Lac qui Parle Dam, Watson, Minnesota.
Purpose
The Lac qui Parle Emergency Spillway is designed to retain the Lac qui Parle Reservoir during normal conditions and overtop during flooding. The reference to “emergency” in the feature name is because its operation requires road closure. The overtop elevation of the spillway is 940.75 feet.
Location
The Lac qui Parle Dam is located on the upper Minnesota River, is approximately 7 river miles upstream of Montevideo, Minnesota. The damaged area of the spillway extends approximately 2,500 feet from the dam.
Description
The Lac qui Parle flood damage reduction project includes the dam and spillway construction performed by the Work Progress Administration. Operation of the project was transferred from the state of Minnesota to the U.S. Army Corps of Engineers in 1950. The original authorized purposes were water conservation and flood control, but the related structures are currently operated to support recreation, fish and wildlife management, and water supply management.
The emergency spillway is a 2,500-linear-foot earthen structure with an embedded concrete I-wall on the upstream side to control seepage and hand-laid grouted riprap on the downstream side to reduce scour. The bituminous surface of County Highway 33 makes up the top of the spillway. While the spillway experienced overtopping events in 1997, 2001, 2009, 2010, 2011, 2019 and 2023, the spring flood of 2019 was the event with the longest duration. This event resulted in deteriorating grouted riprap due to water entering cracks and eroding the road shoulder and supporting soils under the riprap.
Status
The spillway is eligible to be listed on the National Register of Historic Places, and coordination with the State Historic Preservation Office is ongoing.
The St. Paul District awarded an Architecture and Engineering Services contract to a Stanley-Stantec joint venture (JV). The JV developed plans and specifications, and a construction contract was awarded with limited funding September 2024. This contract covers repairs on 1,300 linear feet of the spillway. Construction is currently underway and is expected to be complete in spring 2026. Construction was delayed due to high water, and temporary flood protection was installed to reduce the risk of an overtopping event. Funding has been obtained to advertise a construction contract for the remaining 1,200 linear feet of spillway. A contract is expected to be awarded for the remaining section (Phase 2) by the end of calendar year 2025.
Authority
The dam is part of the Lac qui Parle Project authorized by the Flood Control Act of 1936 (Public Law 74-738).
Funding
This project is funded with 2019 Emergency Supplemental Funding and fiscal year 2021 and 2022 work plan funds.
Engineering and construction supervision and administration (allocated funds) $1,300,000
Phase 1 construction (allocated funds) $6,000,000
Phase 2 construction (allocated funds) $8,000,000