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A river story
Our state’s namesake river, the Minnesota, tells a story different from our general perception of good water quality in Minnesota’s lakes and rivers. We take pride in our 11,000+ lakes, and scenic rivers such as the St. Croix and Mississippi.
The story of the Minnesota River is one of unique geography, many challenges to its water quality, and dedicated efforts by many to make it better.
While the Mississippi may overshadow it, the Minnesota River has a great impact on the Mississippi’s water quality. Many have seen the iconic aerial photo of their confluence showing the “chocolate-brown” water of the Minnesota entering the Mississippi.
With vast amounts of study, monitoring, and scientific research over decades, scientists know a lot about the Minnesota River. Overall, it’s unhealthy — sediment clouds the water, phosphorus fuels algae growth, and nitrogen and bacteria pose health risks.
While scientists know a lot, the Minnesota River is almost invisible to most Minnesotans. When we do look, often it’s just a fleeting glance from a highway bridge over a brown, muddy-looking river.
To bridge the gap between research and public understanding, the Minnesota Pollution Control Agency recently issued a study on sediment clouding the Minnesota River. The MPCA also released studies on water quality problems and strategies to improve it for the Watonwan River watershed, Minnesota River-Mankato watershed, and Lower Minnesota River watershed.
An ancient river under pressure
Among major rivers in the U.S., perhaps even the world, the Minnesota River stands apart in its formation and current challenges. Once a massive, pre-historic river, today its remnant strains under pressure from its geography, geology, surrounding land use, and changing climate.
About 12,000 years ago, a vast glacial lake covering much of central Canada and northwestern Minnesota broke through the landscape around present-day Ortonville.The resulting river burst forth in what must have been a cataclysmic event.
Like pulling the plug on a huge bathtub, a flood of water cut a mile-wide channel through the fine, fertile, glacial-till soil covering much of south central Minnesota. More than a hundred feet deep — in some places down to bedrock — it flowed to the southeast where the landscape around Mankato caused a 90-degree turn to the northeast.
As the Glacial Lake Agassiz drained and river levels dropped, ancient tributaries created waterfalls from the prairie. Today, its 13 major tributaries continue the process of cutting down from the prairie to the present Minnesota River bed. A natural process, in recent years it has intensified as a result of artificial changes in hydrology, and increasing rainfall due to a changing climate.
Prior to European settlement, countless wetlands, lakes, and prairie potholes covered much of the 14,000-square-mile river basin. They filtered and slowed the water entering the river. As land use changed to urban development and agriculture, drainage via ditches and tile lines removed more than 90% of the prairie wetlands. Water quality in the river suffered from this vast change in hydrology. The result? Increased amounts of sediment and excess fertilizers running into the river.
Cleaning up the river continues
Concern about the river’s water quality goes back decades. In a landmark event in the early 1990s, Governor Arne Carlson famously stated a goal of “cleaning up” the river in 10 years. Since then, numerous studies lay out the conditions and causes of the Minnesota River’s current state. Years of testing water quality and aquatic life in the Minnesota River provide overwhelming evidence of the adverse impacts of human development and land use around the river.
Today, we face a paradox of managing the landscape for productive agriculture, while working to reduce negative impacts on water quality. We have significant funds, tools, and technology: Restored wetlands, buffers, conservation farming, crop diversity, managed drainage, municipal and industrial wastewater treatment, stormwater management, and a growing appreciation for good soil health.
Much work is taking place. Many farmers are exploring no-till farming methods and using new tools to refine fertilizer application. Cities and industries have improved wastewater treatment, reducing phosphorus (a major algae producer) significantly. But we need to do much more.
If we can continue the cycle – monitoring, targeting efforts, identifying the tools, engaging citizens, and doing the work – there is hope for a healthier Minnesota River.