Just east of Farmington, a half dozen people in thick waders stand nearly waist-deep in a bend of the Vermillion River. They're getting ready to send electric shocks through the water. They're looking for trout.
A gas motor perched on a small boat produces power for the electric current. Two men are holding long poles with rings at the end. Current travels through the rings to the water. Following the shockers are people with nets, who haul the stunned fish out of the water and dump them in a water-filled bucket in the boat.
When about 10 fish of all sizes are swimming in the bucket, the workers pull the boat to the side to count and measure them.
"You can see on the one he's pulling out right now: it's a male -- it's got that big hook-jaw on the front," says DNR trout habitat specialist Brian Nerbonne.
"532," one of the workers calls out, as he struggles to hold the big trout against a board with a measuring tape attached.
"These are millimeters," Nerbonne says. "That's about 21 inches."
Nerbonne is a happy man. He's collecting a healthy batch of trout today. He's been counting trout, and improving trout habitat here, for years. He figures the big ones they're finding today are about six years old.
"Fish grow really fast in the Vermillion," he says. "Unlike many other trout streams, the Vermillion has a lot of a other fish; suckers, creek chubs, and things like that, they can eat. They grow a lot faster eating those other fish than if they were just eating bugs."
Nerbonne and the other DNR workers are glad to see so many young trout.
"We had low water this summer with the drought, so I was wondering how many fish we'd see," he says. "Those younger fish are sensitive to higher water temperatures. I'm glad to see we're getting good numbers of young fish."
Biologists regard trout as a kind of canary in the coal mine. These trout are healthy, and that's a sign that this river is healthy for all kinds of animals, including people.
As you walk along the stream, you can see schools and houses and roads literally a stone's throw from the river. Typically, development like this threatens the trout, especially when it gets any denser than about one house per acre.
Twenty years ago, a local sportsmen's group asked the DNR to designate parts of the Vermillion River as a trout stream. That would mean local governments would have to do more to protect the water quality, and not all of them were happy with the idea.
DNR Planner Michele Hanson had the task of coaxing local officials to get on board.
She did that by doing what the DNR is doing today -- shocking the river to show local officials there was something there worth protecting.
"Once everyone believed us that it's trout stream," she says with a chuckle. "Then we went out and met with every community along the river, of the section that we were going to designate as trout stream, to tell them what it would mean to them -- what changes might happen."
It would mean every town, every township and county that the river flowed through would have to make some changes in the way they developed.
Now, in some sections of the river, builders must leave a buffer as much as 150-feet wide.
They also need to avoid increasing the amount of runoff. Rainwater that sheets off roads and driveways and rushes directly into the river is too warm for the trout.
Builders are learning how to get the water to soak into the ground instead. They can build narrower streets, shorter driveways, and rain gardens and other landscaping that holds the runoff long enough that it can soak in.
One of the DNR staff who's here to watch the trout count is Joe Kurcinka, who has been keeping an eye on the protections designed by local governments. It's entirely possible to develop the area and keep the river healthy, he says.
He's excited about a new approach called "conservation development." It involves concentrating homes or businesses in one area and leaving lots of open space.
"The developers find that the property becomes more marketable...people like to be close to the natural amenities," he says. "Developers can make their money, the community gets the economic development and the tax base that they were expecting, and all Minnesotans benefit from the open space."
Pamela Belz, a developer who chairs the public policy committee of the Builders Association of the Twin Cities, says developers can live with stricter rules, as long as they make sense.
"The presence of a healthy trout stream would certainly be attractive to people, and therefore might garner more value," she says. "But let's be sure that we haven't over-regulated."
The DNR is also working to improve the stream as trout habitat. Strategically-placed boulders direct current away from the banks, and root balls of big dead trees reach into the water, stabilizing the banks to prevent erosion and offer hiding places.
Another threat to the Vermillion was from wastewater. Because of projected population growth, the Metropolitan Council had to expand its wastewater treatment plant in the area. But more effluent would have overwhelmed the little trout stream.
The Met Council spent millions of dollars to build a 12-mile tunnel to carry the treated wastewater to the much bigger Mississippi River.
It's all aimed at holding onto a rare treasure -- a healthy trout stream in a major metropolitan area.