The Saylorville Lake Project, Johnston, Iowa, also includes the Big Creek Remedial Works.
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:
- Barrier Dam: It protects Polk City from rising water in Saylorville Lake.
- 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.
- Diversion Dam: It formed the 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.
- 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.
Project in operation.
OM – Operations and Maintenance
Flood Control Act of 1958
Summarized Project Costs
|Estimated Federal Cost
|Estimated Non-Federal Cost
|Estimated Total Project Cost
|Allocations Prior to FY 2020
|FY 2020 Allocation
|FY 2020 Total Capability
Major Work Item Current Year
FY 2020: Project is in operation.