News – Page 4 – Narrabay

July 30, 2026

Surface chlorophyll data were collected on July 30, 2026, while the R/V Data Stream was underway collecting bacteria samples in the Providence and Seekonk River Estuaries. The chlorophyll concentrations were categorized as fair overall with most areas sampled having average chlorophyll concentrations between 5 µg/L and 20 µg/L, with the exception of the Seekonk River, which had average chlorophyll concentrations above 20 µg/L (categorized as poor). Overall, chlorophyll ranged from 3.63 µg/L to 128.48 µg/L with an average of 15.46 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

August 5, 2026

Water clarity was measured at eight locations in the Providence River and Seekonk River estuaries on August 5, 2026. In the five days prior to the survey, 2.57 inches of precipitation were recorded at TF Green. Secchi depth averaged 1.8 meters. The lowest clarity this week (1.2 meters) was measured at Pawtuxet Cove, while the greatest clarity (2.1 meters) was observed at Bullock Reach. 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 July 23, 2026).

June 10, 2026

Phytoplankton samples were collected on June 10, 2026 at Bullock’s Reach and analyzed in the laboratory shortly after collection.

On this day, the water temperature was 20.03 °C, the salinity was 27.2 PSU, and the chlorophyll a was 1.54 ug/L.

The qualitative tow net sample had a long filtration time and was cloudy and light golden brown in coloration.

The analysis of the quantitative whole water sample revealed a total of 5,570,000 cells/L. The microflagellates were found at 515,000 cells/L. The most predominant phytoplankton genera were Dactyliosolen spp. at 4,650,000 cells/L, Skeletonema spp. at 250,000 cells/L, and Chaetoceros spp. at 120,000 cells/L.

200x phase contrast image of Peridinium spp.

Peridinium spp. are cosmopolitan dinoflagellates mostly found in freshwater lakes, ponds and pools. Some inhabit brackish environments. This genus was originally described in the early 1830s, making it one of the first known groups of dinoflagellates. They are thought to be mixotrophic, which means they obtain energy through photosynthesis (autotrophy), and ingestion of small organisms (heterotrophy).

July 23, 2026

Surface chlorophyll data were collected on July 23, 2026, while the R/V Data Stream was underway collecting bacteria samples in the Providence and Seekonk River Estuaries. The chlorophyll concentrations were categorized as fair overall with most areas sampled having average chlorophyll concentrations between 5 µg/L and 20 µg/L, with the exception of the Seekonk River, which had average chlorophyll concentrations above 20 µg/L (categorized as poor). Overall, chlorophyll ranged from 4.51 µg/L to 77.03 µg/L with an average of 15.49 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

July 20 – July 26, 2026

Walkers Point

Overall, the water quality at Walkers Point was good to fair this week. Weather conditions were dry this week, except for 1.88 inches of precipitation recorded at T.F. Green on July 25^th. Surface salinity averaged 15.9 ppt and ranged from 6.3 ppt to 27.4 ppt. At the bottom, salinity averaged 26.4 ppt and ranged from 21.8 ppt to 29.5 ppt. Temperatures averaged 24.2°C at the surface and 23.7°C at the bottom. Surface temperatures ranged from 22.3°C to 26.7°C, while bottom temperatures ranged from 22.8°C to 24.3°C.

Dissolved oxygen (DO) at Walkers Point remained above the hypoxia threshold (i.e., DO>2.9mg/L) at the surface but dropped below at the bottom depth. The longest periods of hypoxic conditions spanned 49 hours and 46 minutes, occurring at the bottom depth between the evening of July 23^rd and July 25^th. During this period, the DO averaged around 1.59 mg/L. Surface DO averaged 10.4 mg/L and ranged from 4.7 mg/L to 18.7 mg/L. Bottom DO concentrations averaged 2.6 mg/L and ranged from 0.2 mg/L to 6.0 mg/L. Chlorophyll readings averaged 22.0 µg/L at the surface and 12.4µg/L at the bottom. Maximum chlorophyll at the surface reached 92.6 µg/L on the morning of July 24^th.

Bullock Reach

Sondes were swapped this week on the morning of July 23^rd. Overall, water quality was good to fair at Bullock Reach this week. Salinity averaged 27.6 ppt, 29.4 ppt, and 30.3 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 24.8 – 29.6 ppt, middle salinity range 26.1 – 31.2 ppt, and bottom salinity ranged 14.5 – 31.7 ppt. Surface temperature averaged 23.9°C and ranged from 22.9°C to 25.5°C. Middle temperature averaged 23.5°C and ranged from 22.0°C to 25.1°C. Bottom temperatures averaged 22.9°C and ranged from 22.0°C to 23.7°C.

