The estimated costs to replace the Richmond Lake spillway now substantially exceed the $6.5 million set aside by the state in 2022.
That means more money is needed before work can begin.
The maintenance of the spillway falls under South Dakota School and Public Lands, the same agency that oversaw the recent replacement of the spillway on Elm Lake.
According to an update from School and Public Lands provided earlier this year to the Richmond Lake Homeowners Association, project estimates now range from $10.1 million to $26.8 million.
Deputy Commissioner Justin Nagel said the School and Public Lands office is exploring options that include seeking more money from the legislature next year and the potential of applying for a High Hazard Potential Dam federal grant.
Information about that federal grant program doesn’t indicate the maximum award possible, but about $11 million per year has been available in most recent years. However, in 2022, the grant pool was closer to $20 million.
Nagel said School and Public Lands is also seeking help from the South Dakota Office of Emergency Management to oversee the administration of the federal grant application. That office has more experience with federal grants, he said.
He said options for the spillway replacement include a similar structure with taller walls, a wider spillway with replacement of the bridge or replacement of the spillway with a weir structure. Each option includes erosion control, Nagel said.
A weir is a barrier built across a body of water to raise the water slightly on the upstream side.
Richmond, Elm and Mina spillways built in 1930s
The spillway at Richmond was built about the same time as the spillways that established Elm and Mina lakes.
All were constructed in the 1930s as Works Projects Administration jobs. The Elm and Mina spillways have been replaced in recent years. In each case, work started in late 2021 and was finished by spring 2022. They were done at a time when the water levels on the lakes were lower than usual, which meant plans to reduce the water in the lakes weren’t needed.
The new Elm spillway cost $5.77 million, and the work at Mina cost $4,15 million. The Mina job was overseen by the South Dakota Department of Game, Fish & Parks.
Mina’s dam was completed first in 1934, according to “Builders of Prairie Lakes,” a WPA publication on the three structures.
By the time the Mina’s spillway was finished for the purpose of creating Mina Lake and preserving Scatterwood Lake to the south, there was already talk about a spillway to establish Richmond Lake. Work on the Richmond structure began in September 1935, and park development started in 1937. Construction of the Elm Lake spillway began that same year.