A fisheries agent released thousands of fingerling brook trout into an Afton stream Wednesday in a milestone achievement after a years-long effort to repair damage to the stream brought by decades of logging, agriculture and development.

The Minnesota Department of Natural Resources will re-stock the fish in Trout Brook for two or three years and then observe whether or not it can persist on its own, said east metro area fisheries supervisor T.J. DeBates.

The waterway is fed by a 5,500-acre watershed of forest and agricultural lands, and it cuts across Washington County before emptying into the St. Croix River. The changes that made the stream unsuitable for life included erosion from 19th-century logging in the area that dumped 10 to 15 feet of sand into the lower portion of the stream. Some sections of the creek were straightened and made into roadside ditches. Erosion along the brook's banks meant sediment and excess nutrients ended up in Lake St. Croix.

The repairs to Trout Brook included "re-meandering" sections of the stream, allowing water flow to slow and create life-sustaining pools for aquatic species. Two culverts that were perched above the water's surface, creating a waterfall effect that made it difficult for fish to migrate up the stream, were replaced. Shoreline stabilization and in-stream habitat structures were added as well.

The project was carried out with the combined efforts of the DNR, the South Washington Watershed District, Great River Greening, Afton Alps and its owner, the Vail Corporation.

DeBates said the brook trout released Wednesday are their own restoration story, coming from a strain of Minnesota trout found in the state's Driftless Area.

The DNR conducted years of sampling and genetic testing to find a native strain of trout amid the many strains introduced from outside Minnesota during past restocking efforts. The search began 20 years ago but it was only recently that the Minnesota strain, called Minnesota Driftless, was finally available for stocking after being raised at the DNR's Peterson Hatchery.