Tour of Five Small Flood Control Dams in Iowa and Nebraska

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Tour of Five Small Flood Control Dams in Iowa and
Nebraska

• Rehabilitation Needs of Aging Small Flood Control
  Dams

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Over 11,000 small flood control dams have been
built in 2,000 watersheds in 47 states since 1948.
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These Dams Were Built by Local Sponsors Assisted
by the USDA Natural Resources Conservation
Service.

• Authorization for the construction of the dams
  came from
• Public Law 78-534 (Flood Control Act of 1944) and
• Public Law 83-566 (Watershed Protection and Flood
  Prevention Act of 1953).

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Earlier constructed dams were designed for a
50-year life span. A time that many dams are now
reaching. Over one-half of the dams are over 30
years old.
The question now is how can sponsors deal with
these aging dams that need major rehabilitation?
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Major Issues With Aging Dams

• Many of the dams have deteriorating concrete and
  metal components in the principal spillways and
  the lakes are filling with sediment. Some are
  unsafe.
• Some were designed for rural agricultural
  protection and now have homes, highways, and
  other structures downstream.
• Many sponsors dont have the funds and expertise
  to rehabilitate the dams.

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What This Tour Is About

• The following tour includes scenes and
  information about five small flood control dams
  in southwest Iowa and southeast Nebraska.
• These dams show some of the types of problems and
  issues that are facing local watershed sponsors
  across the nation

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Tour Map
The tour takes place south and east of Omaha,
Nebraska
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Hamburg Dam M1 Freemont Co., Iowa
Project Sponsors Fremont County Soil and Water
Conservation District City of Hamburg, Iowa
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Protecting Urban Areas
Hamburg Dam M1 was built in 1962 to control
erosion and to help control flooding in Hamburg,
Iowa.
Hamburg Dam No. M 1
Hamburg Dam M1
A school, homes, businesses and hospital are
immediately downstream from the dam. Loss of
lives is a possibility if the dam should fail.
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The dam is considered a high hazard structure
and was built under those standards.
Hamburg Dam M1
The original cost of the project in 1962 was
about 40,000. It would cost about 260,000 if
built today..
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This project is a good example of the kind
of protection and benefits provided by small
flood control dams. It also illustrates why
sponsors are looking at ways to extend the life
of the dams.
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Possible Courses of Action

• Decommission Upstream grade stabilization and
  original flooding problems would need to be
  addressed.
• Maintain the dam Continue to monitor the dam and
  components closely and analyze redesign or
  replacement of components in the future as
  necessary
• Remove/relocate downstream structures

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Pony Creek Dam No. 31 Mills County, Iowa
Project Sponsors Mills Co. Soil and Water
Conservation District Mills Co. Board of
Supervisors Pony Creek Drainage District No. 2
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Changing Conditions
Pony Creek Dam 31 is one of 24 dams built in the
Pony Creek Watershed in Mills County, Iowa to
stabilize gullies and reduce flooding.
Pony Creek Dam No. 31
The dam was built as a Class A (low hazard dam)
in 1963, but in 1974 U.S. Highway 34 was rerouted
to run just below the dam, which has changed the
hazard classification to a Class C (high hazard)
dam.
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Original cost of dam in 1963 was about 40,000.
Todays cost would be about 300,000
Pony Creek Dam No. 31
Pony Creek Dam No. 31
A deteriorating spillway pipe now puts the
highway in danger of being covered with 2 feet of
water if the dam should fail. Replacing the
spillway pipe and modifying the roadside to
redirect potential floodwaters would eliminate
this risk. About 8,000 people travel this section
of highway daily.
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Community Benefits
Pony Creek Dam No. 31
Pony Creek Dam No. 31

• The dam protects the Loess Hills from accelerated
  gully erosion and protects a highway and land
  below dam from flooding.
• It is a featured attraction in Mile Hill Park.
  The 13-acre lake provides opportunities for
  fishing and hiking.

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Possible Courses of Action

• Decommission Upstream grade stabilization would
  need to be addressed.
• Rebuild for Safety Major rebuilding of dam would
  need to address the disruption of park users, as
  well as possible damage to high quality woodland
  and fish habitat.
• Replace the spillway pipe Replacing the pipe and
  reshaping the road right of way will eliminate
  the concern for dam failure and can be done
  without major disruption to the site or damage to
  valuable archaeological sites in the area.

