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Lake Uwasso Task Force Summ�ry of Discussion with the Environmental Panel (12/18/96) Panel Member; Ed Musielewi2c-Natural Resources Consen�ation Service Tecz,y Noonar�-Ramsey Counry Public Works Deparnnent Tom Aeterson Ramsey County Soil and Water C'onservation District Joel Sehillin�z-5hort Eiliot and Hendrickson, fnc. Uave 7t�petillo-DNR Fislieries Weeds and algae: Aquatic ve�etation is a probletn in Lake Owasso, but less a problem than in marry local lakes. About 24�31 % of the lake haS ahundant plant growth in summer. Aquatic plants provide fish habitat, hut are a problem for boaters and swim�ners. DNR treats 2$�io of Lal:e Owasso's littoral zone with herhicides. F�erbicides are appHeci f'rom May to Jul,y. 7'his is more that the 1�% of' a lake's are�d allowed to bc treated but is allowed because of a�•andfather clause. Aquat.ic plants and algae require nutncnts for �owth. Nutrients can come from internal (lake) or external (watershed) so�uces. The relative importance �f these sources for the lake is not precisely known, but interna] sources appear to be a signiticant source of nutrients to the lake. August aigae blooms result frum v��ann water and the release of nutriettts from decaying plants in the lal:e, Fish habitat. The lalce is mana�ed by the DNR %r walleye and mnskie. 'Che lal:e is below the average, in terms of tish �rc�duetivity, relaiive t� si�nilar lakes, Fish in the lalce are fienerally not impacted. by the lake's turbidity (sus�ended solids and algae}, except in the sprin�„ At these tiines turbidity and hoat traf�c disturb spawning. Em�ironmental impaet of b�ating: Boating has the potential to scour bottom sediments , resuspend bottorn sediments, and destroy near-shc►rc ro�ted plants that protect shorelines from erosi�n. These impacts are most si�;nificant in shallow water (less than six feet or s�j. Tl�e potential impact of reducing the no-wal:e zone on lake quality is unclear, although morc bc�ats traveling cl�ser to the shore in shall.ow areds of'the lake; was censidered to be a negative factor in tenns of the ecologica.l health of the lake, Elow hag the qualtiy of the lake chan�ed over time: The MPCA has su�;�ested th�ti t�►e clariry of the lake has improved, on an annual basis. This improvement is less clear statistically when data fron� oniv the summer months are examine�i. Wced harvesting, herbicide application, and bnating seem to be signific:ant in reducing the amount of rooted weeds in the lake, hut do n�t improve algae �r turbidity prublems in the lake. The turbsdiry of the iake is hi�her that in other similar lakes. Internal a�id external loadinKs of' nutrients and seditncnt are a significant problem. Excessive boating may result in fewer rooted aquatic plants, but in and increase in al.gae and in turbidity. Turbidity is also dependent on the depth and sha}�e of the lake and on local w�ind conditions. The relative contributions o�'these factot's is difficult to quantify. Excessive wave action, from winds nr boats, are also responsible for shoreline erosion and a potential f'or an increase in lake turbidity.