Project OverviewProject Overview

The Red Rock Hydroelectric Project (RRHP) is licensed by the Federal Energy Regulatory Commission (FERC) and is located at the existing U.S. Army Corps of Engineers (USACE) Red Rock Dam on the Des Moines River, about 3.8 miles southwest of downtown Pella in Marion County, Iowa; approximately 45 miles southeast of Des Moines, Iowa; and approximately 143 miles above the confluence of the Des Moines River with the Mississippi River.

USACE constructed Red Rock Dam between 1960 and 1969 to impound Lake Red Rock for flood control, recreational, and fish and wildlife purposes. The dam, reservoir, and adjacent land are owned by the United States of America and operated by the Rock Island District of the USACE.

The RRHP facilities will be constructed immediately left (northeast) of the existing spillway largely within the envelopment section where the earthfill wraps around the end of the concrete dam. The approach channel and intake structure will be located upstream of the dam. Two penstocks will run from the intake structure through penetrations in the dam to the powerhouse located just left of the existing spillway tailrace. A tailrace channel will extend from the downstream end of the powerhouse to the existing spillway tailrace. Refer to Figure 1 and Figure 2 below for three-dimensional views of the Project features.


Figure 1: Upstream Features of the Red Rock Hydroelectric Project. 


Figure 2: Downstream Features of the Red Rock Hydroelectric Project.

Each penstock will supply water to a vertical Kaplan-type hydraulic turbine and each turbine will be directly connected to a generator. See Figure 3 below, which shows a typical vertical Kaplan turbine. 

Figure 3: Typical Vertical-Kaplan Turbine/Generator

Electricity from each generator will then be transferred through the plant to the plant substation, which will transform the electricity from 13,800 volts to 69,000 volts. From there, the electricity will flow through the transmission line to a substation located on the West side of Pella, Iowa, which connects to the regional transmission grid. The rated project generating capacity will be 36.4 MW at normal reservoir level (El. 742) and a combined flow rate of 8,900 cfs. The combined maximum generating capacity will be 55 MW at higher reservoir levels and/or flows. The estimated annual energy produced by the project will be 178,000 MWh, or enough to power approximately 18,000 homes.

RRHP will be operated in a “run-of-release” mode. This means that the USACE will determine how much water will be released from Lake Red Rock, just like they do today, and all, a portion, or none of the water will be directed through the hydroelectric facility depending on the amount of water that the USACE chooses to release.

Construction of RRHP will employ 150-200 workers at the peak of construction. Once online, the plant will create two permanent positions. 

For additional information about the dam or about RRHP, please email, or call us at (641) 620-1022.