Historical News
Week of April 9 - 15, 2023
Bacteria Sampling
On April 13, twenty stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers. Five of these stations were also sampled for enterococci bacteria. No precipitation was recorded at TF Green in the five days prior to sampling.
The geometric mean of fecal coliform results for all sites was 10 MPN/100 mL compared to 32 MPN/100 mL on March 29, 2023. Overall, bacteria counts were lower in both the Seekonk River and Providence River this week than during the previous sampling event on March 29. Fecal coliform counts were higher in the Seekonk River sites than in the Providence River sites (geometric means of 29 MPN/100 mL and 7 MPN/100 mL, respectively). The maximum count (430 MPN/100 mL) was measured at Point St. Bridge in the Providence River.
Enterococci results had an overall geometric mean of 11 MPN/100 mL. Enterococci results ranged from non-detect at Phillipsdale Landing, South FP East, Gaspee Point, and Conimicut Point to 20 MPN/100 mL at the Point St. Bridge site.
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 | Geometric mean ≤35 colonies/100 mL |
| Shellfishing | Geometric mean ≤14 MPN/100 mL | NO ENTEROCOCCI CRITERIA |
Table adapted from Rhode Island Water Quality Regulations (250-RICR-150-05-1); see regulations for complete details.
Week of December 25 – 31, 2022
Nutrients Sampling
Nutrient samples were collected from seven local river stations and one bay station on December 28th; additional bay sampling was cancelled due to freezing temperatures. The lone bay station (Phillipsdale Landing) was sampled at the surface and bottom. Leading up to sampling, there were 1.17 inches total precipitation recorded at T.F. Green on the 23rd and no precipitation on the 24th - 27th.
Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) concentrations were observed at Pawtuxet River @ Broad St. (TN = 1,580 ppb, TDN = 1,710 ppb, DIN = 1,350 ppb). The lowest TN was observed at Woonasquatucket River @ Valley St. (TN = 651 ppb); the lowest TDN and DIN were observed Woonasquatucket River @ Manton Ave. Bridge (TDN = 680 ppb, DIN = 463 ppb).
At the one bay station sampled, Phillipsdale Landing, surface TN was 1,130 ppb, surface TDN was 1,160 ppb, and surface DIN was 899 ppb.
Data from additional sampling dates (typically every two weeks) are pending analysis and writeup.
Week of December 11 – 17, 2022
Nutrients Sampling
Nutrient samples were collected from thirteen local river stations on December 14th; bay sampling was cancelled due to a small craft advisory. In the five days prior to sampling, 0.15 inches total precipitation were recorded at T.F. Green.
Among the stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) concentrations were observed at Ten Mile River @ Central Ave. (TN = 2,250 ppb, TDN = 2,420 ppb, DIN = 2,000 ppb). The lowest TN was observed at Woonasquatucket River @ Manton Ave. Bridge (TN = 620 ppb); the lowest TDN and DIN were observed at Blackstone River @ Slater Mill (TDN < 100 ppb, DIN = 27.6 ppb).
Data from additional sampling dates (typically every two weeks) are pending analysis and writeup.
Week of November 27 – December 3, 2022
Nutrients Sampling
Nutrient samples were collected from seven local river stations and seven bay stations on November 29th and 30th. All of the bay stations were sampled at the surface and bottom. The weather leading up to the sampling day included some rain, with 0.54 inches total precipitation recorded at T.F. Green from November 25th through 29th. The 30th was dry during the morning of sampling, with 0.93 inches of rain in the afternoon after sampling was completed.
Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) concentrations were observed at Ten Mile River @ Roger Williams Ave. (TN = 2,120 ppb, TDN = 2,400 ppb, DIN = 1,960 ppb). The lowest TN, TDN, and DIN were observed at Moshassuck River @ Higginson Ave. (TN = 488 ppb, TDN = 533 ppb, DIN = 324 ppb).
Among the bay stations sampled, the highest surface nitrogen concentrations were observed at Pawtuxet Cove (TN = 1,640 ppb, TDN = 1,580 ppb, DIN = 1,340 ppb). The lowest surface TN and DIN concentrations were observed at Conimicut Point (TN = 586 ppb, DIN = 331 ppb, average of duplicates); the lowest surface TDN concentration was observed at Bullock Reach Buoy (TDN = 481 ppb). Chlorophyll a concentrations at the surface bay stations were relatively low, averaging 0.481 μg/L across all sites with a maximum of 0.787 μg/L at Bullocks Reach Buoy.
Data from additional sampling dates (typically every two weeks) are pending analysis and writeup.
Week of April 16 - 22, 2023
Water Column Clarity
Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on April 19. Rainfall totaling 0.17 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.5 meters, compared to 3.0 meters on the previous survey (April 13). The lowest clarity this week (1.6 meters) was measured at Phillipsdale Landing and Pawtuxet Cove while the greatest clarity (3.4 meters) was measured at Bullock Reach. There was no clear north-to-south gradient in water clarity among the sites this week.
