With its spectacular views and lush landscape that make it a haven for wildlife, the St. Croix River is one of the region's most important waterways.
But the scenic character of the St. Croix, which forms the border between eastern Minnesota and western Wisconsin, has made it a magnet for rapid development -- and the pollution that comes with it.
The job of cleaning the St. Croix, part of the national Wild and Scenic Rivers system, largely falls to local officials, who increasingly are looking for ways to balance development with conservation.
About 100 such officials recently toured the river aboard the triple-decker Grand Duchess, sharing stories about how they're trying to protect it.
As the cruise ship chugged upriver from Hudson, Wis., to Stillwater, Minn., Melissa Lewis, a conservationist with the Board of Water and Soil Resources, showed off a tub of critters collected in Brown's Creek, a tributary of the St. Croix.
"This is a scud; we have an aquatic worm trying to crawl out of the tub over there in the corner," Lewis said. "Down there is a caddis-fly. This one is a stone-fly, and these are very good indicators of a healthy stream."
In spite of that good sign from one of its tributaries, monitoring of the St. Croix over the last 10 years shows that it's a river in trouble. Thanks to rapid development along the shorelines, and runoff from lawns and farms, phosphorus and algae are showing up in high concentrations.
The Minnesota Pollution Control Agency has a cleanup plan, but a lot of the work will be delegated to local governments.
Because this stretch of the St. Croix is designated as a Wild and Scenic River by the federal government, it's subject to stricter land use controls.
Each town has rules approved by the state Department of Natural Resources that define lot size and setbacks from the river and the bluff. But many people want bigger homes and better views, so they ask local officials for variances from those rules.
Earlier this year, the Minnesota Supreme Court ruled in a case brought by broadcast executive Ron Hubbard that the DNR cannot interfere in those requests.
Lakeland Mayor Brian Zeller said most cases aren't that controversial, and most are resolved by compromise.
"The regulations are the guideline or the base that local units of government build their ordinances from, or model themselves from. So there are some differences and some room for accommodation," he said. "It's really trying to find a balance."
The DNR advises local governments that they can require something in exchange for granting a variance -- insist that the homeowner install a rain garden, for instance.
Rain gardens are big in Stillwater. Torry Kraftson, a city engineer, said he's trying to find ways to meet a state requirement to capture a half-inch of rain and keep it from running into the river. In the last four years, as the city has rebuilt roads, it's installed 40 rain gardens -- and Kraftson is calling on citizens to help maintain them.
The homeowners weed and add new mulch, but the city performs major maintenance, such as drainage work.
"Generally, we're getting very good cooperation from our residents," Kraftson said. "We've had a Rotary group that's come in and helped us do some weeding and planting in some of the rain gardens, which has been very helpful."
Kraftson figures he's done about 25 percent of what he needs to do to capture the half-inch of rain. He said he thinks the city can get there eventually, but it's hard to find the money to pay for it. So far, the cost is included in the road construction bill.
A rain garden may seem like a small thing, but the stakes are high. The St. Croix River is listed as impaired by the MPCA, and the group American Rivers has declared it one of the country's 10 most endangered rivers.