2007 Results
In 2007 Typo Lake had extremely poor water quality compared to other lakes in this region (NCHF Ecoregion), receiving an overall F letter grade. This is the same letter grade as the previous ten years monitored, but 2007 was the worst of all. Average total phosphorus, chlorophyll-a, and Secchi transparency were the worst ever recorded and are so extreme that they may be the worst for a lake in Minnesota. A bright white Secchi disk could be seen only 3 to 8 inches below the surface. The reason for the especially poor conditions in 2007 seems to be drought-induced low water levels. The lake’s major inlet was monitored in 2007 and found to be similar to previous years or better. During drought it seems that internal loading (wind, rough fish, etc) builds nutrients and algae to very high levels because there is little flushing by storm water. Phosphorus and algae levels dropped by more than half when drought ended and ample rains fell in late August and September.
Trend Analysis
Eleven years of water quality monitoring have been conducted by the Minnesota Pollution Control Agency (1993, ’94, and ’95) and the Anoka Conservation District (1997-2001, 2003, 2005, 2007). Water quality has not significantly changed from 1993 to 2007 (repeated measures MANOVA with response variables TP, Cl-a, and Secchi depth, F2,8=3.74, p=0.07). Minnesota DNR fisheries data has anecdotal notes of severe algae blooms back to the earliest records in 1960. Locals familiar with the lake before 1960 indicate that the lake used to have better water quality, had aquatic plants including abundant wild rice, and was heavily used by waterfowl.
Discussion
Typo Lake, along with Martin Lake downstream, were the subject of an intensive TMDL study from 2001-03 by the Anoka Conservation District. This study documented the source of nutrients to the lake, the degree to which each is impacting the lake, and put forward lake rehabilitation strategies. Some factors impacting water quality on Typo Lake include rough fish, high phosphorus inputs from a ditched wetland west of the lake, and lake sediments. The study report was completed in early 2006, however it is still waiting for review and approval by the MPCA. In the meantime, the ACD and Sunrise River WMO are pursuing some lake improvement strategies recommended in the report.