2017 Water Quality Results Reported

CONCLUSIONS FROM THE REPORT

“The 2017 water quality data from Mohawk Island, Pot Island, and Three Island indicate that the lake represents ideal water quality conditions in comparison with NH state water quality standards and thresholds. Lake Winnisquam sup-ports an oligotrophic lake classification as phosphorus and chlorophyll-a levels are consistently below the oligotrophic thresholds, and water clarity and dissolved oxygen levels are high. The decreasing (improving) phosphorus trend sug-gests that nutrient loading into the lake (from fertilizers, pesticides, agricultural runoff, septic failure, etc.) has been decreasing throughout the watershed over time. Apparent color measured in the epilimnion indicates that the overall lake color is clear with little dissolved organic matter that imparts a tea color to the water. Turbidity is consistently low (good) suggesting minimal suspended solids and particulate matter. This is further supported by the high water clarity (transparency). Conductivity levels are slightly elevated and higher than the state median of 40.0 uS/cm and have sig-nificantly increased (worsened) over time. Chloride levels are between 10 and 20 mg/L, which is above the NH state median of 4 mg/L, but well below the NH state chronic chloride standard of 230 mg/L. The increasing conductivity lev-els are most likely a result of road salt usage on impervious surfaces that enters the lake through stormwater runoff and groundwater discharge. Lake pH levels are generally within an ideal range for aquatic life. The ANC level indicates that the lake is moderately vulnerable to changes in pH from acid rain and other pollutants. Best management practic-es for road salting, development, and stormwater should be implemented throughout the watershed as increased fre-quency and intensity of precipitation events will continue to impact water quality. Refer to “Ready, Set, Action” on the next page for collaborative watershed management considerations that can be executed to effectively protect lake water quality health.”

READ FULL REPORT

Lake Winnisquam Report-Final

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