Dissolved oxygen (DO) at Bullock Reach remained above the hypoxia threshold (i.e., DO>2.9mg/L) at all the depths. Surface DO averaged 9.3 mg/L and ranged 5.7 – 15.0 mg/L. Middle DO averaged 6.8 mg/L and ranged 4.1 – 11.7 mg/L. At the bottom, DO averaged 5.24 mg/L and ranged 3.79 – 7.22 mg/L. Chlorophyll readings ranged from low to elevated throughout the week. Readings averaged 13.2 µg/L at the surface, 16.5 µg/L at the middle, and 6.87 µg/L at the bottom. The maximum surface chlorophyll was 29.6 µg/L on the night of July 23^rd.

July 23, 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 July 23, 2026. In the five days leading up to this, there were 2.28 inches of rain recorded at T.F. Green International Airport (Warwick, RI). The water column was strongly stratified at Phillipsdale Landing, moderately stratified at Bullock’s Reach, India Point Park, and Pomham Rocks, and weakly stratified at Conimicut Point, Edgewood Yacht Club, and Pawtuxet Cove.

Dissolved oxygen conditions were slightly below the hypoxia threshold (2.9 mg/L) throughout the water column at Phillipsdale Landing and in the lower part of the water column at Edgewood Yacht Club, Pomham Rocks, Conimicut Point, and India Point Park. The highest fluorescence reading was observed about 1.75 meters below the surface at Phillipsdale Landing.

July 23, 2026

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on July 23, 2026. In the five days prior to the survey, 2.28 inches of precipitation were recorded at TF Green. Secchi depth averaged 1.2 meters. The lowest clarity this week (0.6 meters) was measured at Phillipsdale Landing, while the greatest clarity (1.9 meters) was observed at Pomham Rocks. There was no clear north-to-south gradient in water clarity among the sites this week. Overall, water clarity decreased from the previous measurements (data collected July 15, 2026).

June 24, 2026

Nutrient samples were collected from seven river stations and seven bay stations on June 24^th. All bay stations were sampled at the surface and bottom. In the five days prior to sampling, 2.01 inches of precipitation were recorded at T.F. Green.

Among the river stations sampled, the highest total nitrogen (TN) was observed at Blackstone River @ Slater Mill (1,545 ppb, average of duplicates). The highest total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) were observed at Pawtuxet River @ Broad St. (TDN = 1,480 ppb, DIN = 1,208 ppb). Higher TDN were observed at Woonasquatucket River @ Valley St. and Woonasquatucket River @ Manton Ave. Bridge; however, inconsistency between the TN and TDN results may indicate some reliability issues in those results. The lowest TN, TDN, and DIN were observed at Moshassuck River @ Footbridge at Mill St. (TN = 806 ppb, TDN = 864 ppb, DIN = 700.9). The lowest TDN and DIN were observed at Palmer River @ Rt. 6 (, average of duplicates).

Among the bay stations sampled, the highest surface TN was observed at Pawtuxet Cove and Phillipsdale Landing (1,150 ppb). The highest surface TDN and DIN were observed at Pawtuxet Cove (TDN = 1,020 ppb, DIN = 729.4). The lowest surface TN, TDN, and DIN were observed at Conimicut Point (TN = 554 ppb, TDN = 134 ppb, DIN = 72.9).

The next scheduled sampling date is July 8^th, 2026.

June 10, 2026

Nutrient samples were collected from twelve river stations and eight bay stations on June 10^th. All bay stations were sampled at the surface, and Pawtuxet Cove was sampled at the surface and bottom. In the five days prior to sampling, 0.22 inches of precipitation were recorded at T.F. Green.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed at Pawtuxet River @ Broad St. (TN = 1,690 ppb, TDN = 1,810 ppb, DIN = 1,502.6 ppb). The lowest TN was observed at Runnins River @Rt. 6 (516 ppb). The lowest TDN and DIN were observed at Palmer River @ Rt. 6 (TDN = 286.5 ppb, DIN = 51.3, average of duplicates).

Among the bay stations sampled, the highest surface TN, TDN, and DIN were observed at Pawtuxet Cove (TN = 1,200 ppb, TDN = 674 ppb, DIN = 761.9, average of duplicates). The lowest surface TN was observed at Conimicut Point (466 ppb). The lowest TDN was observed at Edgewood Shoal (<100 ppb). The lowest surface DIN was observed at seven of eight sites (13 ppb, reflecting minimum detection limits for DIN).

The next scheduled sampling date is June 24^th, 2026.

July 15, 2026

On July 15^th, 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, 0.03 inches of precipitation were recorded at TF Green.

Fecal coliform counts were higher in the Seekonk River, compared to the previous sampling on June 17^th (geometric mean of 204 MPN/100 mL compared to 46 MPN/100 mL on 6/17). Fecal coliform counts were similar in the Providence River, compared to the previous sampling (geometric mean of 8 MPN/100 mL on July 15^th compared to 9 on June 17^th).

Enterococci results had an overall geometric mean of 49 MPN/100 mL. Enterococci counts ranged from <10 MPN/100 mL at three sites to 717 MPN/100 mL at Phillipsdale Landing.

The next scheduled sampling date is July 29^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.