In 2020 the USGS began a partnership with the U.S. Environmental Protection Agency (EPA) Region 1 Southeast New England Program for Coastal Watershed Restoration (SNEP) and EPA Office of Research and Development (ORD), Atlantic Coastal Sciences Division, Narragansett, RI in support of water-quality and ecological monitoring being conducted by ORD in the coastal waters around Wickford, RI. The USGS is conducting a study to characterize groundwater and surface water-quality to address the need for a better understanding of nutrient inputs to these coastal waters. The initial focus of the study is on local-scale hydrologic monitoring adjacent to Academy Cove.
Wickford, Rhode Island is in a densely developed area on the western shore of Narragansett Bay (fig. 1) where sewers are being installed to reduce nutrient loading (nitrogen is the constituent of greatest concern) to streams and coastal embayments. EPA ORD has been monitoring water-quality and sampling sediment and algae at ten locations in the saltwater embayments around Wickford since 2019; however, there is a lack of nitrogen loading information from the watershed to complement the embayment monitoring. Coastal areas receive nitrogen inputs from both groundwater and surface water sources in the watershed bordering the coastline. Nitrogen concentrations and loads to the Wickford embayments likely vary both spatially and temporally in response to seasonality, storm events, and longer-term factors such as changes in land-use and wastewater-disposal practices. Differences in travel times will also affect groundwater nitrogen loading from bordering watersheds.
Sewer installation has been ongoing since 2018 in Wickford, and, consequently, groundwater nitrogen loading to surface waters from local sources is expected to begin to decline over time. However, data are not available to determine current nitrogen-loading conditions or evaluate the magnitude and rate-of-change of loading in response to sewering. To better understand nutrient inputs to the coastal waters around Wickford, USGS is conducting a study to characterize groundwater and surface water-quality and loads. The initial focus of the study is on local-scale hydrologic monitoring near Academy Cove, including a detailed investigation of septic-system wastewater loading at the North Kingstown library which is located on the western side of the Cove (fig. 1). Groundwater nitrogen concentrations and loads before, during, and after the connection of the library septic system to the municipal sewer system will be evaluated to better understand and quantify changes in loading in response to sewering. An existing USGS groundwater model of the Hunt-Annaquatucket-Pettaquamscutt River Basins (https://pubs.er.usgs.gov/publication/sir20125114) is also being used to investigate groundwater nitrogen loading to streams and coastal waters at the more-regional watershed scale around Wickford Harbor.
Since 2021, several phases of field work have been conducted to characterize subsurface geologic conditions, groundwater flow directions, and groundwater and surface-water quality at the North Kingstown Free Library. A tide gage that measures water levels at 5-minute intervals was also installed in Academy Cove in 2021 (fig. 2). Site-characterization work completed in 2021 and 2022 includes installation of temporary sample points along the shoreline of Academy Cove (fig. 3), installation of wells and multilevel samplers (MLS), core collection, groundwater-level monitoring to determine local groundwater-flow directions, and collection of groundwater and surface-water samples.
The groundwater-monitoring network at the site consists of 8 MLSs and 9 water-table wells (fig. 4). MLSs contain multiple (typically 15) closely spaced sampling ports to provide detailed vertical profiles of groundwater quality. Vertical profiles of groundwater quality (nitrate, ammonium, dissolved oxygen, pH, and specific conductance) from an MLS sampled in September 2021 are shown in figure 5. Ongoing hydrologic data collection will provide information on current groundwater-quality conditions as well as changes in response to cessation of wastewater discharge from the library septic system.
Monitoring may be expanded spatially in future phases of the study to evaluate nitrogen loading to all of Academy Cove from the upgradient sources in the surrounding watershed. Over time, hydrologic and water-quality data will provide observations on the location, magnitude, and rates of change of nitrogen loading to the Cove in response to sewer connections and other nitrogen-management activities. These data will be used to support the models of estuarine response to nutrient loading being developed by EPA ORD.
- Overview
In 2020 the USGS began a partnership with the U.S. Environmental Protection Agency (EPA) Region 1 Southeast New England Program for Coastal Watershed Restoration (SNEP) and EPA Office of Research and Development (ORD), Atlantic Coastal Sciences Division, Narragansett, RI in support of water-quality and ecological monitoring being conducted by ORD in the coastal waters around Wickford, RI. The USGS is conducting a study to characterize groundwater and surface water-quality to address the need for a better understanding of nutrient inputs to these coastal waters. The initial focus of the study is on local-scale hydrologic monitoring adjacent to Academy Cove.
