The Minnesota Nature Conservancy is launching a $10 million fund dedicated to showing that the best way to protect the Mississippi River and the Twin Cities' drinking water is to use nature itself.

The Upper Midwest chapter of the international conservation organization on Friday announced the creation of the private Minnesota Headwaters Fund. Over the next three years it will raise money to pay for targeted protections, such as conservation easements and streambank protections, around the four rivers that are the Mississippi's primary tributaries: the Crow Wing, the Pine, the Sauk and the Rum.

Ecolab Inc., a Minnesota-based water technology company, was the first to donate, with a contribution of $500,000. The money will be used to keep forested land in its natural state, restore wetlands and flood plains, and protect stream banks.

The move is another example of how the state and environmental groups are scrambling to protect the still-healthy aquifers and rivers that supply Minnesota's water for drinking, industry, agriculture and recreation.

On Thursday, the Minnesota Department of Natural Resources announced it had reached a deal designed to protect sensitive groundwater and pine forests in the same area of the state. North Dakota-based R.D. Offutt Co., the nation's largest potato grower, agreed to scale back ambitious plans to replace pine forests with potato fields over concern that they could contaminate a large aquifer with fertilizers and farm chemicals.

Both moves are designed to slow what many see as an alarming rate of development and deforestation to expand agriculture in Minnesota, much of it in areas that were never considered at risk. Between 2008 and 2013 some 400 square miles of forest, wetland and grasslands in the Upper Mississippi River Basin were converted to agriculture, much of it in areas that are significant sources for drinking water for more than a million people in the Twin Cities and St. Cloud, according to an analysis by the Nature Conservancy and the University of Minnesota. By one national estimate, that is the second-highest rate of deforestation in the country.

They also demonstrate a different environmental strategy — that it makes more financial sense to preserve clean water and natural landscapes than to clean up pollution after it happens. In other parts of the state, some communities are spending millions to remove nitrates and other contaminants from their drinking water.

"The idea is to be able to demonstrate that natural infrastructure has benefits for drinking water," said Doug Shaw, assistant state director of the Nature Conservancy in Minnesota. "[It] ensures our relatively low water treatment costs stay that way."

The money will be used for projects like restoring degraded stream banks along the Rum River, which empties into the Mississippi just above the intake pipes for the Minneapolis drinking water system, Shaw said.

"More of our water comes from the Rum than Mississippi," he said.

Plans call for re-establishing 20 to 40 miles of stream banks and flood plains, with 5,000 to 6,000 acres of legal easements that would prohibit development in the future.

The Nature Conservancy would also sponsor scientific research on water quality, fish and mussels to prove that the strategy works to protect and enhance water quality.

But $10 million will not go far in the increasingly coveted 20,000-square-mile watershed that covers the middle of the state.

Shaw said that he hopes to combine the private money with state and federal funds to "scale up" protections.

The Minnesota Headwaters Fund is an example of a strategy that's been used elsewhere to protect drinking water sources. A water protection endowment funded by industry and other large water users in Quito, Ecuador, was launched with $21,000 and has grown to $8 million. In Santa Fe, the Nature Conservancy established a fund to manage the land around rivers to prevent large forest fires that could contaminate the water.

But Shaw said that the Minnesota fund is unusual in that it's designed to preserve what isn't broken.

"We are preventing problems as opposed to having a crisis," he said.

Josephine Marcotty • 612-673-7394