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RESULTS <br />The qualify of most of the bays in Minnetonka was very good throughout the summer of <br />1998, (Figu'-es 1 to 4). The phosphorus and chlorophyll a concentrations of twelve of <br />the monitored bays were below the level which interferes with recreational use of lakes, <br />and the water clarity was above the level. Using the "Lake Qualify Report Card" scale <br />developed by Dick Osgood, (the scale uses the phosphorus and chlorophyll a <br />concentration and the Secchi disk depth), the bays would be given the following grades <br />In 1995,1996. and 1997: <br />SITE 1995 GRADE 1996 GRADE 1997 GRADE 1998 GRADE <br />Wayzata Bay <br />Lower Lake North <br />Lower Lake South <br />Lafayette Bay <br />Nortfi Arm <br />Crystal Bay <br />Ma)(well Bay <br />St. Albans Bay <br />West Upper Lake <br />Cooks Bay <br />West Arm <br />Jennings Bay <br />Halsted Bay <br />Browns Bay <br />Spring Park Bay <br />Stubbs Bay <br />Forest Lake <br />Harrisons Bay <br />A <br />A <br />A <br />A <br />A/B <br />A/B <br />A/B <br />A/B <br />B/A <br />B/C <br />C <br />C/D <br />D <br />A <br />A <br />A <br />A/B <br />B <br />B/A <br />B <br />A <br />A/B <br />B/A <br />C/D <br />C/D <br />D <br />A <br />.VB <br />A <br />A <br />B/A <br />A/B <br />C/B <br />A <br />A/B <br />B/C <br />C <br />D/C <br />D/C <br />A <br />B/A <br />C/B <br />C <br />C <br />A <br />A <br />A <br />A/B <br />B/A <br />A/B <br />C <br />A <br />B/A <br />B/A <br />C/D <br />C/D <br />D/C <br />A/B <br />A/B <br />C <br />D/C <br />C/D <br />As the Table shows, all bays either decreased in qualify from 1997, or remained the . <br />same. In general, the water quality decline was caused by an increase in the <br />chlorophyll a concentration, and a subsequent decrease In water clarity from 1997 <br />levels. There was very little change in the total phosphorus concentration in most bays <br />from 1997 to 1998. As was the case in 1996 and 1997, the total phosphorus grade for <br />most of the bays was lower than the Secchi disk and chlorophyll a grade. <br />Maxwell Bay has shown a consistent decline In water qualify since 1995, the first year <br />of this four year monitoring program. As the table shows, the bay declined from a <br />grade of A/B In 1995 to a grade of C in 1998. This decline may be due to water <br />entering Maxwell from the upstream Stubbs Bay, which has very poor water qualify. <br />This trend is of concern, since the same problems could occur in other high quality bays <br />like Crystal, Spring Park, and West Upper Lake, which are downstream of poor water <br />qualify bays.