3.1 Water Quality
- The water quality in Langdon Lake
since 1998 has consistently been scored in the D-F grade range on the
District’s annual lake report cards.
The mean summer 2004 total phosphorus concentration was 138 μg/L,
well in excess of the District’s 55-70 μg/L interim goal. Based on this monitoring history, Langdon Lake’s water quality is not
supportive of swimming.
- During development of the HHPLS the
subwatershed was under the review of two Regional Teams, which recommended
different goals for the lake: 55 μg/L and 70 μg/L. The state standard, and thus the
long-term goal for Langdon
Lake is 40
μg/L. Phosphorus loading
reductions would be necessary to achieve any of these desired in-lake
phosphorus concentrations. The
HHPLS and modeling performed for this plan also noted that internal
loading and possibly phosphorus export from wetlands in the subwatershed
were likely significant sources of excess phosphorus in the lake.
- Runoff from developed areas in the
eastern subwatershed receives little if any treatment prior to discharge
to receiving waters.
- No monitoring data are available for Saunders Lake
or Black Lake.
- Development, redevelopment, and
reconstruction in the subwatershed are predicted to increase nutrient and
TSS loads from the watershed as well as increasing the volume of
stormwater runoff, potentially further degrading water quality in Langdon Lake and streams and wetlands in