Historical News
Bacteria Sampling
On May 10, twenty stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers. Five of these stations were also sampled for enterococci bacteria. Precipitation in the five days prior to sampling totaled 0.26 inches as recorded at TF Green.
The geometric mean of fecal coliform results for all sites was 23 MPN/100 mL compared to 29 MPN/100 mL on April 26, 2023. Overall, bacteria counts were lower in the Seekonk River and Providence River this week than during the previous sampling event on April 26. Fecal coliform counts were 40 MPN/ 100 mL in the Seekonk River and 18 MPN/ 100 mL in the Providence River. 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 14 MPN/100 mL. Enterococci results were non-detect at all sites except the Point St. Bridge site with a measurement of 134 MPN/100 mL.
| | 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 |
Water Column Clarity
Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on May 10. Rainfall totaling 0.17 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 1.9 meters, compared to 1.4 meters on the previous survey (May 3). The lowest clarity this week (1.5 meters) was measured at Bullock Reach while the greatest clarity (2.1 meters) was measured at Conimicut Point, India Point Park, and Point St. Bridge. There was a general north-to-south gradient of decreasing water clarity among the sites this week.
Water Column Clarity
Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on May 3. Rainfall totaling 3.64 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 1.4 meters, compared to 2.5 meters on the previous survey (April 19). The lowest clarity this week (0.9 meters) was measured at India Point Park while the greatest clarity (1.7 meters) was measured at Pomham Rocks and Pawtuxet Cove. There was a general north-to-south gradient of increasing water clarity among the sites this week.
Phytoplankton Sampling
Phytoplankton samples were collected on May 3, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sondes data revealed the surface water temperature was 13.37⁰C, salinity was 6.62 psu, and chlorophyll a was 1.86 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a light brown color and had a quick filter time. There was lots of zooplankton activity in today’s sample. The tow net sample was analyzed qualitatively for microorganisms using phase contrast microscopy. The whole water sample was analyzed quantitatively under 200x phase contrast microscopy. A Hensen Stempel pipette was used to accurately deliver 1ml of sample to a Sedge-wick Rafter chamber. This analysis revealed a total of 214,000 cells per Liter. The micro flagellates were found at 7,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 87,000 cells/L. Representative genera in the tow net sample include Thalassionema spp., Leptocylindrus spp. and pennate diatoms.
Bacteria Sampling
On April 26, twenty stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers. Five of these stations were also sampled for enterococci bacteria. Precipitation in the five days prior to sampling totaled 0.91 inches as recorded at TF Green.
| | 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 |
