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The relatively low water quality grades for Bennett and Langton lakes are not unusuai in an <br />urban en�ironment. Shallow Iakes (i.e., those with mean depths of iess than 10 feet) like Bennctt <br />Lake and Langton Lake are extremely productive envrronments, ineaning that even under <br />pristine conditions they are rich in aquatic vegetation. The main reason for this is sunlight can <br />penetrate to the bottom almost anywhere in the lake at adequate intensities to support both <br />vegetation rooted to the lake sedi�nents well as other typcs of plants like algae that float in the <br />water column. In addition, nutrients washed into the lake from the surrounding watershed — <br />whether heid in the lake sediments or suspended in the water column — are available to support <br />plant growth. In contrast, deeper lakes often have a signi�cant portion of the lake bottom that <br />docs not receive enough sunlight to support plant growth. Also, the deep portion of a la�Ce is <br />separated from the upper shallow portions af a lake for much of the growing season through a <br />process known as thermal "stratzfication". With the warmer water layer on top and cooler Iayer <br />on the bottozn, relatively little water is exchanged between the two iayers for most of the <br />recreation season. The deeper portion of these types of lakes can act as "storage" for excess <br />nutrients, holding high concentrations in areas of the lake that are too deep to allow the light <br />intensities necessary to support algae growth. <br />Each of the two lakes is descr�bed in detail below in terms of its basin and watershed <br />characteristics as weIl as its ecology, use and quality. <br />LANGTON LAKE <br />Lake and Wafershed 4�er�iew <br />Figuze 5.1 shows the location of Langton Lake and the approximate bounds of its waters�ed. <br />Langton Lake occupies a total surface area of 23 acres. Average depth of the lake is around 3 <br />feet, while the rnaximum depth is around 5 feet. <br />The watershed for Lan�ton Lake is approximately 212 acres and is roughly bounded on the east <br />by Fairview Avenue, the wcst by Cleveland Avenue, the north by County Road D and the south <br />by County Road C. Residential and commercial/industrial land use comgrises <br />City of Roseville 36 <br />Parks Natcual Resocirce Maiingement <br />