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APPENDIX F <br /> <br /> <br /> <br /> <br />City of Arden Hills <br />WSB Project No. 3455-200 <br /> <br />Lakes and Ponds <br />The Minnesota Pollution Control Agency (MPCA) and Minnesota Department of Natural <br />Resources (MDNR) maintain lake information databases on many lakes in Minnesota. The <br />data is available on the web at http://www.pca.state.mn.us/water/lakequality.html and <br />www.dnr.state.mn.us/lakefind.html. <br /> <br />Summary water quality data is available for all the lakes in Arden Hills except Sunfish Lake (no data) on <br />the TCAAP property. This lake has the potential to be studied and monitored as part of the redevelopment <br />of TCAAP. Table 5-1 provides summary data on the each of the lakes in Arden Hills. <br /> <br />Trophic State Index (TSI) combines measures of summer Secchi Disk transparency and epilimnetic <br />(upper portion of lake characterized by warmer and lighter water) concentrations of chlorophyll-a and <br />total phosphorus to come up with the value. The index ranges from 0 to 100, with the higher values <br />indicating more eutrophic (over nourished) conditions in the lake. For the ecoregion Arden Hills is <br />located in, typically a TSI value of less than 59 fully supports swimming. Swimming is partially <br />supported between a TSI value of 60 and 65. <br /> <br />Josephine and Round lakes both fully support swimmable use classification, according to their TSI, <br />although they are sensitive to increases in phosphorus nutrient loading. However, there is no access to <br />Round Lake for swimming use. Lake Johanna only partially supports swimmable use classification due to <br />algae blooms and low transparency for a significant portion of the summer. Karth, Little Lake Johanna <br />and Valentine lakes do not support swimmable use classification due to severe and frequent algae blooms <br />and low transparency for most of the summer. Round, Karth, Little Lake Johanna and Valentine lakes <br />have either small surface areas or are quite shallow in average depth and therefore would not be <br />considered likely candidates for swimmable use. However, water quality data in support or non-support of <br />this use is important for wildlife management of these water bodies. <br /> <br />Lake Josephine Assessment Report <br />The MPCA along with MDNR, Ramsey County Public Works, RCWD and Josephine Lake Association <br />issued a Lake Assessment Report for Josephine Lake in 1998. Pertinent portions from that report are as <br />follows: <br /> <br />(page iii) <br /> <br />A good historical data base is available for assessing trends in water quality of Lake Josephine. These <br />data include 22 years of Secchi data and several years of water chemistry data. Based on an analysis of 22 <br />years of CLMP, MPCA, DNR, Met. Council, Ramsey County, and two environmental consulting firm's <br />Secchi transparency data, Lake Josephine exhibited a significant improvement in transparency over time <br />(RK = 0.52; p=0.0008). Summer mean Secchi transparency measures ranged from 2.3 to 4.3 feet from <br />1975-1979. In contrast, from 1981-1989 summer-mean Secchi ranged from 3.0 to 10.2 feet and from <br />1990-1998 summer-mean Secchi ranged from 5.2 to 12.1 feet. Summer-mean total phosphorus and <br />chlorophyll-a concentrations exhibited a decline over this time period as well. <br /> <br />(page 3) <br /> <br />Lake Josephine's watershed is relatively small at about 734 acres, excluding the lake. The vast majority <br />(96%) of the watershed is in urban/residential lake use. This percentage, although not typical for lakes in <br />the North Central Hardwood Forest ecoregion, is rather typical for lakes in the Twin Cities metro area. <br />Dr <br />a <br />f <br />t <br /> <br />11 <br />/ <br />2 <br />0 <br />/ <br />2 <br />0 <br />1 <br />7