News – Page 8 – Narrabay

April 23, 2025

On April 23rd, 2025, 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, 0.05 inches of precipitation was recorded at TF Green. Overall bacteria counts were lower than during the previous sampling event.

Fecal coliform counts were higher in the Seekonk River, compared to the Providence River (geometric mean of 72 MPN/100 mL for the Seekonk River compared to 12 MPN/100mL for the Providence River) for sampling conducted on April 23rd. The maximum count (430 MPN/100 mL) was measured at the Point Street Bridge sampling location.

Fecal coliform counts were lower in the Providence River, compared to the previous sampling on March 26th (geometric mean of 12 MPN/100 mL compared to 38 MPN/100 mL on 3/26). Fecal coliform counts were higher in the Seekonk River, compared to the previous sampling on March 26th (geometric mean of 72 MPN/100 mL compared to 67 MPN/100 mL on 3/26).

Enterococci results had an overall geometric mean of 12 MPN/100 mL. Enterococci counts ranged from <10 MPN/100 mL at most sites to 20 MPN/100 mL at Point St Bridge.

The next scheduled sampling date is May 7th.

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.

June 11, 2025

Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on June 11, 2025 using a Seabird Electronics profiler. In the five days leading up to the survey, 0.85 inches of precipitation were recorded at T.F. Green. Water column stratification varied between the sites this week from moderately stratified at India Point Park and Phillipsdale Landing to strongly stratified at all other sites.

Dissolved oxygen (DO) conditions were not observed to be below the hypoxia threshold (2.9 mg/L) at any site profiled this week. The highest fluorescence recorded this week was measured around 2 meters below the surface at Bullock Reach Buoy.

June 4, 2025

Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on June 4, 2025 using a Seabird Electronics profiler. In the five days leading up to the survey, 0.39 inches of precipitation were recorded at T.F. Green. Water column stratification varied between the sites this week from weakly stratified at Point Street Bridge to strongly stratified at all other sites.

May 28, 2025

Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on May 28, 2025 using a Seabird Electronics profiler. In the five days leading up to the survey, 0.15 inches of precipitation were recorded at T.F. Green. Water column stratification varied between the sites this week from moderately stratified at Bullock Reach Buoy and India Point Park to strongly stratified at all other sites.

June 11, 2025

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on June 11, 2025. In the five days prior to the survey, 0.85 inches of precipitation were recorded at TF Green. Secchi depth averaged 2.4 meters. The lowest clarity this week (2.1 meters) was measured at Phillipsdale Landing, while the greatest clarity (2.9 meters) was measured at India Point Park. There was no clear north-to-south gradient in water clarity among the sites this week. Overall, water clarity among most sites remained relatively consistent compared to previous measurements (data collected June 4, 2025). However, water quality at Point Street Bridge decreased (1.1 meters) and water quality at Bullock’s Reach decreased (1.3 meters), both compared to previous measurements (data collected June 4, 2025).

June 4, 2025

Water clarity was measured at eight locations in the Providence River and Seekonk River estuaries on June 4, 2025. In the five days prior to the survey, 0.39 inches of precipitation were recorded at TF Green. Secchi depth averaged 2.6 meters. The lowest clarity this week (1.9 meters) was measured at Phillipsdale Landing, while the greatest clarity (3.5 meters) was measured at Point Street Bridge and Bullock’s Reach. There was no clear north-to-south gradient in water clarity among the sites this week. Overall, water clarity remained approximately the same from the previous measurements (data collected May 28, 2025).

May 28, 2025

Water clarity was measured at eight locations in the Providence River and Seekonk River estuaries on May 28, 2025. In the five days prior to the survey, 0.15 inches of precipitation were recorded at TF Green. Secchi depth averaged 2.5 meters. The lowest clarity this week (1.7 meters) was measured at Phillipsdale Landing, while the greatest clarity (2.9 meters) was measured at Edgewood Shoal. There was no clear north-to-south gradient in water clarity among the sites this week. Overall, water clarity among most sites remained relatively consistent compared to previous measurements (data collected May 21, 2025). However, water quality at Conimicut Point decreased (1.2 meters) from the previous measurements (data collected May 21, 2025).

May 21, 2025

Water clarity was measured at eight locations in the Providence River and Seekonk River estuaries on May 21, 2025. In the five days prior to the survey, 0.04 inches of precipitation were recorded at TF Green. Secchi depth averaged 2.8 meters. The lowest clarity this week (2.1 meters) was measured at Phillipsdale Landing, while the greatest clarity (3.9 meters) was measured 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 May 14, 2025).

May 14, 2025

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on May 14, 2025. In the five days prior to the survey, 1.73 inches of precipitation were recorded at TF Green. Secchi depth averaged 2.0 meters. The lowest clarity this week (1.7 meters) was measured at Phillipsdale Landing, Edgewood Yacht Club, and Bullock’s Reach, while the greatest clarity (2.5 meters) was measured at Conimicut Point. 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 May 7, 2025).

September 16 – 22, 2024

Phillipsdale Landing

Sondes were swapped this week on the morning of September 17^th. Overall, water quality at Phillipsdale Landing was good to fair this week. Weather conditions included sporadic rain events, with 0.78 inches of precipitation recorded at T.F. Green. The Blackstone River flow remained below the 20-year daily median. Surface salinity averaged 24.3 ppt and ranged from 20.4 ppt to 28.3 ppt. At the bottom, salinity averaged 26.3 ppt and ranged from 22.9 ppt to 29.6 ppt. Temperatures continued to decline this week, averaging 21.3°C at the surface and ranging 18.5°C – 24.0°C. At the bottom, temperatures averaged 21.4°C and ranged 19.2°C – 23.5°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO average 5.97 mg/L and ranged from 3.93 mg/L to 10.82 mg/L. Bottom DO concentrations averaged 5.0 mg/L and ranged from 3.3 mg/L to 8.5 mg/L. Chlorophyll readings decreased from last week, averaging 16.01 µg/L at the surface and 12.8 µg/L at the bottom. Maximum chlorophyll at the surface reached 57.03 µg/L on the evening of September 17^th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Overall, water quality was good to fair at Bullock Reach this week. Salinity averaged 28.7 ppt, 29.2 ppt, and 30.5 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 27.5 – 29.7 ppt, mid salinity ranged 27.9 – 30.1 ppt, and bottom salinity ranged 29.0 – 31.4 ppt. Surface temperature averaged 21.0°C and ranged from 19.2°C to 23.1°C. Mid temperatures averaged 20.8°C and ranged from 19.1°C to 22.1°C. Bottom temperatures averaged 20.4°C and ranged from 19.1°C to 21.6°C.

DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week Surface DO averaged 6.7 mg/L and ranged 5.5 – 10.2 mg/L. In the mid waters, DO averaged 6.1 mg/L and ranged 4.6 – 8.7 mg/L. At the bottom, DO averaged 5.6 mg/L and ranged 3.8 – 6.7 mg/L. Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 5.5 µg/L at the surface, 6.2 µg/L at mid-depth, and 6.7 µg/L at the bottom. The maximum surface chlorophyll was 17.5 µg/L on the afternoon of September 16^th.