The Minnesota River is what carries most of the sediment visible in the Mississippi-St. Croix confluence. Most of the Minnesota flows through corn and soybean farm country in the southern and western regions of the state. It also flows through loose glacial material that easily erodes. He donated it to the St.
Croix Watershed Research Station, which has studied water in all three rivers extensively. Croix and upper Mississippi have their share of water quality challenges, but both carry far less sediment.
They also both flow partly through forested landscapes without as much intensive agriculture or erodible soils. Croix River Association. Ultimately, the reasons two rivers can look so different is more complicated than it first appears.
Croix builds support for river stewardship, and connects people and organizations. It is an independent news source produced by Greg Seitz, with past support from the St. Donate to St. Croix today ». One of the biggest challenges facing the St. Croix River is harmful blooms of algae in in the lower river, due to excess nutrients in runoff. Learn more ». Croix is powered by a broad community of St. The sawmill era ended in , when the last log raft limped down the St.
The river became, once again, pristine. In much of the 20th century, the population of the metro area mushroomed. Along with barge traffic, train lines paralleled the Mississippi to St. Paul and Minneapolis.
The growing cities flushed their toilets directly into the river. When the first lock and dam was built in Minneapolis in the s, sewage began to back up behind it, said Norman Senjem, Mississippi River Basin coordinator for the Minnesota Pollution Control Agency. By the s, the Mississippi in Minneapolis was dead. The oxygen had been soaked up by the rotting filth and garbage, leaving the fish and plants to die.
That river was built to pollute. Geologist Jennings said it is still adjusting to the departure of glaciers—meaning it is still digging itself deeper into its own gorges, in a way that the Mississippi and St. Croix have already done. The Mississippi picks up sandy soil, which settles out of water quickly. But the Minnesota travels though areas of clay, which creates fine silt that can linger for weeks. From the s to the s, they converted thousands of acres of prairie in the Minnesota River basin into farmland.
Land that was once a sponge began to shed water like a tin roof. Today the mocha-colored runoff pours into the Minnesota, which in turn makes the Mississippi look dirty. Paul for the first time and suddenly the water turned brown. Since then, regulators have tracked down pollution coming from specific points, such as factories, power plants, sewage plants.
And they have all but solved the problem of urban runoff—the source of a mere 10 percent of solids in the Mississippi today. In , the 72 miles of river that run through the Twin Cities area became a national park just like Yellowstone, according to Paul Labovitz.
That national park stretches over 54, acres, about 1. It overlaps many other local and state parks. The park service and about 30 local governments now regulate development along the riverbanks.
Meanwhile, the already clean St. Croix just kept getting cleaner. In , the federal government gave it the gold standard for protection—the coveted Wild and Scenic River designation. Regulations on both rivers have expanded beyond issues of water quality into what the land looks like when viewed from the river. They limit, for example, any new building on the water and the height of buildings near the river.
Labovitz said the Mississippi from the Ford Dam to Hastings is a world-class walleye fishery. He and a boatful of friends recently went fishing near the dam. Mississippi boosters look with envy at the St. Croix, which has at least three thriving canoe-rental businesses sending thousands of people canoeing annually.
Croix-style restaurants and marinas? River-friendly businesses would draw more users and create jobs, he said. The city of St. It envisions a new street-level balcony overlooking the Mississippi, at the present site of the Ramsey County Jail and the former West Publishing Building. The city is interested in installing new eateries at Watergate Marina, which is in Crosby Farm Regional Park, and in an abandoned grain elevator across from Harriet Island.
Has it always been this way? For help answering her question, we reached out to Trevor Russell, water programs director of the nonprofit advocacy group Friends of the Mississippi River. Russell said the answer to that question depends on where you are.
From its headwaters at Lake Itasca and down through northern and central Minnesota, the Mississippi River is relatively clean and clear. In southern Minnesota, the Mississippi looks much murkier than it does up north. As the river meanders past St. Cloud and the Twin Cities — and eventually flows down to the Gulf of Mexico, it often appears yellowish-brown and is sometimes called the Muddy Mississippi.
Paul, the murky Minnesota River flows into the relatively clear Mississippi. The Minnesota River carries a lot of sediment.
It runs off farm fields and or washes into the river from eroding stream banks. Researchers estimate that about three-fourths of the sediment in the Mississippi River in the southern part of the state originated in the Minnesota River. Adding to that are the extensive farm drainage systems in the Minnesota River valley. The systems are designed to prevent crops from drowning during a wet spring or fall, Russell said. But they also bring with them a lot of runoff.
South of the confluence with the Minnesota, the Mississippi looks a lot muddier. The color of a river doesn't necessarily indicate whether it's polluted, Russell said. However, when sediment creates cloudiness in the water, organic matter and pollutants such as phosphorus and nitrogen can attach to the fine particles and get carried downstream.
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