Water clarity was measured at eight locations in the Providence River and Seekonk River estuaries on October 25th, 2023. Rainfall totaling 1.14 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 3.6 meters, compared to 3.5 meters on the previous survey (October 18th). The lowest clarity this week (1.7 meters) was measured at Phillipsdale Landing, while the greatest clarity (6.1 meters) was measured at Bullock Reach. There was a general north-to-south gradient of increasing water clarity among the sites this week.
Surface chlorophyll data were collected on September 6, 2023 while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuaries. The average chlorophyll concentrations were categorized fair in the areas surveyed. Overall, chlorophyll ranged from 2.74 µg/L to 100.34 µg/L with an average of 13.59 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.
Phytoplankton samples were collected on September 6, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sonde data revealed the surface water temperature was 23.4°C, salinity was 24.5 psu, and chlorophyll a was 12.2 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a light brown greenish color and had a long filter time. 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 2,856,000 cells per Liter. The micro flagellates were found at 108,000 cells/L. The most predominant phytoplankton genus was Leptocylindrus spp.at 2,196,000 cells/L. Other representative genera include Skeletonema spp., Chaetoceros spp., and Eucampia spp., the subject of the 200x phase contrast micrograph shown below.
Water clarity was measured at eight locations in the Providence River and Seekonk River estuaries on October 18th, 2023. There was trace amounts of precipitation recorded at TF Green in the five days prior to the survey. Secchi depth averaged 3.5 meters, compared to 2.9 meters on the previous survey (October 11th). The lowest clarity this week (2.4 meters) was measured at Phillipsdale Landing and India Point, while the greatest clarity (4.8 meters) was measured at Conimicut Point and Bullock Reach. There was a general north-to-south gradient of increasing water clarity among the sites this week.
Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on October 11th, 2023. Rainfall totaling 0.36 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.9 meters, compared to 2.2 meters on the previous survey (October 4th). The lowest clarity this week (2.2 meters) was measured at Phillipsdale, while the greatest clarity (3.4 meters) was measured at Edgewood Yacht Club and Bullock Reach. There was a general north-to-south gradient of increasing water clarity among the sites this week.
Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on October 4th, 2023. Rainfall totaling 1.27 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.2 meters, compared to 2.6 meters on the previous survey (September 27th). The lowest clarity this week (1.4 meters) was measured at India Point, while the greatest clarity (2.7 meters) was measured at Edgewood Yacht Club. There was no clear north-to-south gradient in water clarity among the sites this week.
Water clarity was measured at six locations in the Providence River and Seekonk River estuaries on September 27th, 2023. Rainfall totaling 2.77 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.6 meters, compared to 2.5 meters on the previous survey (September 20th). The lowest clarity this week (2.2 meters) was measured at Phillipsdale Landing, Point Street Bridge, and India Point while the greatest clarity (3.0 meters) was measured at Edgewood Yacht Club. There was a general north-to-south gradient of increasing water clarity among the sites this week.
Water clarity was measured at eight locations in the Providence River and Seekonk River estuaries on September 20th, 2023. Rainfall totaling 1.55 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.5 meters, compared to 1.4 meters on the previous survey (September 14). The lowest clarity this week (1.3 meters) was measured at India Point, while the greatest clarity (3.4 meters) was measured at Bullock Reach. There was a general north-to-south gradient of increasing water clarity among the sites this week.
Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on September 14th, 2023. Rainfall totaling 1.23 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 1.4 meters, compared to 2.2 meters on the previous survey (September 16th). The lowest clarity this week (0.9 meters) was measured at Phillipsdale Landing, while the greatest clarity (1.6 meters) was measured at Point Street Bridge, Bullock Reach and Conimicut Point. There was no clear north-to-south gradient in water clarity among the sites this week.
On August 31st, six stations were sampled for fecal coliform bacteria in the Providence River; one of these stations was also sampled for enterococci bacteria. There was a smaller set of stations sampled than normal due to weather conditions. Precipitation in the five days prior to sampling totaled 0.14 inches as recorded at TF Green.
Overall, bacteria counts were higher in the Providence River this week than during the previous sampling event on August 16. The fecal coliform geomean for the Providence River was 110 MPN/100 mL this week. The maximum count (430 MPN/100 mL) was measured at the Save the Bay site in the Providence River.
Enterococci was only sampled at one site this week. Gaspee Point measured a non-detect enterococci count.
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
