Embayment Monitoring to Support Nutrient Management Activities in Connecticut for the Long Island Sound

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The USGS, in cooperation with the CT Department of Energy and Environmental Protection (CTDEEP) will be collecting water quality and hydrologic data at four embayments: Mystic, Norwalk, Saugatuck, and Sasco-Saugatuck complex from April 2021 to March 2024.

Continuous water quality station on the Mystic River at the Mystic Seaport, Mystic CT

Continuous water quality station on the Mystic River at the Mystic Seaport, Mystic CT (Site ID 412141071580200). (Credit: Paul Solis, U.S. Geological Survey. Public domain.)

The state of Connecticut continues to promote a comprehensive approach to managing the impacts of nutrients to Long Island Sound and it’s coastal embayments. The U. S. Geological Survey (USGS), in cooperation with the Connecticut Department of Energy and Environmental Protection will be collecting water quality and hydrologic data at four embayments across Long Island Sound: Mystic, Norwalk, Saugatuck, and Sasco-Saugatuck complex. Data will be collected in the identified embayments for a duration of two years. Data collection began in the Mystic and Norwalk in May 2021 and data collection will begin in the Saugatuck and Sasco/Southport Harbor starting in April 2022. Discrete water-quality samples are planned to be collected at near surface and near bottom at multiple locations at various tidal cycles in each embayment. Discrete samples will be analyzed for nutrients, carbon, total suspended solids, silica, alkalinity, biological oxygen demand, and chlorophyll a. Selected sites will also have continuous water-quality monitoring at near surfaces and near bottom for water temperature, specific conductance, salinity, dissolved oxygen, turbidity, and chlorophyll a. USGS will also collect hydrologic data such as velocity and stage at selected locations in each embayment.

Continuous stage only gaging station located at Mystic River at Rt. 1 bridge, CT

Continuous stage only gaging station located at Mystic River at Rt. 1 bridge, CT (USGS Site ID 412117071580800). (Credit: Patrick McNamara, U.S. Geological Survey. Public domain.)

The objectives of the project are to 1) Obtain representative water-quality data under a range of seasonal conditions to characterize the water quality spatially and vertically in each embayment. 2) Monitor selected water-quality parameters with high temporal resolution to provide time-series data needed for water quality model calibration and evaluation 3) Monitor selected physical water-quality parameters at multiple locations in each embayment that will provide understanding of variability at spatial scales. This effort will develop a series models from priority embayments that will improve the understanding of physical and chemical processes of embayments in Long Island Sound.

 

Continuous water quality gaging station located at Norwalk River at Norwalk Aquarium near South Norwalk, Connecticut

Continuous water quality station located on the Norwalk River at Norwalk Aquarium near South Norwalk, CT (USGS site ID 410606073245700). (Credit: Paul Solis, U.S. Geological Survey. Public domain.)

Installation of continuous water quality gaging station at Mystic River at RAM Island Yacht Club at Noank, Connecticut

Installation of continuous water quality station on the Mystic River at RAM Island Yacht Club at Noank, CT (USGS site ID 411940071590300). (Credit: Paul Solis, U.S. Geological Survey. Public domain.)

 

Map of Norwalk Embayment Monitoring Sites

Map of Norwalk embayment monitoring sites.

Map of Mystic Embayment Monitoring Sites

Map of Mystic embayment monitoring sites.

List of analytes being collected

Analyte Parameter Codes Minimum Reporting Limit
Ammonia in seawater (Dissolved) 00608 0.01 mg/L
Ammonia + Organic Nitrogen (Whole) 00625 0.14 mg/L
Nitrite + Nitrate 00631 0.04 mg/L
Orthophosphate 00671 0.008 mg/L
Phosphorus in brines (Whole) 00665 0.008 mg/L
Chlorophyll-a, phytoplankton 70953 0.1 ug/L
Pheophytin, phytoplankton 62360 0.1 ug/L
Silica in seawater (Dissolved) 00955 0.12 mg/L
Alkalinity 39086 8.0
Dissolved Organic Carbon (DOC) 00681 0.6 mg/L
Total Suspended Solids (TSS) 00530 2 mg/L
Carbonaceous Biological Oxygen Demand (CBOD)  80082 2 mg/L
Chlorophyll-a 00925 N/A
Dissolved Oxygen 00300 N/A
Specific conductance 00095 N/A
Water Temperature ℃ 00010 N/A
Turbidity 63680 N/A
Barometric pressure 00025 N/A
Underwater Photosynthetically Active Radiation (PAR) 99997 N/A