A new study of the upper Mississippi River suggests the economic benefits of preserving critical land in the river's headwaters region could significantly outweigh the cost.

The nonprofit Nature Conservancy partnered with St. Paul-based Ecolab on the report. It underscores efforts to protect and restore land in the Upper Mississippi watershed, which stretches from the headwaters at Lake Itasca to the Twin Cities.

The report highlights growing threats to the river's water quality, including forests being converted to cropland or development.

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"We are increasingly concerned that the land use changes that we've seen will start to have effects on our water quality," said Doug Shaw, assistant state director of the Nature Conservancy. "We think this is a great time right now to start to build an economic case as well as a good conservation case for protecting the headwaters."

The Nature Conservancy has identified 108,000 acres in the 13 million-acre Mississippi headwaters it believes should be preserved through purchases or conservation easements, and another 100,000 acres that it believes should be restored to grasslands or wetlands. The lands were chosen based on their value to wildlife habitat, drinking water sources, groundwater protection or reduced soil erosion.

The report found that protecting about 200,000 acres in the watershed from development or conversion to farmland would cost $400 to $600 million, but it would yield nearly $500 million in direct and indirect economic benefits.

The report estimated direct benefits at $130 million, including lower costs for cities to treat drinking water, higher property values and jobs in the tourism industry. It also indirect benefits including wildlife biodiversity, cleaner air and fewer carbon emissions.

The report says the protection efforts also would save future cleanup costs if the Mississippi were to become polluted. The river is the drinking water source for 1.2 million Minnesotans.

"If the river becomes more and more deteriorated — if it gets to the point, for instance, where the Minnesota River is today — it could cost us billions of dollars to fix it to clean up, to restore it over time," Shaw said.

Doug Baker, CEO of Ecolab, said the upper Mississippi River is in fairly good condition, but that could change due to threats from deforestation and industrial development. He said stopping pollution upstream will have a big multiplier effect downstream.

"Right now, the Mississippi is in a state where frankly, it's quite cost-effective to prevent it from spiraling the wrong way," he said.