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Posted 4/27/2017

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Contact
Operations Project Manager
(515) 276-4656 x6504

Location
The Saylorville Lake Project, Johnston, IA, also includes the Big Creek Remedial Works which consists 3 dams, diversion channel, spillway and pump station. The Remedial Works protects Polk City, IA.

Description
The Big Creek Remedial Works Project was awarded the 1976 Chief of Engineers Distinguished Design Award.  Originally Polk City was to be protected with a system of tall levees, but placing dams both above and below the city eliminated the need for those levees. The Iowa Department of Natural Resources manages the ponding area behind the Barrier Dam as an inviolate refuge during a portion of the year to protect waterfowl.  The Big Creek Remedial Works provides protection for parts of Polk City Iowa and adjacent Big Creek Valley which are below the full flood pool level.  This flood protection system consists of:

  1. Barrier Dam: It protects Polk City from rising water in Saylorville Lake.
  2. Pump Station: Excess water can be drained into Saylorville Lake via gravity flow through a conduit in the Barrier Dam or pumped when Saylorville Lake levels rise. There are three 24” pumps with 350 h.p. motors which are each capable of pumping 17,000 gallons per minute when Saylorville Lake level is high with 50’ of water head pressure above the pumps.
  3. Diversion Dam: It formed 880 acre Big Creek Lake and protects Polk City from floodwaters within Big Creek Watershed. A minimum 3 cfs water quality release is maintained from the Diversion Dam through Polk City into the Ponding Area.
  4. Diversion Channel & Terminal Dam/Spillway: Diverts floodwater from Big Creek Lake into Saylorville Lake.  The spillway with a crest elevation of 920.0 NGVD keeps the lake level relatively stable at that elevation.

Due to land use changes in this 17 square mile watershed and changing weather patterns, increased flow frequency continues to occur.  During large magnitude flood events, this pumping station is unable to keep up with flows and additional auxiliary pumps are required to be installed.  During FY15-16, a design for a supplemental pump station was completed.  The supplemental pump station will contain (3) vertical turbine pumps and (3) 500 hp electric motors.  Each pump has a design capacity of 66,000 cfs each.  This supplemental pump station, when constructed, will operate in conjunction with the current pump station during large flood events.

Status
Project in Operation

Authority
OM - Operations and Maintenance

Summarized Project Costs

Estimated Federal Cost  $0 
Estimated Non-Federal Cost $0
Estimated Total Project Cost $0
Allocations Prior to Current FY 2017 Cost  $0
Current FY 2017 Allocation (received to date) $0
Current FY 2017 Total Capability  $0

Major Work Item Current Year
FY 2017: Project is in operation.