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The elevation of 883msl represents the likely limiting depth for light penetration and <br />therefore presence ofrooted submergent vegetation. Secchi disc readings taken on <br />Round Lake through 1992 found water clarity to an average depth of around 4.5 feet <br />below the water surface (MPCA 2011). With water levels at 887.0 msl and Round Lake <br />water clarity following historical trends, sunlight will penetrate to at least this depth and <br />stimulate submergent plant growth. Sunlight penetration to this depth would promote <br />submergent vegetation over about 75% of the lake bottom. Joarnt and Kenow (1978) <br />observed rooted submergent vegetation to this depth coincident with the time period <br />when Service staff observed the highestwaterfowl use on Round Lake. Recent sampling <br />found water clarity to 5.5 feet(USFWS 2013). <br />The Round Lake basin configuration is shown in Figure 4(Wenck 2011).This configuration is <br />based on 2011basin mapping.Figure 5 shows how the key elevations identified above are <br />distributed throughout the basin. <br />A general concept for water level management on Round Lake would be similar to what we do <br />on other wetland basins of this type on the Refuge and is described below: <br />Remove stoplogs to bring the water levels down as soon as possible in early spring to <br />facilitate light penetration to the maximum depth. This facilitates the germination of <br />emergent and submergent vegetation and also exposes flats for migrating shorebirds, and <br />consolidates muck and detritus. <br />Hold the water at this level through mid-summer to allow successful nesting of water <br />dependent birds. After the over water nesting species fledge, gradually bring water levels <br />up to a level that will promote maximum submergent plant growth without drowning out <br />or uprooting the emergent plant growth that hasbegun in the more shallow areas of the <br />basin. <br />Hold the water at this level until fall when the seed, which provides a food source for <br />migrating waterfowl, matures on annual emergent plant species and migration <br />approaches. <br />Raise water levels up to the optimum depth for fall waterfowl migration. This targeted <br />optimum water depth is where the majority of the seeds produced through the summer are <br />at a depth above or below the water’s surface that can be accessed by the waterfowl. <br />Water levels oftenare increasedinsmall increments through the fall migration season as <br />food resources are eaten out. Increasing water levels makes new areas accessible and <br />providesa continuous food resource. <br />Undertypical water management scenarios,water levelscan fluctuate anywhere from 2 to 5 feet <br />depending on the basin configuration. Due to the capability of the water control structure that is <br />currently in place on Round Lake, we expect that water levels would be actively managed to <br />fluctuate 2 to 3 feet, or less.Rapid changes in water levels would be counterproductive to <br />establishing and maintaining vegetation and, therefore, wildlife management success. In <br />addition, water levels are generally not manipulated every year. Typical water management <br />employs the manipulation model outlined above every 3 to 5 years. <br />8/6/2013 11 USFWS RLMP <br />