Fish that spend most of their time in the Red River will, during spawning season, go searching for good habitat by swimming up the Red’s tributaries. 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. This area is a transition zone where thousands of years ago, a glacial lake called Lake Agassiz retreated and left behind gravel and other features that make fish today “hot to trot.” The problem for the fish was getting there.
In more recent history, people have straightened and channelized the Sand Hill River’s natural shape. Doing this sped up the flow of water, increasing erosion and flooding. In an attempt to control these impacts, four concrete drop structures were installed in the 1950s. These structures did not really do much to prevent problems, but instead caused several environmental issues, including preventing fish from accessing many miles of prime spawning habitat in the beach ridge area.
This issue came to light in the Sand Hill River Watershed Biotic Stressor Identification Report completed a few years ago. Scientists from the Minnesota Pollution Control Agency conducted on-the-ground surveys to record conditions in the watershed that pose a threat to aquatic life: fish, aquatic insects and other creatures. The report showed 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.
To help reduce erosion problems called head cutting and bank sluffing, and at the same time address the fish barrier problem, local partners installed a series of rock riffles bordered with rip rap that replaced the concrete drop structures. The stretches of riffles have flat enough slope to allow fish passage upstream across each structure.
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 also expected to help efforts to reestablish lake sturgeon in the basin.
The primary funding for the project came from Minnesota’s Clean Water, Land and Legacy Amendment. The West Polk Soil and Water Conservation District (SWCD) secured a $475,000 grant from the Minnesota Board of Water Soil Resources’ Clean Water Fund. This grant required a 25% minimum match, which was provided by the Sand Hill River Watershed District and a $100,000 Enbridge Ecofootprint Grant.
For details, including drone footage of the riffles and riprap, see project webpage on the watershed district’s website.