Most people know spawning salmon migrate from the ocean back to the rivers and streams where they were born. Something similar happens in the Red River basin and other basins in Minnesota. Fish that spend most of their time in the main part of the Red will, during spawning season, go searching for good habitat by swimming up the Red’s tributaries.
At least they used to.
Some of the best spawning habitat in the basin is located upstream in the Sand Hill River in what’s known as the beach ridge area — a transition zone where thousands of years ago retreating glaciers left behind gravel and other features that make fish hot to trot. The problem is getting there.
Fish on the make can’t move up the Sand Hill without literally running into concrete walls. Over the years, the river’s natural meandering shape was straightened and channeled. But doing this sped up the flow of water and increased erosion and flooding. In an attempt to control these impacts, four dams were installed in the Sand Hill. These structures did not really do much to prevent problems but instead have caused several environmental issues, including preventing fish from reaching good spawning habit upstream.
Evidence of this is captured in the Sand Hill River Watershed Biotic Stressor Identification Report recently published by the Minnesota Pollution Control Agency. Agency staff conducted on-the-ground surveys to record conditions in the watershed that pose a threat to aquatic life: fish, aquatic insects and other creatures. In addition to the problem of fish being prevented from moving upstream (known as loss of connectivity), the report identified issues with:
- Too much sediment and too little dissolved oxygen
- Alterations that have caused the river to have very high flows during spring runoff and summer rain events and very low or no flow late in the summer and fall
- Poor habitat (caused by a variety of factors)
Specifically, the report shows many species of fish were only found downstream of dams or other control structures, including larger fish such as channel catfish, walleye, rock bass, goldeye and sauger.
The Sand Hill River Watershed District, in cooperation with the Minnesota Department of Natural Resources, has a plan to restore upstream fish migration in the Sand Hill by modifying the dams. The goal is to complete this work by transforming the barriers into a series of riffles that pose little hindrance to fish bent on finding fertile habitat in the 50 miles of the river located upstream of the dams.
Reconnecting this substantial spawning and rearing habitat will improve the composition and quality of the fishery both in the Sand Hill River and the entire Red River basin. The work is expected to help efforts to re-establish lake sturgeon in the basin.