2006 Results
In 2006 Rogers Lake had below average water quality compared to other lakes in this region (NCHF Ecoregion), receiving an overall D letter grade. This was substantially worse than the other three monitored years. The lake is eutrophic, but unlike many lakes with high nutrients did not have dense green algae blooms and had chlorophyll-a levels typical or only slightly worse than average. Rather, the water was brown, and sometimes strongly brown.
Trend Analysis
Four years of water quality monitoring have been conducted by the Anoka Conservation District (1998, 2000, 2003, 2006) and Secchi depths were taken by citizens one other year (1991). This is not enough data to perform a statistical test for a trend analysis. There is no trend apparent from superficial examination of the data.
Discussion
Rogers is a troubled lake system. It is surprising that such a small, isolated basin would have such high nutirent levels. The lakeshore is only partially developed, geese are not excessive (seen only once in 10 midday visits), and there are no streams flowing into the lake (i.e. small watershed). Pollutant sources are likely from within or adjacent to the lake. The organic lake sediments are one possible nutrient source, though the lake is too small for much wind mixing. It’s also possible that rough fish are contributing to poor water quality, but the fish community composition is unknown and no rough fish activity was seen by ACD staff. The water’s sewage odor on May 23 may be a clue that septic system failure(s) on lakeshore homes are occuring and impacting the lake, but this is uncertain. The saving grace of this lake is probably it’s aquatic plant community, albiet sparse and not very diverse, which is an essential ecological component for water quality. Plants reach the water’s surface on 20-40% of the lake. If the aquatic plant are lost, restoring good, ecologically healthy conditions are unlikely.
The LRRWMO and URRWMO should work together to address water quality problems in this lake. The first step of this process should be talking to lakeshore residents for their observations and thoughts. Thereafter, asessing the fish community, inspecting shoreland septic systems, and additional monitoring are may be revealing. Education, perhaps though on-site workshops, may be beneficial for homeowners and is recommended because on a small lake with such a small watershed each landowner’s actions could have large impacts on the lake. Education topics should include the value of aquatic plants (residents have done unauthorized vegetation clearing), lakeshore landscaping, lawn care, septic care, and any other topics requested by the residents.