Year constructed: 1967
Bridge type: Prestressed Concrete Stringer/Beam/Girder
National Register of Historic Places status:
Eligible
Length: 563 feet
Width: 28 feet
Spans: 5
FHWA: 240385
Jurisdiction: Marion County
Location: Hwy T15 over the top of Red Rock Dam southwest of Pella, Section 19, T76N-R18W (Lake Prairie Township)
Details
Though seemingly a part of the dam structure, the concrete road over the spillway and dam was one of the last items constructed. In February 1966, the contract for the final earth embankment was let to William A. Smith Company of Kansas City, Kansas (Pella Chronicle February 1, 1966:1). By January 1968, work had begun on the roadway on top of the earth embankments; though the road over the spillway itself had already been completed (Pella Chronicle-Advertiser January 30, 1968:1).
The bridge was included in the Phase II survey as it is a large bridge of exceptional span or overall length, which according to the registration requirements in the MPD is a prestressed girder span (Type 502) with a span greater than 100’ or multiple span bridges with an overall length in excess of 400 feet. The bridge is 563' long with a main span of 113', which meets both the aforementioned registration requirements for prestressed concrete bridges. The bridge is also associated with the construction of the Red Rock Dam and Reservoir as it was built to span the spillway of the dam itself. As such, the Red Rock Dam Bridge is eligible for inclusion in the NRHP under Criteria A and C as it does meet the registration requirements outlined in the MPD .
Although, the bridge is less than 50 years of age, it does possess characteristics of exceptional importance and thus does meet Criteria Consideration G. The Red Rock dam and reservoir project was one of the largest undertakings of its kind in Iowa and the Red Rock Lake Bridge was the longest and tallest bridge in Iowa at the time of its construction.
The Red Rock Dam project was authorized in the Flood Control Acts of June 1938 and December 1944. In June 1944, the Senate Commerce Committee approved $15 million of the $1 billion national flood control program for a large dam to the southeast of Des Moines (Council Bluffs Nonpareil June 25, 1944:7). Floods in 1947 prompted a second dam on the Des Moines River at Saylorville (Pella Chronicle July 19, 1956:1). In 1956, planning for the project began. On June 4, 1960, the groundbreaking ceremony was held (Pella Chronicle June 9, 1960:1). Approximately 86 miles of railroad, 10 miles of state highway, 85 miles of county roads, and numerous bridges in the area would be impacted, either through submersion or relocation (Pella Chronicle-Advertiser September 3, 1969:9B). Thus, while the dam was being built, several new bridges and roads were constructed. The 5,653' Iowa 14 Bridge over the Des Moines River / Red Rock Lake (FHWA #35200) was designed by the Iowa Highway Commission and opened to traffic on November 4, 1965. The total cost of the bridge was $2,400,600. The concrete road over the spillway and dam (FHWA #240385) was one of the last items constructed in 1967 (Pella Chronicle-Advertiser January 30, 1968:1). The IA 316 Bridge (FHWA #280555) between Runnells and Swan was completed in 1968. New bridges also had to be built for relocated routes such as IA 5 southwest of Knoxville. On March 17, 1969, the dam went into operation and the permanent pool level of 725’ was reached in three days due to the spring melt (Pella Chronicle-Advertiser September 3, 1969:Special Insert, p.7). The Red Rock Dam and Reservoir was dedicated on September 6, 1969. Four days of festivities accompanied the dedication of the dam. When completed, the 6,300-acre dam was the largest man-made lake in Iowa.