The U.S. Army Corps of Engineers, St. Paul District, released the draft Environment Assessment for the Big Lake habitat rehabilitation and enhancement study, Oct. 12. 

Lower Pool 4 - Big Lake Habitat Rehabilitation and Enhancement Project

Big Lake placemat

Click to enlarge 


Pool 4, Upper Mississippi River, Miles 760.2-752.8, Wabasha County, Minnesota and Buffalo County, Wisconsin, Congressional Districts: MN-2, WI - 3


  • U.S. Fish and Wildlife Service, Minnesota and Wisconsin departments of natural resources


The Lower Pool 4 study has been separated into three phases: Phase 1 – Big Lake, Phase 2 – Robinson Lake, and Phase 3 – Tank Pond. Phase 1 – Big Lake is currently in the feasibility phase, and it is anticipated that the feasibility study will be complete in 2024. Phase 2 – Robinson Lake will start the feasibility phase in 2023. Phase 3 – Tank Pond does not have an anticipated start date for feasibility at this time.


The overall goal of the Pool 4 HREP is to maintain/enhance/create quality habitat for native and desirable plant, animal, and fish species.

The Lower Pool 4 study area encompasses approximately 9,382 acres of open backwater, meandered side channel, main channel border, and island formations from state Highway 25 (Nelson Dike) at Wabasha, Minnesota, to Lock and Dam 4 near Alma, Wisconsin. It includes the main stem of the Mississippi River and portions of the Buffalo River. The site lies within the Upper Mississippi River National Wildlife and Fish Refuge.

Sedimentation of the backwaters is an ongoing issue in this study area. Big Lake has lost much of its island complex and forest to wind and wave erosion. The barrier islands between the lake and Catfish Slough have been degraded and/or eliminated over the past several years. Tank Pond near the mouth of the Buffalo River has relatively poor water quality due to a lack of water circulation and lower abundance and diversity of underwater vegetation. Overwintering fish habitat in and below Big Lake is limited, in part, by high current velocities. The existing desirable overwintering areas appear to be filling with sediment and are exposed to flows that are more frequent. Without the implementation of forest restoration measures, continued decline.

In Lower Pool 4, the Upper Mississippi River Restoration Program (UMRR) is starting with the Big Lake HREP. The Big Lake study area is from about RM 760 near state Highway 25 (Nelson Dike) near Wabasha, Minnesota, to about RM 757.5 (Figure 1). The site lies within the Upper Mississippi River National Wildlife and Fish Refuge.

Interactive Storymap