News – Page 3 – Narrabay

September 30, 2026

Surface chlorophyll data were collected on September 30, 2026, while the R/V Data Stream was underway collecting nutrients samples in the Providence and Seekonk River Estuaries. The average chlorophyll concentrations were categorized as good overall with all areas sampled having average chlorophyll concentrations <5 µg/L. Overall, chlorophyll ranged from 1.23 µg/L to 12.56 µg/L with an average of 2.58 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

August 19, 2026

Phytoplankton samples were collected on August 19, 2026 at Bullock’s Reach and analyzed in the laboratory shortly after collection.

The water temperature was 24.59 °C, the salinity was 24.02 psu, and the chlorophyll a was 6.27 ug/L.

The qualitative tow net sample had a moderate filtration time. The filtrate was mostly clear with some large pieces of algae.

The analysis of the quantitative whole water sample revealed a total of 353,000 cells/L. The microflagellates were found at 240,000 cells/L. The most predominant phytoplankton genera were Prorocentrum spp. at 29,000 cells/L, Protoperidinium spp. at 14,000 cells/L, and Pennate Unknown spp. at 14,000 cells/L.

200x phase contrast image of Polykrikos spp.

Polykrikos spp. are unarmored dinoflagellates found in tropical to temperate marine waters. They often feed on diatoms as well as other dinoflagellates such as Ceratium and Gonyaulax. Their predation of Alexandrium species can contribute to the reduction of toxic algal blooms.

September 22, 2026

On September 22^nd, 2026 twenty stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers; five of these stations were also sampled for enterococci bacteria. In the five days prior to sampling, 0.27 inches of precipitation was recorded at TF Green.

Fecal coliform counts were higher in the Seekonk River, compared to the Providence River (geometric mean of 67 MPN/100 mL for the Seekonk River compared to 12 MPN/100mL for the Providence River) for sampling conducted on September 22nd. The maximum count (1,500 MPN/100 mL) was measured at the Point St. Bridge sampling location.

Enterococci results had an overall geometric mean of 33 MPN/100 mL. Enterococci counts ranged from <10 MPN/100 mL at most sites to 496 MPN/100 mL at Point St. Bridge.

The next scheduled sampling date is October 7^th.

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.

September 22, 2026

Surface chlorophyll data were collected on September 22, 2026, while the R/V Data Stream was underway collecting bacteria samples in the Providence and Seekonk River Estuaries. The average chlorophyll concentrations were categorized as good in the Northern Providence River Channel and the Pawtuxet River Area, and as fair in all other areas. The average chlorophyll concentrations were categorized as fair over all areas surveyed. Overall, chlorophyll ranged from 2.10 µg/L to 15.02 µg/L with an average of 6.57 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

September 22, 2026

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on September 22, 2026. In the five days prior to the survey, 0.27 inches of precipitation were recorded at TF Green. Secchi depth averaged 3.5 meters. The lowest clarity this week (2.7 meters) was measured at Phillipsdale Landing, while the greatest clarity (3.9 meters) was observed at Conimicut Point. There was no clear north-to-south gradient in water clarity among the sites this week. Overall, water clarity increased from the previous measurements (data collected September 16, 2026).

September 16, 2026

Surface chlorophyll data were collected on September 16, 2026, while the R/V Data Stream was underway collecting nutrients samples in the Providence and Seekonk River Estuaries. The average chlorophyll concentrations were categorized as fair overall with all areas sampled having average chlorophyll concentrations between 5 µg/L and 20 µg/L. Overall, chlorophyll ranged from 3.77 µg/L to 20.37 µg/L with an average of 8.27 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

September 16, 2026

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on September 16, 2026. In the five days prior to the survey, 4.18 inches of precipitation were recorded at TF Green. Secchi depth averaged 2.7 meters. The lowest clarity this week (1.5 meters) was measured at Phillipsdale Landing, while the greatest clarity (3.7 meters) was observed at Conimicut Point. There was a general north-to-south trend of increasing water clarity among the sites this week. Overall, water clarity decreased from the previous measurements (data collected September 9, 2026).

September 16, 2026

Water column profiles were conducted using a Seabird Electronics profiler at six locations in the Providence River and one location in the Seekonk River on September 16, 2026. In the five days leading up to this, there were 4.18 inches of rain recorded at T.F. Green International Airport (Warwick, RI). The water column was weakly stratified at Bullock Reach, Conimicut Point, Edgewood Yacht Club and Pomham Rocks. Moderate stratification was observed at India Point Park and Phillipsdale Landing. The water column at Pawtuxet Cove was strongly stratified.

Dissolved oxygen conditions below the hypoxia threshold (2.9 mg/L) were observed in the lower part of the water column at Edgewood Yacht Club, India Point Park and Phillipsdale Landing. The highest fluorescence reading was observed one meter below the surface at Phillipsdale Landing.

September 9, 2026

Water column profiles were conducted using a Seabird Electronics profiler at seven locations in the Providence River and one location in the Seekonk River on September 9, 2026. In the five days leading up to this, there were 0.06 inches of rain recorded at T.F. Green International Airport (Warwick, RI). The water column was weakly stratified at Phillipsdale Landing and well-mixed at all other profiling locations: Bullock reach, Conimicut Point, Edgewood Yacht Club, Pawtuxet Cove, Pomham Rocks, Point Street Bridge and India Point Park.

Dissolved oxygen conditions below the hypoxia threshold (2.9 mg/L) were observed in the lower part of the water column at Pawtuxet Cove, Pomham Rocks and Point Street Bridge. The entire water column at India Point Park and Phillipsdale Landing had dissolved oxygen concentrations below the hypoxia threshold. The highest fluorescence reading was observed 1.25 meters below the surface at Phillipsdale Landing.

September 2, 2026

Water column profiles were conducted using a Seabird Electronics profiler at seven locations in the Providence River and one location in the Seekonk River on September 2, 2026. In the five days leading up to this, there were 1.25 inches of rain recorded at T.F. Green International Airport (Warwick, RI). The water column was weakly stratified at every profiling location: Bullock Reach, Conimicut Point, Pawtuxet Cove, Edgewood Yacht Club, Edgewood Shoal, Pomham Rocks, India Point Park and Phillipsdale Landing.

Dissolved oxygen conditions below the hypoxia threshold (2.9 mg/L) were observed in the lower part of the water column at Edgewood Yacht Club, Edgewood Shoal and Pomham Rocks. The entire water column at India Point Park and Phillipsdale Landing had dissolved oxygen concentrations below the hypoxia threshold. The highest fluorescence reading was observed 1.75 meters below the surface at Pawtuxet Cove.