News – Page 33 – Narrabay

Week of October 8 – 14, 2023

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on October 11th, 2023. Rainfall totaling 0.36 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.9 meters, compared to 2.2 meters on the previous survey (October 4th). The lowest clarity this week (2.2 meters) was measured at Phillipsdale, while the greatest clarity (3.4 meters) was measured at Edgewood Yacht Club and Bullock Reach. There was a general north-to-south gradient of increasing water clarity among the sites this week.

Week of October 1 – 7, 2023

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on October 4th, 2023. Rainfall totaling 1.27 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.2 meters, compared to 2.6 meters on the previous survey (September 27th). The lowest clarity this week (1.4 meters) was measured at India Point, while the greatest clarity (2.7 meters) was measured at Edgewood Yacht Club. There was no clear north-to-south gradient in water clarity among the sites this week.

Week of September 24 – 30, 2023

Water clarity was measured at six locations in the Providence River and Seekonk River estuaries on September 27th, 2023. Rainfall totaling 2.77 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.6 meters, compared to 2.5 meters on the previous survey (September 20th). The lowest clarity this week (2.2 meters) was measured at Phillipsdale Landing, Point Street Bridge, and India Point while the greatest clarity (3.0 meters) was measured at Edgewood Yacht Club. There was a general north-to-south gradient of increasing water clarity among the sites this week.

Week of September 17 – 23, 2023

Water clarity was measured at eight locations in the Providence River and Seekonk River estuaries on September 20th, 2023. Rainfall totaling 1.55 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.5 meters, compared to 1.4 meters on the previous survey (September 14). The lowest clarity this week (1.3 meters) was measured at India Point, while the greatest clarity (3.4 meters) was measured at Bullock Reach. There was a general north-to-south gradient of increasing water clarity among the sites this week.

Week of September 10 – 16, 2023

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on September 14th, 2023. Rainfall totaling 1.23 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 1.4 meters, compared to 2.2 meters on the previous survey (September 16th). The lowest clarity this week (0.9 meters) was measured at Phillipsdale Landing, while the greatest clarity (1.6 meters) was measured at Point Street Bridge, Bullock Reach and Conimicut Point. There was no clear north-to-south gradient in water clarity among the sites this week.

August 28-September3, 2023

On August 31^st, six stations were sampled for fecal coliform bacteria in the Providence River; one of these stations was also sampled for enterococci bacteria. There was a smaller set of stations sampled than normal due to weather conditions. Precipitation in the five days prior to sampling totaled 0.14 inches as recorded at TF Green.

Overall, bacteria counts were higher in the Providence River this week than during the previous sampling event on August 16. The fecal coliform geomean for the Providence River was 110 MPN/100 mL this week. The maximum count (430 MPN/100 mL) was measured at the Save the Bay site in the Providence River.

Enterococci was only sampled at one site this week. Gaspee Point measured a non-detect enterococci count.

The table below lists the Rhode Island bacteria standards for primary contact and shellfishing established by the Rhode Island Department of Environmental Management (RIDEM). RIDEM defines primary contact as any recreational activities in which there is prolonged and intimate contact with water, involving considerable risk of ingesting water (e.g., swimming, diving, water skiing and surfing). Please note that the RIDEM bacteria standards are provided here for informational purposes only and are not intended to indicate official state compliance with primary contact or shellfishing standards.

Summary of Rhode Island Bacteria Standards for Saltwater Primary Contact and Shellfishing

	Fecal Coliform	Enterococci
Primary Contact¹	Geometric mean ≤50 MPN/100 mL <10% of samples >400 MPN/100 mL	Geometric mean ≤35 colonies/100 mL All samples ≤104 colonies/100 mL²
Shellfishing	Geometric mean ≤14 MPN/100 mL <10% of samples >49 MPN/100 mL³	NO ENTEROCOCCI CRITERIA

¹Fecal coliform primary contact criteria applied only when adequate enterococci data are not available; ²Single sample maximum criterion for determining beach swimming advisories at designated beaches as evaluated by the Rhode Island Department of Health; ³For a three-tube decimal dilution

Table adapted from Rhode Island Water Quality Regulations (250-RICR-150-05-1); see regulations for complete details.

Week of September 3 – 9, 2023

Nutrient samples were collected from seven river stations and seven bay stations on September 6th, 2023. All bay stations were sampled at the surface and bottom. In the five days prior to sampling, there was no rainfall recorded at T.F. Green.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) concentrations were observed at Pawtuxet River @ Broad St (TN = 1,560 ppb, TDN = 1,510 ppb, DIN = 1,271.3 ppb). The lowest TN, TDN, and DIN were observed at Moshassuck River @ Higginson Ave. (TN = 539 ppb, TDN = 640 ppb, DIN = 483 ppb).

Among the bay stations sampled, the highest surface TN, TDN, and DIN concentrations were observed at Pawtuxet Cove (TN = 994 ppb, TDN = 799 ppb, DIN = 633.4). The lowest surface TN was observed at the Bullock Reach Buoy (TN = 438 ppb), the lowest surface TDN was observed at Pomham Rocks (TDN = 155 ppb), and lowest surface DIN was at Edgewood Yacht Club (DIN = 20 ppb). Chlorophyll a concentrations at the surface bay stations averaged 4.5 μg/L overall with a maximum of 7.9 μg/L at Conimicut Point.

Week of September 3 – 9, 2023

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on September 6th, 2023. There was no rainfall recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.2 meters, the same depth recorded on the previous survey (August 31st). The lowest clarity this week (1.5 meters) was measured at Phillipsdale Landing, while the greatest clarity (2.5 meters) was measured at Pomham Rocks. There was no clear north-to-south gradient in water clarity among the sites this week.

August 27-September 2, 2023

Surface chlorophyll data were collected on August 29, 2023 while the R/V Monitor was underway collecting nutrient samples in the Edgewood Shoals, Pawtuxet River and Southern Providence River areas (chlorophyll data were not collected for the Seekonk and Northern Providence River Channel areas due to data logging issues). The average chlorophyll concentrations were categorized fair in the areas surveyed. Overall, chlorophyll ranged from 5.57 µg/L to 12.80 µg/L with an average of 10.46 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

Week of August 27 – September 2, 2023

Water clarity was measured at one location in the Providence River estuary on August 31st, 2023 due to extreme conditions. Edgewood Yachet Club had a measured clarity depth of 2.2 meters. Rainfall totaling 0.14 inches was recorded at TF Green in the five days prior to the survey. Secchi depth increased by 0.2 meters, compared to previous survey on August 23rd.