The Vermillion River used to snake naturally across Scott and Dakota counties, before farmers began straightening its banks more than 80 years ago to make their plowing easier. That hurt water quality, because a straight river erodes its banks more quickly, dumps more silt and reduces the oxygen that fish need to thrive.

To improve the Vermillion's water quality and enhance its trophy brown trout fishing, a group of agencies now has created a new meandering course along nearly a mile of the river east of Farmington.

The new section, which cost about $420,000 to construct, was dug along the Vermillion last winter and connected to the river this summer, officials said. Fill from the new stretch in Empire Township was dumped into the old, dried-up course after the water was diverted. The work was finished this month.

Tree trunks were buried in the banks with root stumps protruding to offer cover for fish and the insects they eat, Brian Nerbonne, a trout stream specialist, said during a recent tour of the new waterway.

"It's more habitable for fish," said Nerbonne, of the state Department of Natural Resources. The agency worked with Dakota County, the local watershed and others on the project.

He said the meandering flow creates deep pools at river bends, which trout like. Instead of dropping silt on the bottom, where trout spawn in gravel, the new channel drops more silt on the banks. Besides suffocating trout eggs, bottom silt creates a shallower, warmer river that is not so conducive to trout.

"Trout require the cleanest environment of any fish species," said Ed Twig, of Twin Cities Trout Unlimited, which installed open-ended oak boxes and other trout cover in the new stream. "They need cold, clear water." He said the meandering creates riffles, which mix in more oxygen for fish.

The DNR designed and oversaw the project, which received its major funding from state Legacy Amendment tax revenues, the state Environment and Natural Resource Trust Fund and the Vermillion River Watershed Joint Powers Organization, a Dakota and Scott counties agency.

The state and county bought the 500-acre Miles farm in the area some years ago, said Travis Thiel, a watershed specialist for the county. He said the habitat for brown trout, for which the Vermillion is known, was poor in the filled-in area due to the straightened course.

"The county and watershed have an interest in recreational opportunities for residents, and it should be good quality," Thiel said. He noted that hunting is also permitted in the project area, which will gain a few more duck ponds from the project.

The old waterway had become wide, shallow and slower because of silt buildup. Nerbonne said the new section is narrower, which causes the river to flow faster, deeper and colder. He noted that 125 trees, including maples, oaks and cottonwoods, were planted along the banks. The banks were girded with a coconut mesh to hold soil until plants get established.

The new course is almost 3 miles east of Hwy. 3 on 200th Street (County Road 66), and up a dirt lane marked with a sign for a DNR wildlife management area.

Nerbonne said similar remeandering projects have been created on Valley Creek in Afton and the Old Mill Stream in Marine on St. Croix, both in Washington County.

Jim Adams • 952-707-9996