Zumbro Watershed

Zumbro Watershed. . , Changing the Land Changes the River , Over the past 150 years we have changed the landscape to create cities and farms. These changes increased how much water runs off the land. More runoff means more erosion, pollution, and flooding., The Historic River , In the 1850s, the Zumbro River was a shallow, crooked, slow flowing, and gravel-bottomed river. It had wide, sloped banks covered with prairie grasses and wildflowers. Captain Andrew Talcott described the river near today's City of Hammond in 1820 as "30 yards wide, 5 feet deep, with a stony bottom and wide banks.", The Early Settlement River , European-American settlers changed the Zumbro Watershed landscape. They changed forests and prairies into towns, pastures, and crop fields. They built dams to power flour mills and to create recreational lakes., The Modern River , Today's Zumbro River looks very different than it did in 1820. The 1972 Federal Clean Water Act imposed regulations on factories and cities, significantly limiting the pollution being piped into the river. However, the Act does not regulate runoff pollution from small towns and crop fields. While factory and wastewater pollution has decreased, runoff pollution in rural areas continues to increase., Erosion and Sedimentation , Increased runoff from cities and farm fields creates deeper, faster flowering rivers that cut into the riverbanks and dig down into the riverbed., Every mile of the Zumbro River has some bank erosion. All the river's artificial lakes (created by dams) are filling up with sediment. Governments and taxpayers are spending millions of dollars to dredge lakes and ponds in the region., Flooding , Severe floods, which were rare before 1940, are now increasingly common. There were four major floods in the watershed between 2000 and 2010., Many farm fields absorb and hold less water than they did 100 years ago. So when it rains in the Zumbro Watershed, more of the rain that used to stay in the soil flows quickly to the river., Chemical Pollution , When rain falls on cities and rural areas, it can pick up and carry chemicals from the landscape into our waterways. Salt (from roads) and nitrates (from farm fields) are increasingly common pollutants in area rivers., Current clean water laws address "pipe source" pollution from factories and wastewater plants, but they do little to address "runoff pollution" from cities and farms., Drinking Water , Most communities in the Zumbro Watershed get their drinking water from underground aquifers. River water and polluted runoff can leak into aquifers and affect water quality., Nitrate pollution in wells was almost unheard of prior to 1970. Today, 25% of tested private wells in Olmsted County contain unsafe levels of agricultural nitrogen or coliform bacteria pollution. City wells continue to provide clean drinking water for residents., A Concise Zumbro Watershed History , Pre-European Settlement , Oak savannah, prairies, and forests covered the region. , The 1910s , A diversified mix of small grains, hay, pasture, and corn crops were common in regional farms. The population of Rochester was 7,844 people in 1910. The average Zumbro River flow at Zumbro Falls was 384 cubic feet per second in 1911. , The 1940s , Improved technology supported mechanized family farming and large-scale drainage projects. Floods were more common. Up to 50% of all farmland was in perennial crops like pasture and hay. Rochester's population was 28,312 in 1940. The average Zumbro River flow at Zumbro Falls was 408 cubic feet per second in 1941. , The 1970s , Corn and soybean farming dominated the region, chemical fertilizers and pesticides became widespread, and many pastures and hay fields disappeared. Rochester experienced two major floods. In 1972, the Federal Clean Water Act regulated pipe source (point source) pollution. Land use pollution (runoff), from cities and farms continued to increase. Rochester grew to 53,766 in 1970. The average Zumbro River flow at Zumbro Falls was 728 cubic feet per second. Nitrate levels in the Middle Fork Zumbro River, in Oxbow Park, were 2.6 parts per million in June 1970. , The 1990s , Rochester flood control projects created reservoirs and a wider river to "Slow the Flow" of water through the city. These projects reduced river flow out of the city by 18% and were succesful in protecting the city and downstream communities from flooding. , The 2010s , The Middle Fork of the Zumbro River experienced a 500-year flood event in September 2010. Significant flooding occurred in Pine Island, Zumbro Falls, Hammond and other communities in the area. Only 15% of farmland was in perennial crops like hay and pasture. The population of Rochester grew to 106,769 in 2010. Nitrate levels in the Middle Fork Zumbro River at Oxbow Park in June 2016 climbed to over 15 parts per million, a 570 percent increase over 1970 levels. Nitrates were increasingly found in private drinking water wells., , Flooding: A Water Traffic Jam , We used to think of flooding as a "natural" disaster like a tornado or a hurricane. But there's increasing evidence that human land use decisions are leading to larger and more frequent floods., The 2010 Zumbro River Flood , Zumbro Falls during the 2010 flood. , On September 22-24, 2010, up to 10 inches of rain fell in southeast Minnesota, leading widespread flooding on the Zumbro River in Pine Island, Oronoco, Zumbro Falls, Hammond, and other communities. The water was 10 feet high on Main Street in Zumbro Falls. Two-thirds of Zumbro Falls homes flooded in the largest flooding event in city history., Increased Runoff = Increased Erosion and Flooding , Ponds, wetlands, and vegetation (grasslands, forests) capture rainfall and runoff. Landscapes that don't have ponds or vegetation, like cities and empty row crop fields, allow water to run quickly into rivers. This leads to increased river flow, erosion, and sometimes, downstream flooding., The average flow in Southern Minnesota rivers have increased by 50-100% over the past 100 years. The landscape no longer absorbs rain like it used to., Large flood events used to be relatively rare in the Zumbro Watershed. Since 1940, floods have become larger and more frequent., Reducing or Eliminating Flooding Events , Since we can't control how much rain falls and where it lands, the only way to address flash runoff and flooding events in the Zumbro Watershed it [sic] by trying to "Slow the Flow" of that runoff to a more historical speed. Large cities, small towns, and individual landowners have been doing just that. You can do the same in your community., Rochester Slot Dam , The City of Rochester, after facing two devastating floods in the 1970s, worked with state and federal agencies to create water reservoirs, slot dams, and a wider river bed. These flood control measures "Slow the Flow" and reduce river flow out of the city by 18%. Since the completion of flood control structures, the City of Rochester has not flooded., Zumbro Falls Water Control Basins , After the 2010 flood, Zumbro Falls city officials worked with state and federal agencies to buy out flooded properties and install water control basins to reduce the damage from future floods., No-till Farming , Mazeppa Corn and Soybean Farmer Rod Sommerfield expected to see erosion damage on his fields after the record rainfall of September, 2010. Fortunately for him, the no-till farming techniques that he had been using for years made his fields more porous and better able to absorb and hold rainfall without eroding or flooding., This Is What Conservation Looks Like , Many farmers use conservation practices on their land to protect soil, absorb rainfall, and keep our rivers clean. Here are four practices you can see as you drive through the countryside., Fall, Winter, And Spring , Grassed Waterway, Crop Residue , A grassed waterway (green) protects a field from gully erosion while the crop residue (tan) protects the field from sheet erosion and helps the field absorb more rainfall., Cover Crops , Have you ever seen crop fields turn green in the fall, winter or spring? If so then the farmer probably planted a cover crop on that field. Cover crops absorb nitrogen, help soil to absorb more rainfall, and protect the soil from washing away in a rainstorm., Year Round , Contour Strips , Contour strip farming uses alternating strips of annual (corn or soybeans) and perennial (grass or alfalfa) crops on a field. The perennial crops absorb more rainwater and protect the soil better than annual crops do., Farm Ponds , Farm ponds (or grade stabilization structures) capture rain and snow runoff and hold it. This lets the water soak into the soil or flow more slowly into a nearby river or stream.