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<br />I <br />I <br />, <br />I <br />I <br />I <br />I <br />I <br />I <br />II <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />, <br />I <br /> <br />9.7.01 <br /> <br />Water Quality Analyses <br /> <br />P-8 models were created for the proposed regional ponds. The ponds were <br />designed to meet NURP (Nationwide Urban Runoff Program) standards, <br />which are removal of 90% of total suspended solids (TSS) and 65% of total <br />phosphorus (TP). As with the hydrologic modeling, no upstream drainage <br />areas were used in the water quality modeling. The ponds were modeled <br />using only the immediate drainage areas. Therefore, it is recommended to <br />model the entire drainage system during either a feasibility study or final <br />design to calculate the pollutant removal efficiencies of the entire system. The <br />results from the P-8 models can be found in Appendix D. <br /> <br />Lakes and Ponds <br /> <br />The Minnesota Pollution Control Agency (MPCA) and Minnesota Department <br />of Natural Resources (MDNR) maintain lake information databases on many <br />lakes in Minnesota. The data i~ available on the WEB at <br />htm: Ilwww.nca.state.mn.uslwateTllakeunalitv.html and www.dnT.statemn.us/lakefind.html. <br />Summary water quality data is available for all the lakes in Arden Hills except <br />SunfIsh Lake (no data) on the TCAAP property. This lake has the potential to <br />be studied and monitored as part of the redevelopment of TCAAP. The <br />information from the MPCA's database, as of August 2001, can be found in <br />Appendix E. Table 4 provides summary data on the each of the lakes in <br />Arden Hills. <br /> <br />Table 4 <br /> <br />Summary Data on Lakes in Arden Hills <br /> <br /> Trophic <br />Lake Name MDNR Surface State Recreational <br />Number Area Index Suitability <br /> (TSI) <br />Josephine 62 - 57 109 acres 51 Full Support (M) <br />Round 62 - 70 122 acres 54 Full Support (M) <br />Valentine 62-71 60 acres 65 Non-Supported <br />Karth 62 - 72 15 acres 66 Non-Supported <br />Johanna 62 - 78 230 acres 54 Partial Support <br />Little Lake Johanna 62 - 58 18 acres 85 Non-Supported <br /> <br />Trophic State Index (TSI) combines measures of summer Secchi Disk <br />transparency and epilimnetic (upper portion of lake characterized by warmer <br />and lighter water) concentrations of chlorophyll-a and total phosphorus to <br />come up with the value. The index ranges from 0 to 100, with the higher <br />values indicating more eutrophic (over nourished) conditions in the lake. For <br />the ecoregion Arden Hills is located in, typically a TSI value of less then 59 <br />fully supports swimming. Swimming is partially supported between a TSI <br />value of 60 and 65, <br /> <br />City of Arden Hilis, Minnesota <br />Local Stormwater Management Plan <br /> <br />A-ARDEN0101.00 <br />Page 26 <br />