REGIONAL— A detailed new water quality analysis has confirmed what most residents of the North Country have known for years— that the sprawling headwaters of the Rainy River contain some of the …
REGIONAL— A detailed new water quality analysis has confirmed what most residents of the North Country have known for years— that the sprawling headwaters of the Rainy River contain some of the purest water in Minnesota.
At 2,954 square miles, it’s also one of the largest watersheds in the state. It’s home to more than 1,200 lakes, over 400 streams and encompasses the vast majority of the 1.1-million acre Boundary Waters Canoe Area Wilderness.
The watershed’s undeveloped nature— 85 percent is under state and federal ownership— is a key reason for the prevalence of high water quality, according to the researchers. Because forests and wetlands dominate the landscape, the streams monitored showed exceptional biological, chemical, and physical characteristics.
Beginning in 2014, researchers with the state’s Pollution Control Agency, with assistance from local soil and water conservation boards, local lake associations, Vermilion Community College and the Natural Resources Research Institute undertook the effort to examine 62 different stream sampling sites and measure more than 60 lakes in the watershed. Their findings and conclusions make up the bulk of the 377-page report, just published by the MPCA.
“Today over 99 percent of the Rainy River-Headwaters Watershed is undeveloped and utilized for timber production, hunting, fishing, hiking, and other recreational opportunities,” states the report. “The immaculate waters found within this watershed not only produce some of the highest quality fisheries in the state but also offer visitors many scenic and natural views.”
According to the research, the exceptional water quality within the watershed is due largely to the existence of the vast forests and wetlands that dominate the region, along with the relative lack of human development. Those few stream stretches showing water quality impairment, are generally limited to lower reaches, in areas of more intensive land use by humans. The stressors that appear to lower water quality include recent forest cover changes, along with urban or industrial development or the draining of wetlands. Key impairments that researchers documented in lakes or streams include high levels of sediment affecting water clarity, E. coli bacteria, and mercury in fish tissue, likely caused by fossil fuel burning and airborne deposition.
But with the exception of mercury, which is a widespread issue, impairments were the rare exception, notes the report. “The majority of the water bodies within this watershed had exceptional biological, chemical, and physical characteristics that are worthy of additional protection,” states the report’s authors.
The study analyzed each of the nearly three-dozen smaller watersheds that make up the Rainy River headwaters. Those watersheds stretched from the Seagull River in the far east, to the Lake Kabetogama watershed in Voyageurs National Park.
The analysis included testing of water quality parameters as well as the biological health and diversity of the aquatic systems represented in the streams and lakes.
Biological tests conducted by the study’s participants identified numerous sensitive fish and macroinvertebrate species in many of this watershed’s drainages and this is an indicator of good water quality, note the researchers.
Of 60 lakes tested, only one— Blueberry Lake, near Ely— failed to meet the eutrophication standards. Blueberry is a shallow lake with a relatively large catchment area, where nutrient levels and algae growth were quite high. The report notes that Shagawa Lake, in Ely, also shows the effects of urban and industrial development, but that the overall water quality is still within tolerable limits.
According to their findings, the highest quality streams, based on aquatic life, habitat, and water chemistry are: Bezhik Creek, Denley Creek, Little Isabella River, Mitawan Creek, Snake River, Jack Pine Creek, Cross River, Moose River, and the Stony River.
Impaired streams included the Ash and Blackduck Rivers which flow to Kabetogama Lake and Voyageurs National Park. The Blackduck, a small sub-watershed that flows from Blackduck Lake, was the only stream identified as not supportive of aquatic life or recreational use. Blackduck Lake maintains good water quality, but a combination of extensive timber harvesting and some potential impact from a cattle operation has eroded banks, increased the levels of E. coli to hazardous levels, reduced clarity, and significantly reduced oxygen levels downstream from the lake. The MPCA intends to conduct more research in the watershed in hopes of developing strategies to address problems on the river.
While the study found that water quality in the Rainy River headwaters is generally good to excellent, the Blackduck River impairment is evidence of the high sensitivity of that water quality to human activities. “A continued vigilance is necessary to monitor areas where developmental pressures are or will be expected to occur,” stated the study’s authors. “Point and non-point pollutants are affecting water quality and quantity in select drainages. A combination of stressors, including urban/industrial development, forest cover change, draining of wetlands/lakes, and the damming of streams, are likely contributing to the reduction of sensitive species in some stream reaches.”
You can read the full report at https://www.pca.state.mn.us/sites/default/files/wq-ws3-09030001b.pdf.