Water Quality Sampling and Monitoring of the Pawcatuck River Watershed

Science Center Objects

The Pawcatuck River and the Pawcatuck River Estuary and Little Narragansett Bay form part of the boundary between the States of Connecticut and Rhode Island. Both states have identified water quality impairments within these waters related to nutrients (insufficient oxygen) and bacteria. Studies of the eutrophication potential of Long Island Sound embayments have identified that the Pawcatuck River Estuary has the highest total load of nitrogen per embayment area of all embayments studied throughout Long Island Sound.

 

Continuous water quality monitor that is deployed off a bridge in Westerly RI, just upstream of the gage.

Continuous water quality monitor that is deployed off a bridge in Westerly RI, just upstream of the gage.

(Credit: Jonathan Morrison, US Geological Survey, New England WSC. Public domain.)

From May 2019 to May 2020, USGS will collect water quality samples for the Connecticut Department of Energy and Environmental Protection (CTDEEP) and the Rhode Island Department of Environmental Management (RIDEM) in the freshwater Pawcatuck River. The data collected through this project is intended to be used by the states of CT and RI to support a HSPF watershed loading model for the Pawcatuck River watershed to quantify loads to the Pawcatuck River Estuary. It is planned that future steps by CTDEEP and RIDEM will use this loading information in an estuarine water quality model to determine target nitrogen loads. The data will be used to inform development of management activities to address nutrient-related water quality impacts.

Objectives:

  • Establish a monitoring network to collect samples from fourteen locations in the Pawcatuck River watershed for analysis of nutrients and related parameters as well as stream discharge.
  • Collect continuous water quality data at the end of the non-tidal portion of the Pawcatuck River watershed.

 

List of analytes, Analysis Methods and parameter codes
Analyte Lab Analysis method Parameter Codes NWQL Minimum Reporting Limit
Ammonia NWQL Method ID: I-2522-90 (Fishman, 1993) 608 0.01 mg/L
Ammonia + Organic Nitrogen (Whole) NWQL Method ID: I-4515-91 (Patton and Truitt, 2000) 625 0.07 mg/L
Ammonia + Organic Nitrogen (Dissolved) NWQL Method ID: I-2515-91 (Patton and Truitt, 2000) 623 0.07 mg/L
Nitrite NWQL Method ID: I-2540-90, I-2542-89 (Fishman, 1993) 613 0.001 mg/L
Nitrite + Nitrate NWQL Method ID: I-2547-11  (Patton and Kryskalla, 2011) 631 0.04 mg/L
Phosphorus ( Dissolved ) NWQL Method ID: 365.1 (EPA 365.1, 1993) 666 0.003 mg/L
Orthophosphate NWQL Method ID: I-2601-90, I-2606-89 (Fishman, 1993) 671 0.004 mg/L
Phosphorus (Whole) NWQL Method ID: 365.1 (EPA 365.1, 1993) 665 0.004 mg/L
Total nitrogen (NH3+NO2+NO3+Organic) NWQL Method ID: I-2650-03 (Patton and Kryskalla, 2003) 62854 0.05 mg/L
Total Particulate Nitrogen (TPN) NWQL Method ID: 365.1  (Zimmerman and others, 1997) 49570 0.03 mg/L
Chlorophyll-a, phytoplankton NWQL Method ID: 445.0 (Arar and Collins, 1997) 70953 0.1 ug/L
Pheophytin, phytoplankton NWQL Method ID: 445.0 (Arar and Collins, 1997) 62360 0.1 ug/L
Total Suspended Solids, Residue on Evaporation (ROE) NWQL Method ID:  I-3765-85 (Fishman and Friedman, 1989). Page 443 530 15 mg/L
Chlorophyll Field Bennett and others (2014), YSI EXO user Manual (appendix 10) N/A N/A
Dissolved Oxygen Field Wagner and others (2006) 300 N/A
Specific conductance Field Wagner and others (2006) 95 N/A
pH Field Wagner and others (2006) 400 N/A
Water Temperature ℃ Field Wagner and others (2006) 10 N/A
Turbidity Field Wagner and others (2006) 63680 N/A