Water Quality Monitoring

Lake Pocotopaug

Beginning in 2014, NEAR was selected to perform an intensive review of all past lake loading models and water quality data studies previously conducted at Lake Pocotopaug, CT. Lake Pocotopaug is plagued by persistent seasonal cyanobacteria blooms that were not remedied by either of the alum treatments performed in 2000-2001. NEAR evaluated the increase in volume of anoxic water since 1995 as well as the persistence of anoxia later into the season from 1995-2017. Statistical analysis revealed that cyanobacteria populations are stimulated by relatively low phosphorus concentrations and very high nitrogen concentrations, which is a combination of internal ammonia generation and external stormwater inputs. Hydrologic data also indicates that cyanobacteria increases coincide with lake stagnation and severely reduced summer flushing.

Internal Loading & Cyanobacteria Bloom Mitigation at Bolton Lake

NEAR was called upon to evaluate the causes of a cyanobacteria bloom at Lower Bolton Lake in eastern Connecticut. NEAR’s work compelled the CT DEEP/DPH to publish guidance on harmful cyanobacteria blooms in recreational waters in 2013. NEAR conducts stormwater monitoring and works in concert with the Towns of Bolton, Vernon, and Coventry, as well as the CT DEEP and multiple homeowner associations. NEAR is also responsible for ongoing aquatic plant management, as all three Upper, Middle, and Lower Bolton Lakes have aquatic invasive species requiring ongoing attention.

Watershed Evaluations

West Hill Pond

From 2015-2018, NEAR conducted a detailed analysis of historic and updated water quality data for West Hill Pond (261-acres) in New Hartford, CT. Sampling included monthly water quality sampling from two lake stations, all tributaries, and the outlet dam culverts. NEAR exampled the results of two stormwater sampling events and also conducted two extensive lakeshore seepage surveys, during both “Dry” and “Storm” conditions. The perimeter seepage surveys were organized to coincide with a required 6ft drawdown in order to repair the lake’s dam. During this survey, NEAR identified locations of groundwater inputs and septic system impairment. This data was used to create a long-term monitoring and management plan for West Hill Pond, which is the last publicly accessible oligotrophic lake in the state of CT. NEAR continues to work for the West Hill Pond Association and has since helped them establish a resident monthly water quality monitoring program. All data was compiled into various nutrient loading models including LLRM.

Lake Pocotopaug EPA 9-Element Watershed Based Plan

NEAR was selected by the Town of East Hampton to conduct a detailed assessment of the Lake Pocotopaug watershed. This assessment included mapping all roadway stormwater culverts in the watershed, as well as outfall sampling during “Dry” and “Storm” conditions in 2014-2016. Updated watershed information was combined with the previous loading assessments to identify specific watershed improvement projects.

The Watershed-Based Plan was approved by the State of CT and the EPA, and the Town was then granted a Clean Water Act Section 319 grant for implementation of low impact development projects aimed at reducing overland flow and nutrient concentrations in stormwater. NEAR understands that not all LID/BMP work is created equal and that maintenance and follow-up sampling is required to ensure long-term nutrient mitigation in stormwater management.

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