2002 Natural Resources Management

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Langton Lake has benefited tremendously from concerted efforts by local residents and the City for its protection. Two efforts that stand out are the successful intervention to prevent filling of the southern part of the Lake in the 1970's, and the construction of a detention basin to treat runoff from much of the new industrial and commercial developments to the south of the lake. The desire to protect Langton Lake was also in large part responsible for passage of a shoreland zoning ordinance by the City in 1974, making Roseville the first city in the state to take such action. Technical Findings Due to a lack of available data for water quality in Langton, the City initiated a limited sampling effort for selected water quality parameters. The sampling was undertaken during the 2001 growing season on June 7th, July 17th and August 23rd. Water Quality Water clarity, measured by secchi depth, often indicates a lake's overall water quality, especially the amount of algae present. Growing season secchi depth for Langton averaged around 2.5 feet in 2001 (Appendix A, Table 1). Generally, sunlight of adequate intensity to support rooted plant growth can penetrate a lake water column to 1.5 -2 times lake secchi depth. This explains to a large extent why almost all of Langton Lake supports lush submergent vegetation since the maximum depth of the Lake, at 5 feet, is only about twice the water clarity reading. The seasonal mean concentration for total phosphorus in Langton is 80 ug /l (ppb) (Appendix A, Table 1). This puts Langton Lake in category D, described in the Metro Lake water quality report card as "poor quality with recreational use severely impaired." It is encouraging however, to note that it is close enough to the upper limit of 69 ug /l in category C (average quality; moderate impairment for recreational use, often in the later half of summer) to make it an achievable goal for the future. There is little historical water quality data for Langton Lake available in the state's water quality database. The Minnesota Pollution Control Agency's (MPCA) lake water quality database indicates that the summer mean water quality reading for the south bay was 1.6 feet in 1984 and City of Roseville 42 Parks Natural Resource Management