Sources/Usage: Public Domain.Figure 1. Map of the study area, Wickford, Rhode Island. (Public domain.) Wickford, Rhode Island is in a densely developed area on the western shore of Narragansett Bay (fig. 1) where sewers are being installed to reduce nutrient loading (nitrogen is the constituent of greatest concern) to streams and coastal embayments. EPA ORD has been monitoring water-quality and sampling sediment and algae at ten locations in the saltwater embayments around Wickford since 2019; however, there is a lack of nitrogen loading information from the watershed to complement the embayment monitoring. Coastal areas receive nitrogen inputs from both groundwater and surface water sources in the watershed bordering the coastline. Nitrogen concentrations and loads to the Wickford embayments likely vary both spatially and temporally in response to seasonality, storm events, and longer-term factors such as changes in land-use and wastewater-disposal practices. Differences in travel times will also affect groundwater nitrogen loading from bordering watersheds.
Sewer installation has been ongoing since 2018 in Wickford, and, consequently, groundwater nitrogen loading to surface waters from local sources is expected to begin to decline over time. However, data are not available to determine current nitrogen-loading conditions or evaluate the magnitude and rate-of-change of loading in response to sewering. To better understand nutrient inputs to the coastal waters around Wickford, USGS is conducting a study to characterize groundwater and surface water-quality and loads. The initial focus of the study is on local-scale hydrologic monitoring near Academy Cove, including a detailed investigation of septic-system wastewater loading at the North Kingstown library which is located on the western side of the Cove (fig. 1). Groundwater nitrogen concentrations and loads before, during, and after the connection of the library septic system to the municipal sewer system will be evaluated to better understand and quantify changes in loading in response to sewering. An existing USGS groundwater model of the Hunt-Annaquatucket-Pettaquamscutt River Basins (https://pubs.er.usgs.gov/publication/sir20125114) is also being used to investigate groundwater nitrogen loading to streams and coastal waters at the more-regional watershed scale around Wickford Harbor.
Since 2021, several phases of field work have been conducted to characterize subsurface geologic conditions, groundwater flow directions, and groundwater and surface-water quality at the North Kingstown Free Library. A tide gage that measures water levels at 5-minute intervals was also installed in Academy Cove in 2021 (fig. 2). Site-characterization work completed in 2021 and 2022 includes installation of temporary sample points along the shoreline of Academy Cove (fig. 3), installation of wells and multilevel samplers (MLS), core collection, groundwater-level monitoring to determine local groundwater-flow directions, and collection of groundwater and surface-water samples.
The groundwater-monitoring network at the site consists of 8 MLSs and 9 water-table wells (fig. 4). MLSs contain multiple (typically 15) closely spaced sampling ports to provide detailed vertical profiles of groundwater quality. Vertical profiles of groundwater quality (nitrate, ammonium, dissolved oxygen, pH, and specific conductance) from an MLS sampled in September 2021 are shown in figure 5. Ongoing hydrologic data collection will provide information on current groundwater-quality conditions as well as changes in response to cessation of wastewater discharge from the library septic system.
Sources/Usage: Public Domain.Figure 2. Tide gage installed in Academy Cove in 2021.
Sources/Usage: Public Domain.Figure 3. Groundwater sampling along the shoreline of Academy Cove, Wickford, Rhode Island, February 9, 2021.
Sources/Usage: Public Domain.Figure 4. Map showing the location of monitoring wells and multilevel samplers installed during two phases of drilling in 2021-22, Wickford, Rhode Island.
Sources/Usage: Public Domain.Figure 5. Vertical profiles of groundwater quality upgradient from Academy Cove, September 2021. Water-quality data are published in the U.S. Geological Survey National Water Information System (NWIS) database (https://waterdata.usgs.gov/nwis) Monitoring may be expanded spatially in future phases of the study to evaluate nitrogen loading to all of Academy Cove from the upgradient sources in the surrounding watershed. Over time, hydrologic and water-quality data will provide observations on the location, magnitude, and rates of change of nitrogen loading to the Cove in response to sewer connections and other nitrogen-management activities. These data will be used to support the models of estuarine response to nutrient loading being developed by EPA ORD.
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