last June that the reservoir release rates were being set largely on the basis of water already in the Iowa River basin, or even on the basis of water already in the reservoir, as many of the public pronouncements from the Corps were stated in terms of "if no more rain falls, this is what we expect." How much does the corps look at weather forecasts? The weather bureau's short term forecasts seem to give fairly reliable (on the scale of the Iowa River basin) estimates of expected rainfall a day or two in advance, and useful estimates up to about a week in advance.
11. How do cities rank among the Corps' priorities for flood protection?
12. What can the City (and other entities in the Iowa City metro area) change to allow the Corps to release more water at the beginning of the spring flood season when the river is at a lower level?
13. Farmland downriver from Iowa City:
a) How much farmland south of Iowa City is in danger of flooding after May 1st of each year?
b) Would buying up farm land downriver to create a larger flood plain reduce risk of flooding in Iowa City?
c) Would it be legally possible to buy up this farmland?
d) Would it cost less to buy this farmland than other mitigation options in Iowa City?
14. What are the costs and benefits to the Park View Terrace Neighborhood of Coralville building their proposed flood wall?
15. What impact would raising Dubuque Street have on Park View Terrace?
16. If the University of Iowa builds walls on both sides of river from the Park Road Bridge to the Burlington Street bridge (and the power plant south of it), what impact would they have on Park View Terrace? We understand that narrower channels invariably seem to have steeper gradients, while the gradient decreases when the river is allowed to spread. Again, we worry that Park View Terrace residents could become the victim of aggressive flood control measures elsewhere in the area.
Questions pertaining to the Flood of 2008
17. What impact did the Park Road Bridge have on flooding in Park View Terrace? What impact would redesigning the Park Road Bridge have on our neighborhood?
18. The University of Iowa has a coffer dam across the Iowa river, north of the Burlington Bridge. This dam has been in place for two or more years.
a) What impact did this coffer dam have on flooding in Park View Terrace?
b) When did the Corps become aware of the Coffer Dam?
c) Who issues permits for Coffer Dams, and do you know if the University obtained such a permit?
19. Some engineers have estimated that had the Corps released 18,000 cfs starting May 23rd or so then water may have not gone over the spillway in 2008. Is that correct?
20. FEMA informed Park View Terrace residents in July 2008 that they knew by March 2008 that there could be a flood this year. Did the Corps have similar knowledge?
21. Did the Corps know how high the crest might be in IC earlier than June 11, 2008? If Yes, did the Corps advise the City?
22. Had the Corps been able to release 12,000 cfs in the spring of 2008 instead of the 10,000 permitted under current rules, how much would this have reduced the peak flood release on June 15? We note that, at 10,000 CFS, northbound Dubuque Street was only inches above water. The point of this question is to help us evaluate the importance of elevating northbound Dubuque Street, since we suspect that this would have allowed both increased drawdown prior to the flood.
2. Instead of waiting until the level at the reservoir reaches 700 feet to get active about moving water out of it, why not move it out sooner, say, at about 680 feet? It seems like waiting that long is almost too late and if any unforeseen rain comes in from the north, there isn’t enough wiggle room. Is there a possibility of changing the outflow numbers?
3. What is the minimum level of water that must be retained in the Coralville reservoir for:
a) protection of wildlife,
b) move sewage downstream, and
c) for recreational boating?
4. Communications and the Corps
a) How does the Corps coordinate communication in times of flooding? Does it give directives for local councils regarding mandatory evacuation and other actions, or does it leave all these decisions to each city and township? (Could this info be shown on a diagram or in a written document).
b) Will the Corps be communicating with Iowa City in the future to advise us of high water and how it will impact Park View Terrace?
c) We have found the Corps forecasts of flood levels at the hydraulics lab gauging station less than helpful. The problem is that the gauging station is in a choke-point in the river valley and it is immediately downstream of a dam, so a 4-foot rise there does not translate to a 4-foot rise in areas where the floodplain is wider and dams are distant (as in our neighborhood). Could the Corps offer river-level forecasts for developed areas along the river such as ours?
5. Do Corps personnel ever come "in person" checking rivers downstream of Coralville Reservoir? Because it was clear for us riverside residents that river was very high since March 2008, and then, once or twice, it went down almost eerie low in April, then the flood came. Something was amiss, something that the computers probably got wrong, but human eyes could easily recognize.
6. Since Hurricane Katrina levee collapse and the Minneapolis I35 bridge collapse, we are hearing a lot about many US infrastructure failures -- out of date facilities, poor maintenance, and recurring human errors. Therefore,
a) What, frankly, is the state of the Coralville Dam currently?
b) What is the REAL lifetime of the reservoir (we've heard everything from 50 years to 100 years)? What are the factors for determining the reservoir's lifetime, how does silting-in factor? What capacity has been lost due to silting-in and how does that relate to water upstreamand the altered retention capability of the reservoir.
c) What is the Corps doing to address these problems
d) Can the capacity of the Coralville reservoir dam be increased through de-silting or raising the level of the dam?
7. Were all the flood gauge sensors in good working order prior to June 2008 flooding? If not, how is the Corps addressing this problem?
8 . Regarding the definition of the 100 year flood, how has the expected 100 year flow (at the Coralville Dam’s tailwaters) changed from the time the dam was constructed 50 years ago until today? Is there a trend in the data. That is, can we anticipate that the 100 year flood, as defined in 50 years will be greater than the current definition by about the same amount as the current definition is greater than that offered when the dam was built?
9. Does the Corps operate on the assumption that global warming is a present reality and one that will shape meteorological conditions in the coming decades? If so, how does the Corps incorporate long-term predictions of significantly more precipitation for the upper Midwest and increasingly unpredictable weather conditions into its models for operating the dam?
