Laserfiche WebLink
1. Oligotrophic - [TSI s 37] Clear, low productivity lakes with total phosphorus <br />concentrations less than or equal to 10 µg/L, Secchi disk <br />depths greater than or equal to 4.6 meters, and chlorophyll <br />a concentrations less than or equal to 2 ug/L. <br />2. Nlesotrophic - [38 s TSI s 50] Intermediate productivity lakes with total phosphorus <br />concentrations greater than 10 µg/L, but less than <br />25 µg/I,, Secchi disk depths from 4.6 meters to 2 meters, <br />and chlorophyll a concentrations between 2 ug/L and 7.5 <br />ug/L. <br />3. Eutrophic - [51 s TSI s 63] High productivity lakes generally having 25 to 60 µg2 <br />total phosphorus, Secchi disk depths from 2 meters to 0.85 <br />meters, and chlorophyll a concentrations between 7.5 ug/L <br />and 26 ug/L. <br />4. ~Iypereutrophic - [64 s TSI] Extremely productive lakes that are highly eutrophic, <br />disturbed and unstable (i.e., fluctuating in their water <br />quality on a daily and seasonal scale, producing gases, <br />off-flavor, and toxic substances, experiencing periodic <br />anoxia and fish kills, etc.) with total phosphorus <br />concentrations above 60 µg/L, Secchi disk depths less <br />than or equal to 0.85 meters, and chlorophyll a <br />concentrations more than 26 ug/L. <br />Determining the trophic status of a lake is an important step in diagnosing water quality problems. <br />Trophic status indicates the severity of a lake's algal growth problems and the degree of change <br />needed to meet its recreational goals. Additional information, however, is needed to determine the <br />cause of algal growth and a means of reducing it. <br />grass_lake_intro.doc Page 2 09/27/99 <br />