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At this point the Minnesota Pollution Control Agency, joined with the newly <br />organized Lake Minnetonka Conservation District to commission a study of lake <br />pollution. Entitled "A Program for Preserving the Quality of Lake Minnetonka", the <br />"Harza Study" (as it will be referred to hereafter) found that this nutrient input, <br />particularly phosphorus, was being generated from two principal sources: the seven <br />municipal sewage treatment plants; and urban stormwater runoff coming from within <br />the watershed. <br />The first pollution source, nutrient rich effluent outflowing from the municipal <br />sewage treatment plants, was systematically eliminated during the late 1 970's and <br />early 1 980's by multi-million dollar construction of sewer interceptors designed to <br />remove effluent from the watershed. But stormwater runoff is a different matter. <br />Unlike point-source sewage pollution, there is no economically practical way to <br />artificially collect or treat non-point source stormwater pollution. <br />Lake Minnetonka is fed by neither spring nor tributary ’. The sole replenishment <br />comes from storm w ater runoff from the w atershed, of which over one-third flows <br />from or through Orono. Lake Minnetonka, second only to Lake Michigan in this <br />region, has an extremely long 25-year flush-out period. This means that careful and <br />continuous attention must be given to the quality of runoff into the Lake. The <br />various studies conducted in the 1960's and 1970's recommended that lakeshore <br />density ue limited and that the natural system of wetlands and marshes be <br />forever protected and prescr>ed as the only practical, economic method of <br />filtering nutrients from storm water runoff. <br />Implementation of density limitations relies on breaking the "Urbanization Spiral", <br />the development paradox that results from providing urban-level municipal services <br />for new development. The paradox is that if municipal ser\ ices are extended to to <br />rural zones, the cost of these services ta.\es the land to the point that higher density <br />development is required. Particularly in the case of sewers, even if extended to <br />existing pockets of development "to solve a pollution problem", inflation, topography <br />and and sparse settlement combine to sen costs skyrocketing. Such costs can only <br />be paid by increasing development densities, which in turn cause increasing levels <br />of storm water nutrient pollution. This spiral results in even gieater levels of <br />pollution than the original sewage 'problem' might have been. For example, Eugene <br />Hickock's 1973 Storm Water Impact Statement for the Metropolitan Council <br />identified up to 10 times more phosphorus alone from urban storm water runotT than <br />from Orono's low-densitv rural land use.