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Indian Creek Dam No. 2 Pottawattamie Co., Iowa
Project Sponsors West Pottawattamie Co. Soil
And Water Conservation District City of Council
Bluffs
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Protecting Urban Areas
Indian Creek Dam No. 2 is one of several dams
built just above the city of Council Bluffs,
Iowa. The 70-foot high dam was built in 1975 as a
grade stabilization, full flow structure on a
tributary of Indian Creek.
Indian Creek Dam No. 2
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Indian Creek Dam No. 2
Indian Creek Dam No. 2 dam is in good condition
now. The concern is that as the dam ages, a major
storm may result in failure of the dam and
massive damage downstream.
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Downstream from Dam
Failure of Indian Creek Dam No. 2 could
result in loss of lives and severe damages to
private and public facilities.
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Possible Courses of Action

• Decommission Upstream grade stabilization would
  need to be addressed to avoid return to original
  gully problems.
• Rebuild for Safety If breach studies show the
  hazard classification should be rated as high,
  redesign and rebuilding of spillway would be
  necessary.
• Remove/Relocate Existing Downstream Structures
  If breach studies show only limited structures
  are in danger, relocation of structures could be
  an option.

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Papillion Creek Dam No. 27
Sarpy County, Nebraska
Project Sponsor Papio-Missouri River Natural
Resources District
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From Rural to Urban
Papillion Creek Dam No. 27, Sarpy County,
Nebraska, is a good example of a dam that was
built on farmland and is now surrounded by homes.
Papillion Creek Dam No. 27
The dam was built in 1974 at a cost of 74,200
and would cost about 130,000 to build today.
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Papillion Creek Dam No. 2
This small grade stabilization structure also
serves as a sediment trap and has captured about
2.7 acre-feet of sediment.
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Papillion Creek Dam No. 2
The dam serves as a focal point for an
aesthetically pleasing urban neighborhood for
those building homes around it.
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Local homeowners use the area around the dam as a
walking trail and a place to view wildlife and
just enjoy the beauty around the small lake.
Papillion Creek Dam No. 2
So far no homes are below the dam. The upstream
hydrologic conditions have changed and will
change more as development continues. Major
concerns are corrosion of spillway conduit and
the increasing amount of sediment occurring.
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Possible Courses of Action

• Decommission Upstream grade stabilization would
  need to be addressed to avoid return to original
  gully problems.
• Rebuilt/modify for safety Widen the emergency
  spillway and remove sediment.
• Remove/relocate downstream structures There are
  currently no structures downstream, but future
  controls may be need to be placed on development.

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Brownell Creek Dam No. 13-6
Project Sponsor Nemaha Natural Resources District
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Deteriorating Metal and Concrete Components
Brownell Creek Dam No. 13-6 is located in Otoe
County, Nebraska. It was built as one of many
grade control structures on Otoe County farmland.
Brownell Creek Dam 13-6
The dam has stabilized gullies and provides
modest flood control benefits. There is no pool
of water, but it does provide wetland habitat.
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Brownell Creek Dam 13-6
This dam is an example of how metal and concrete
components are deteriorating and need
replacement. This structure has exceeded its
design life, but still serves its purpose of
controlling erosion and sediment.
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Possible Courses of Action

• Decommission Upstream grade stabilization would
  need to be addressed to avoid return to original
  gully problems.
• Replace/modify Replace the principal spillway,
  considering a rock chute and remove the sediment.
• Take no action This could result in dam failure
  in the future and lead to same results as
  decommissioning.

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National Rehabilitation Needs
An initial survey of states found 2,200 dams
need rehabilitating to keep them safe and
functioning as designed.
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Opportunities Exist

• Congress has passed legislation that authorizes
  cost share assistance for rehabilitation and for
  USDA technical assistance.
• Pilot rehabilitation projects are underway in
  five states.
• Information is being gathered to determine the
  needs and projected costs for rehabilitation.

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In 2001 over 400 Watershed Project Sponsors
Indicated an Interest in USDA Assistance in
Rehabilitating 1,434 Dams in 35 States.It Would
Cost Over 500 Million to Rehabilitate These Dams
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To Get More Information About Aging Flood Control
Dams and Rehabilitation Efforts

• Go to the USDA Natural Resources Conservation
  Service Web Page (www.nrcs.usda.gov)
• Click on to Aging Watersheds.