Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on June 25, 2025 using a Seabird Electronics profiler. In the five days leading up to the survey, 0.01 inches of precipitation were recorded at T.F. Green. Water column stratification varied between the sites this week from weakly stratified at Pawtuxet Cove to strongly stratified at Conimicut Point, Pomham Rocks, and Phillipsdale Landing.
Dissolved oxygen (DO) conditions were below the hypoxia threshold (2.9 mg/L) in the lower portion of the water column at India Point Park and Phillipsdale Landing. The highest fluorescence readings for the week were measured around 1 meter below the surface at Phillipsdale Landing.
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.
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.
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 1.5 meters below the surface at Pomham Rocks.
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.
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 3 meters below the surface at Conimicut Point.
Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on May 21, 2025 using a Seabird Electronics profiler. In the five days leading up to the survey, less than 0.1 inches of precipitation were recorded at T.F. Green. Water column stratification varied between the sites this week from weakly stratified at Phillipsdale Landing and Pawtuxet Cove to well-mixed 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 2.5 meters below the surface at Pomham Rocks.
Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on May 14, 2025 using a Seabird Electronics profiler. In the five days leading up to the survey, 1.73 inches of precipitation were recorded at T.F. Green. Strong stratification of the water column stratification was observed at all 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 Conimicut Point.
Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on May 7, 2025 using a Seabird Electronics profiler. In the five days leading up to the survey, 2.1 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.
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 1.5 meters below the surface at Edgewood Yacht Club.
Phytoplankton samples were collected on April 17, 2025 at Bullock Reach and analyzed in the laboratory shortly after collection.
It was sunny, clear and breezy on this day. The water temperature was 6.11 degrees Celsius, and Sonde data was not recorded.
The qualitative tow net sample had a moderate filtration time and the filtrate was golden brown with some particulates.
The analysis of the quantitative whole water sample revealed a total of 590,000 cells/L. The microflagellates were found at 337,000 cells/L. The most predominant phytoplankton genera were Dinoflagellate spp. at 93,000 cells/L, Thalassiosira spp. at 44,000 cells/L, and Chaetoceros spp. at 43,000 cells/L.
200x phase contrast micrograph of Pleurosigma spp.
Pleurosigma is a genus of marine pelagic diatoms which are shaped like an elongated diamond. They are present throughout the world and breed particularly well in bays, inlets and ports. These diatoms are motile, and they employ a pulsating of the body to induce gliding movement as well as occasional circular rotations around one end of the organism to change course.
On December 18th, 2024, fifteen stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers; four of these stations were also sampled for enterococci bacteria. Further sampling was planned for the day in the Seekonk River, but was omitted due to weather issues. In the five days prior to sampling, 0.46” of precipitation was recorded at TF Green.
Fecal coliform counts were higher in the Providence River, compared to the previous sampling on November 20th (geometric mean of 91 MPN/100 mL compared to 9 MPN/100 mL on 11/20). The maximum count (430 MPN/100 mL) was measured at the Save the Bay sampling location.
Only one fecal coliform sample was analyzed from the Seekonk River, with a fecal coliform count of 43 MPN/100mL at Crook Point. This is higher than the geometric mean from samples taken on November 20th (14 MPN/100 mL), but may not be representative of the Seekonk River as a whole.
Enterococci results had an overall geometric mean of 66 MPN/100 mL. Enterococci counts ranged from 37 MPN/100 mL at Conimicut Point (geometric mean of two samples) to 121 MPN/100 mL at Point St. Bridge.
The next scheduled sampling date is January 2.
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
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.
Phytoplankton samples were collected on March 19, 2025 at Bullock Reach and analyzed in the laboratory shortly after collection.
It was sunny and cold on this day. The water temperature was 6.6 degrees Celsius, and jellyfish were observed. Sonde data was not recorded.
The qualitative tow net sample had a moderate to long filtration time and the filtrate was cloudy and dark brown with a large amount of sediment.
The analysis of the quantitative whole water sample revealed a total of 4,744,000 cells/L. The microflagellates were found at 86,000 cells/L. The most predominant phytoplankton genera were Leptocylindrus spp. at 2,918,000 cells/L, Chaetoceros spp. at 1,474,000 cells/L, and Skeletonema spp. at 144,000 cells/L.
200x phase contrast micrograph of Pyrocystis spp.
Pyrocystis spp., shown here in a 200x phase contrast micrograph, are non-motile, tropical, epipelagic marine dinoflagellates. They exhibit bioluminescence, which means emitting light through a chemical reaction, when they are disturbed or agitated. This is an unusual defense mechanism against predation which aims to startle grazers who would otherwise eat them.
