Tara Franey – Narrabay

December 18, 2024

On December 18^th, 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 20^th (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 20^th (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

	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.

March 19, 2025

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. — 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.

November 14, 2024

Phytoplankton samples were collected on November 14, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection.

It was partly sunny, windy and cold on this day. Sonde data was not recorded.

The qualitative tow net sample had a quick filtration time and the filtrate contained some light brown particulates and plant matter.

The analysis of the quantitative whole water sample revealed a total of 288,000 cells/L. The microflagellates were found at 30,000 cells/L. The most predominant phytoplankton genera were Chaetoceros spp. at 34,000 cells/L, Leptocylindrus spp. at 76,000 cells/L, and Heterocapsa spp. at 26,000 cells/L.

200x phase contrast micrograph of *Staurastrum* spp.

Staurastrum, shown here in a 200x phase contrast micrograph, is a large genus of microscopic green algae which are closely related to land plants. They are found in freshwater habitats around the world and live primarily in acidic lakes, ponds and swamps with low nutrient levels. Many Staurastrum species serve as indicators of eutrophic conditions.

February 19, 2025

Nutrient samples were collected from six river stations on February 19^th. No samples were collected from bay stations due to adverse weather conditions. In the five days prior to sampling, 1.98 inches of precipitation were recorded at T.F. Green.

The highest total nitrogen (TN), total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) concentrations were observed at Blackstone River @ Slater Mill (TN = 1,810 ppb, TDN = 1,960 ppb, DIN = 1,533 ppb). The lowest TN, TDN and DIN concentrations were observed at Woonasquatucket River @ Manton Ave. Bridge (TN =625 ppb, TDN = 711 ppb, DIN = 480 ppb).

The next scheduled sampling date is March 5, 2025.

February 5, 2025

Nutrient samples were collected from twelve river stations on February 5^th. No samples were collected from bay stations due to adverse weather conditions. In the five days prior to sampling, 0.74 inches of precipitation were recorded at T.F. Green.

The highest total nitrogen (TN), total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) concentrations were observed at Ten Mile River @ Central Ave. (TN = 3,160 ppb, TDN = 3,890 ppb, DIN = 3,148 ppb). The lowest TN, TDN and DIN concentrations were observed at Coles River @ Milford Rd. (TN =663 ppb, TDN = 727 ppb, DIN = 289 ppb).

The next scheduled sampling date is February 19, 2025.

October 30, 2024

Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on October 30, 2024 using a Seabird Electronics profiler. In the five days leading up to the survey, no precipitation was recorded at T.F. Green. Water column stratification varied between the sites this week from well-mixed at most sites to weakly stratified at Phillipsdale Landing.

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 meter below the surface at Phillipsdale Landing.

October 23, 2024

Water column profiles were conducted at six locations in the Providence River estuary on October 23, 2024 using a Seabird Electronics profiler. A seventh site, Point Street Bridge, was visited, but no data was collected due to an equipment malfunction. In the five days leading up to the survey, no precipitation was recorded at T.F. Green. Water column stratification varied between the sites this week from well-mixed at Pawtuxet Cove to moderately stratified at India Point Park.

January 22, 2025

Nutrient samples were collected from six river stations on January 22^th. No samples were collected from bay stations due to adverse weather conditions. In the five days prior to sampling, 0.79 inches of precipitation were recorded at T.F. Green.

The highest total nitrogen (TN), total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) concentrations were observed at Pawtuxet River @ Broad St. (TN = 1,920 ppb, TDN = 2,110 ppb, DIN = 1,734 ppb). The lowest TN and DIN concentrations were observed at Moshassuck River @ Footbridge at Mill St. (TN =777 ppb, DIN = 657 ppb). The lowest TDN concentration was observed at Woonasquatucket River @ Manton Ave. Bridge (896 ppb).

The next scheduled sampling date is February 5, 2025.

January 8, 2025

Nutrient samples were collected from eleven river stations on January 8^th. No samples were collected from bay stations due to adverse weather conditions. In the five days prior to sampling, trace amounts of precipitation were recorded at T.F. Green.

The highest total nitrogen (TN), total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) concentrations were observed at Ten Mile River @ Central Ave. (TN = 2,760 ppb, TDN = 2,970 ppb, DIN = 2,729 ppb – averages of duplicates). The lowest TN, TDN and DIN concentrations were observed at Coles River @ Milford Rd. (TN = 641 ppb, TDN = 650 ppb, DIN = 209 ppb).

The next scheduled sampling date is January 22, 2025.

December 24, 2024

Nutrient samples were collected from seven river stations on December 24^th. No samples were collected from bay stations due to adverse weather conditions. In the five days prior to sampling, 0.28 inches of precipitation were recorded at T.F. Green.

The highest total nitrogen (TN) and total dissolved nitrogen (TDN) were observed at Blackstone River @ Stateline (TN = 1,290 ppb, TDN = 1,360 ppb). The highest dissolved inorganic nitrogen (DIN) concentration was observed at Pawtuxet River @ Broad St. (964 ppb). The lowest TN, TDN and DIN concentrations were observed at Woonasquatucket River @ Manton Ave. Bridge (TN = 655 ppb, TDN = 670 ppb, DIN = 397 ppb).

The next scheduled sampling date is January 8, 2025.