Open Water including Lakes and Rivers

Throughout Metro: Open Water - Including Lakes and Rivers

The open water habitat type includes both shallow and deep-water lakes, rivers, streams and their associated shorelines. Open water habitat is abundantly available within the metro area, including three major rivers (the Mississippi, St. Croix and Minnesota) and more than 500 lakes greater than 20 acres in size.

Shallow lakes often have abundant aquatic plant growth due to high nutrient content and available sunlight. Stands of emergent and floating-leaved aquatic plants as well as submerged plants are often present and provide food and habitat for waterfowl. Deep lakes typically provide large open spaces, clear water and varying levels of vegetation and productivity. The three major rivers of the metro area can be generally characterized by slower moving, warmer waters with the capacity for larger and deeper pools. The clarity level of larger rivers tends to be naturally lower than faster moving smaller streams but sedimentation load is also greatly affected by human activities. Shoreline habitats occur as linear strips along lakes, ponds, rivers, and streams. Most of these communities are sparsely vegetated because of the absence of well-developed soils.

Lakes and rivers are not only desirable as suitable habitat to birds; they are also the most sought after areas for human recreation, fishing and development. Lakeshore development, as well as chemical, nutrient, and sediment runoff from roads, parking lots, and roofs have played a part in degrading open water habitat within the metro area. Since European settlement hundreds of thousands of acres of Minnesota’s shallow lakes have been ditched and drained. In addition, many of our lakes and rivers throughout the metro area have been impacted by aquatic invasive species including curly-leafed pondweek, Eurasian watermilfoil, and more recently, zebra mussels.

Birds that thrive in open water habitats

Thirty-four species nest in these habitat types in the metro area, including 11 species of conservation concern: Trumpeter Swan, Wood Duck, Mallard, Blue-winged Teal, Redhead, Pied-billed Grebe, Black-crowned Night Heron, Spotted Sandpiper, Belted Kingfisher, Purple Martin, and Northern Rough-winged Swallow. Open water and the associated shoreline habitat is also critical to the many migrants that utilize the Mississippi River flyway in spring and fall.

Target Species

The Black-crowned Night Heron^xxiv is often used as an indicator of environmental quality, mainly because it is a widly distributed colonial nesting waterbird that is susceptible to contaminants. A fish eating bird, it shows a broad range of flexibility in selection of nesting and foraging habitats, is somewhat tolerant of degraded habitats, and has the ability to habituate to moderate amounts of disturbance, which makes it a very suitable target species for conservation in an urban environment. Conservation efforts that benefit the Black-crowned Night Heron include restoring degraded wetlands, creating 100 meter buffers around established nest colonies, using integrated pest management to reduce overall pesticide loads, and ensuring agricultural and industrial run-off are not impacting water quality and flooding low-lying nests at a critical stage during the nesting period. Black-crowned Night Herons, as well as other colonial nesting waterbirds, may also be impacted by climate change. Changes in temperature and precipitation may result in less suitable wintering and breeding habitat.

Spotted Sandpipers^xxv are an ideal target species for the open water habitat type because their breeding behavior emphasizes the use of shoreline and island habitats occurring in an open water system. Spotted Sandpipers typically nest in semi-open areas within approximately 100 meters of the water’s edge. Their nests are ground scrapes, typically created at the base of vegetation, which provides cover from predators as well as shade. Loss of shoreline habitat due to development poses the greatest threat to this fairly common and widespread shorebird.

Belted Kingfishers^xxvi favor areas with overhanging vegetation along streams, rivers, ponds and lakes. The most important habitat requirements for Belted Kingfishers appear to be open water supporting a variety of food resources such as fish and aquatic insects, as well as steeply sloped bank exposures for digging nest burrows. Water quality, cover and the availability of suitable nesting habitat are essential for breeding Belted Kingfishers. Allowing for some forms of natural, steep bank erosion, where safety and water clarity issues are adequately addressed, will provide suitable nesting habitat for kingfishers and allow them to continue to thrive in the metro area.

Conservation Actions – Open Water/ Lakes/ Rivers

• Establish environmentally-based shoreline setback regulations for commercial and residential properties built in close proximity to waterways.
• Apply seasonal water level management regimes to controlled impoundments.
• Employ erosion prevention practices in areas susceptible to high water run-off by planting native emergent vegetation, specifically around storm water runoff impoundments.
• Allow for some levels of natural stream bank erosion to take place to provide nesting habitat for belted kingfishers and bank swallows.
• Work with regulators and the fishing industry to reduce the use and availability of lead jigs and lead sinkers.
• Conduct habitat restoration of existing wetlands through invasive species removal/ control and native plantings.
• Continue monitoring of Ospreys, Common Loons and Bald Eagles for contaminants that persist in the environment.