10. We had the impression last June that the reservoir release rates were being set largely on the basis of water already in the Iowa River basin, or even on the basis of water already in the reservoir, as many of the public pronouncements from the Corps were stated in terms of "if no more rain falls, this is what we expect." How much does the corps look at weather forecasts? The weather bureau's short term forecasts seem to give fairly reliable (on the scale of the Iowa River basin) estimates of expected rainfall a day or two in advance, and useful estimates up to about a week in advance.
11. How do cities rank among the Corps' priorities for flood protection?
12. What can the City (and other entities in the Iowa City metro area) change to allow the Corps to release more water at the beginning of the spring flood season when the river is at a lower level?
13. Farmland downriver from Iowa City:
a) How much farmland south of Iowa City is in danger of flooding after May 1st of each year?
b) Would buying up farm land downriver to create a larger flood plain reduce risk of flooding in Iowa City?
c) Would it be legally possible to buy up this farmland?
d) Would it cost less to buy this farmland than other mitigation options in Iowa City?
14. What are the costs and benefits to the Park View Terrace Neighborhood of Coralville building their proposed flood wall?
15. What impact would raising Dubuque Street have on Park View Terrace?
16. If the University of Iowa builds walls on both sides of river from the Park Road Bridge to the Burlington Street bridge (and the power plant south of it), what impact would they have on Park View Terrace? We understand that narrower channels invariably seem to have steeper gradients, while the gradient decreases when the river is allowed to spread. Again, we worry that Park View Terrace residents could become the victim of aggressive flood control measures elsewhere in the area.
Questions pertaining to the Flood of 2008
17. What impact did the Park Road Bridge have on flooding in Park View Terrace? What impact would redesigning the Park Road Bridge have on our neighborhood?
18. The University of Iowa has a coffer dam across the Iowa river, north of the Burlington Bridge. This dam has been in place for two or more years.
a) What impact did this coffer dam have on flooding in Park View Terrace?
b) When did the Corps become aware of the Coffer Dam?
c) Who issues permits for Coffer Dams, and do you know if the University obtained such a permit?
19. Some engineers have estimated that had the Corps released 18,000 cfs starting May 23rd or so then water may have not gone over the spillway in 2008. Is that correct?
20. FEMA informed Park View Terrace residents in July 2008 that they knew by March 2008 that there could be a flood this year. Did the Corps have similar knowledge?
21. Did the Corps know how high the crest might be in IC earlier than June 11, 2008? If Yes, did the Corps advise the City?
22. Had the Corps been able to release 12,000 cfs in the spring of 2008 instead of the 10,000 permitted under current rules, how much would this have reduced the peak flood release on June 15? We note that, at 10,000 CFS, northbound Dubuque Street was only inches above water. The point of this question is to help us evaluate the importance of elevating northbound Dubuque Street, since we suspect that this would have allowed both increased drawdown prior to the flood.
Johnson County Long Term Recovery Committee
The Johnson County Long Term Recovery Committee invites property owners who sustained damage during last summer's flood to participate in a comprehensive assessment of unmet needs.
Trained and supervised volunteer teams from the Christian Reformed World Relief Committee (CRWRC) Disaster Response Services will be in Johnson County January 12-17. These "Green Shirts" will be conducting assessments at the Lobby Conference Room at Iowa City City Hall and at St. Andrew Presbyterian Church, 1300 Melrose Ave., next Monday, Tuesday, Friday, and Saturday 9:00 a.m.-4:00 p.m. and on Wednesday and Thursday, 9:00 a.m.-7:00 p.m.
Appointments are encouraged but not mandatory and may be made by calling United Way of Johnson County, 338-7823. The assessment takes about 30 minutes. The first 200 participants will receive a $25 Hy-Vee gift card. These reports will help us understand and work toward meeting the as-yet unmet needs and providing resources from various community organizations. If you are unable to come to either of these sites, arrangements can be made for volunteers to come to your current residence.
Contacts: Mark and Carol Martin Flood Recovery Coordinators for the CRC
Home: 319-354-1174
Mark's cell: 319-330-3030
Carol's cell: 319-330-5310
Trained and supervised volunteer teams from the Christian Reformed World Relief Committee (CRWRC) Disaster Response Services will be in Johnson County January 12-17. These "Green Shirts" will be conducting assessments at the Lobby Conference Room at Iowa City City Hall and at St. Andrew Presbyterian Church, 1300 Melrose Ave., next Monday, Tuesday, Friday, and Saturday 9:00 a.m.-4:00 p.m. and on Wednesday and Thursday, 9:00 a.m.-7:00 p.m.
Appointments are encouraged but not mandatory and may be made by calling United Way of Johnson County, 338-7823. The assessment takes about 30 minutes. The first 200 participants will receive a $25 Hy-Vee gift card. These reports will help us understand and work toward meeting the as-yet unmet needs and providing resources from various community organizations. If you are unable to come to either of these sites, arrangements can be made for volunteers to come to your current residence.
Contacts: Mark and Carol Martin Flood Recovery Coordinators for the CRC
Home: 319-354-1174
Mark's cell: 319-330-3030
Carol's cell: 319-330-5310
Sunday, January 4, 2009
Coralville Reservoir Release Rates
We had another terrific meeting. See slide show below. The bottom line is the Corps needs to make flood control the number 1 priority as they did in the 60's. They have raised the height of the reservoir by 13 feet since then - 670 verses 683. It needs to go back to 670 today! It's a plain and simple fact - 100 of millions of dollars of destruction have been caused by the misguided priorities of the Corps.
Uploaded on authorSTREAM by irwinre
Uploaded on authorSTREAM by irwinre
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