2002 Natural Resources Management

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averaged 3.3 feet between 1995 and 2000 (range of 2.2 feet to 4.4 feet). Further, the 1976 environmental assessment for the Hyman Freightway truck terminal (pg. 6 of report) suggested that the water quality of Langton Lake was "very close to the analysis of roadway runoff'. This is clearly not the case now and suggests that water quality in Langton Lake may have improved significantly from the 1970's and early 1980's. With the help of volunteer Dr. Jerry Beilby, a Langton Lake watershed resident and long -time user of the Park, monitoring of water levels in the middle cell in response to rainfall events between July and September 2001 was carried out. This type of data can be of help in assessing the suitability of a wetland or lake to support a stable emergent community along the edge of the water. Development of a stable, diverse emergent community is an important component of a healthy wetland /lake system. The data collected by Dr. Beilby is presented in Appendix A. Among the findings are that the water level "bounce" in Langton Pond was just over 6 inches (.5 feet) for a 2.5 inch, 24 hour rainfall (about a "1- year" rainfall). Further, it took several weeks for the water level to return to near the pre -event elevation (only one minor rainfall event was recorded during this period). Thus, the magnitude of the water level fluctuation in Langton Lake is moderate while the duration of the high water level is fairly long. For the most part, the system has sustained a moderately diverse and extensive emergent fringe, but preventing increases in both the bounce magnitude and duration will be important to protect the existing system. This means that expansions in the size of the watershed and in the impervious coverage (at least without extensive flow rate control) should be avoided. Aquatic Vegetation Survey As part of the field survey for Langton Lake conducted during this project, qualitative observations of submergent and emergent aquatic vegetation were made during field visits in June, July, and August 2001. The vegetation survey was carried out with two primary objectives in mid: 1. To determine to what extent, if any, there are infestations of exotic species. 2. To determine the diversity of native species in the lake. City of Roseville 43 Parks Natural Resource Management