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What the Information Tells Us About Bennett Lake <br />The most significant findings regarding Bennett Lake and its watershed are as follows: <br />■ Bennett Lake has poor water quality, characteristic of many urban lakes. <br />■ An important contributing factor influencing the nutrient - enriched condition of the <br />lake is the high nutrient loads from its large, mostly urbanized watershed. Another <br />likely factor is the prevalence of the exotic aquatic weed curly -leaf pondweed, which <br />effectively "pumps" phosphorus out of the sediments ands releases it into the water <br />column during its annual die -off in the middle of the summer growing season. <br />■ Based on modeling and other observations, a 40% reduction in phosphorus loads to <br />Bennett Lake would be needed in order to bring in -lake water quality up to the Grade <br />C range (average water quality for this region) on the Met Council's scale. This is a <br />very large reduction and is likely to be achieved only with significant and expensive <br />infrastructure changes and intensive management activities in the lake itself. <br />■ The aquatic plant community is dominated by a few aggressive natives as well as <br />exotics. This is likely due to both historic water level fluctuations in the pond and <br />nutrient enriched conditions. <br />MANAGEMENT OPTIONS <br />General Comments <br />SETTING EXPECTATIONS FOR SHALLOW LAKES <br />The pristine state of most shallow lakes is one of relatively clear water and a diverse, rooted <br />aquatic plant community usually dominated by relatively small -sized plants. While algae are <br />present, they are not sufficiently abundant to create the turbid water conditions sufficient to <br />shade out the rooted submerged plants. The increase in nutrient loading that often occurs with <br />the development of the lake's watershed changes this situation. The lake shifts from clear to <br />turbid water, and with this decrease in water clarity, submerged aquatic plants disappear. <br />Restoration of turbid shallow lakes to the clear vegetated state is difficult. Reduction of nutrient <br />loadings from the watershed may have little affect, since during the period of high incoming <br />City of Roseville 54 <br />Parks Natural Resource Management <br />