justnorth posted on June 14, 2007 10:41 :: 1358 Views
Progress continues on the 425-acre Lake Maria project in north-central Murray County, according to the Department of Natural Resources (DNR) and Shetek Prairie Chapter of The Minnesota Waterfowl Association (MWA).
Except for a brief period in the early 1990s when the DNR and other partners improved the lake through intensive management, the once historic waterfowl lake has been in poor condition for decades. Excessive water levels that drowned out beneficial vegetation and allowed for undesirable fish (carp, bullheads, fathead minnows, etc.) to survive over winter, and nutrient loading that caused excessive algae blooms were the primary culprits.
Fueled by the ambition of local lakeshore owner Winston Peterson, DNR partnered with Ducks Unlimited, MWA, Murray County, the U.S. Fish and Wildlife Service,and other local and nonlocal partners to implement an intensive and long-term solution to improve this lake.
In 2005, partners installed an electric fish barrier in the road culvert that contains the stream that separates Lake Maria from downstream Lake Sarah. A pump was also installed that year to allow Lake Maria to be temporarily drawn down (dewatered) under certain environmental conditions. Draw-downs are an effort to replicate the natural wet-dry cycle that no longer regularly occur due to excessive drainage and the presence of fixed-crest dams that prevent lakes from drying out.
During the draw-down process, problem fish are removed, bottom sediments consolidated, and beneficial aquatic plants restored to provide wildlife habitat, stabilize bottom and shoreline sediments, and improve water quality. The electric barrier will keep fish from re-entering Lake Maria from Lake Sarah.
Very wet conditions in fall 2005 and spring 2006 prevented using the pump to dewater the lake. In fall 2006, precipitation patterns returned to normal and the pump effectively removed nearly all water from the basin. To reduce odor problems from decaying fish, DNR staff and local commercial fisherman David LeClaire removed dead and dying fish from the lake. To ensure that problem fish would not be able to over winter in the streams entering the Lake Maria, DNR staff also applied small amounts of the fish toxicant rotenone in February.
By spring 2007, the lake was void of fish. The electric barrier is preventing fish entry into Lake Maria. In fact, during the peak of the carp migration, David LeClaire and his crew removed over 100,000 pounds of carp, buffalo and bullheads from the area immediately downstream of the electric fish barrier. No game fish were present. The pump and an auxiliary pump are presently being used to partially dewater the lake's basin again to encourage the growth of much-needed vegetation, both emergent (cattail, bulrush, etc.) and submergent (sago pondweed, chara, etc.).
The local Shetek Prairie Chapter of the MWA paid for the utilities needed to operate the pump and fish barrier in this and subsequent years.
Chapter delegate Dr. Mark Evers stated, "It's been great to see our contributions to the Lake Maria Restoration Project in action and starting to make a difference. Keeping lower water levels and eliminating the rough fish will quickly produce visible changes such as clearer water and thriving vegetation."
The spring dewatering of Lake Maria is nearly complete, although a small section of the draw-down channel needs to be blasted to ensure that lake water can continue to flow to the pump. Barring a very heavy rain event, most of the bottom of Lake Maria should be exposed by mid-June - the ideal time to encourage aquatic plant growth.
Attempts will be made to keep Lake Maria mostly dewatered in 2007 to allow for healthy plant growth. Biologists predict that during fall, the lake will be a magnet for migrating waterfowl due to the presence of high-quality foods, shallow waters in which to feed, and a disturbance-free environment due to low waters that prevent boat access.
During the 2008 growing season, attempts will be made to keep water levels low enough to prevent newly established plants from becoming stressed, which means that water depths will be in the 1- to 1.5-foot range. If fall rains are sufficient, Lake Maria's water levels will be allowed to return to full pool by autumn, thus providing excellent waterfowl hunting habitat.
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