News – Page 16 – Narrabay

June 5, 2024

On June 5th, 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, there was no precipitation recorded at TF Green. Overall, bacteria counts were higher in both the Seekonk and Providence Rivers than during the previous sampling event.

Fecal coliform counts were higher in the Seekonk River sites than in the Providence River sites (geometric means of 204 MPN/100 mL and 13 MPN/100 mL, respectively). The maximum counts (930 MPN/100 mL) were measured at Bishop Point and Off BP Outfall.

Enterococci results had an overall geometric mean of 28 MPN/100 mL. Enterococci counts ranged from <10 MPN/100 mL at Gaspee Point and Conimicut Point to 158 MPN/100 mL at Point St Bridge.

The next scheduled sampling date is June 17.

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.

May 22, 2024

On May 22nd, 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, precipitation totaled 0.27 inches as recorded at TF Green. Overall, bacteria counts were higher in both the Seekonk and Providence Rivers than during the previous sampling event on April 24th.

Fecal coliform counts were higher in the Seekonk River sites than in the Providence River sites (geometric means of 135 MPN/100 mL and 52 MPN/100 mL, respectively). The maximum count (430 MPN/100 mL) was measured at Collier Point Park.

Enterococci results had an overall geometric mean of 15 MPN/100 mL. Enterococci counts ranged from <10 MPN/100 mL at Conimicut Point to 85 MPN/100 mL at Phillipsdale Landing.

The next scheduled sampling date is June 5.

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

Table adapted from Rhode Island Water Quality Regulations (250-RICR-150-05-1); see regulations for complete details.

November 18, 2024

The Data Stream deployed on a chilly but otherwise beautiful November day. The team retrieved the Bullock’s Reach Sondes for the final time in the 2024 season. The buoy is scheduled to be removed from the water for the winter in early December. The picture below was taken while on route. In the distant background, accentuated by a rainbow, you can see the wind turbines from Johnson & Wales University and Narragansett Bay Commission’s Field’s Point Wastewater Treatment Facility.

November 7, 2024

Surface chlorophyll data were collected on November 7, 2024, while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuary. The average chlorophyll concentrations were categorized as good in all areas surveyed. Overall, chlorophyll ranged from 0.53 µg/L to 17.57 µg/L with an average of 2.89 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

October 30, 2024

Phytoplankton samples were collected on October 30, 2024 at Bullock’s Reach and analyzed in the laboratory shortly after collection. Weather conditions and Sonde data were not recorded on this day. The qualitative tow net sample had a moderate filtration time. The filtrate was slightly cloudy with some golden brown particulates. The analysis of the quantitative whole water sample revealed a total of 260,000 cells/L. The microflagellates were found at 100,000 cells/L. The most predominant phytoplankton genera were Chaetoceros spp. at 104,000 cells/L, Leptocylindrus spp. at 26,000 cells/L, and Skeletonema spp. at 18,000 cells/L. Proboscia alata, shown here in a 100x phase contrast micrograph, is a solitary or chain-forming diatom that can measure up to 1mm in length. They are identified by the presence of a proboscis with a truncated tip and offset claspers. These diatoms are an oceanic, temperate water species and are sometimes found near the coast.

October 30, 2024

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on October 30, 2024. In the five days prior to the survey, 0.03 inches of precipitation were recorded at TF Green. Secchi depth averaged 5.5 meters. The lowest clarity this week (2.9 meters) was measured at Phillipsdale Landing, while the greatest clarity (8.5 meters) was measured at Bullock Reach Buoy. There was a general north-to-south trend of increasing water clarity among the sites this week. Overall, water clarity increased from the previous measurements (data collected October 23, 2024).

October 9, 2024

The crew of the Data Stream were performing routine bacteria sampling when they observed two bald eagles flying high in the sky above the Seekonk River near Phillipsdale Landing in East Providence.

October 3, 2024

Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on October 3, 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 to weakly stratified.

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 readings for the week were measured around 1 meter below the surface at Edgewood Yacht Club.

September 25, 2024

Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on September 25, 2024 using a Seabird Electronics profiler. In the five days leading up to the survey, 0.78 inches of precipitation were recorded at T.F. Green. Water column stratification at the sites varied from well-mixed to weakly stratified.

Dissolved oxygen (DO) conditions were below the hypoxia threshold (2.9 mg/L) in the lower portion of the water column at Edgewood Yacht Club and Pomham Rocks. The highest fluorescence readings for the week were measured around 1 meter below the surface at Pawtuxet Cove.

October 17, 2024

Phytoplankton samples were collected on October 17, 2024 at Bullock’s Reach and analyzed in the laboratory shortly after collection. It was windy and brisk on Narragansett Bay. Sonde data revealed the surface water temperature was 14.63°C, salinity was 30.01 psu, and chlorophyll a was 2.58 ug/L. The qualitative tow net sample had a quick filtration time and the filtrate was clear. The analysis of the quantitative whole water sample revealed a total of 156,000 cells/L. The microflagellates were found at 48,000 cells/L. The most predominant phytoplankton genera were Prorocentrum spp. at 38,000 cells/L, Leptocylindrus spp. at 16,000 cells/L, and Cylindrotheca spp. at 12,000 cells/L. Corethron hystrix, shown here in a 200x phase contrast micrograph, is a solitary species of centric diatom found in the North Atlantic and North Pacific, typically in the spring and fall. They have a unique pill shape and two rings of long spines directed towards one end, and a crown of shorter, hooked spines pointed in the opposite direction. Although they do not bloom in large numbers, it has been observed that they may cause physical obstructions in the gills of farmed salmon.