Water clarity was measured at five locations in the Providence River and Seekonk River estuaries on August 16. Rainfall totaling 0.61 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.8 meters, compared to 1.8 meters on the previous survey (August 9). The lowest clarity this week (1.9 meters) was measured at Phillipsdale Landing, while the greatest clarity (3.6 meters) was measured at Point St. Bridge. There was no clear north-to-south gradient in water clarity among the sites this week.
On August 16, 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 0.61 inches as recorded at TF Green.
The geometric mean of fecal coliform results for all sites was 149 MPN/100 mL compared to 41 MPN/100 mL on August 2. Overall, bacteria counts were higher in both the Seekonk and Providence Rivers this week than during the previous sampling event on August 2. Fecal coliform counts were geomeans of 435 MPN/ 100 mL in the Seekonk River and 90 MPN/ 100 mL in the Providence River. The maximum count (9300 MPN/100 mL) was measured at Bullock Reach Buoy in the Providence River.
Enterococci results had an overall geometric mean of 35 MPN/100 mL. Enterococci counts ranged from non-detect at a Gaspee Point and Conimicut Point to 238 MPN/100 mL at Point St. Bridge.
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
Surface chlorophyll data were collected on August 16, 2023 while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuaries. The average chlorophyll concentrations were categorized as good in the Seekonk River and Northern Providence River Channel and as fair in all others. Overall, chlorophyll ranged from 1.46 to 17.84 µg/L with an average of 5.21 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.
*Due to file error the lowest portion of the boat path for this survey is not displayed.
Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on March 20, 2024 using a Seabird Electronics profiler. In the five days leading up to the survey, 0.08 inches of precipitation were recorded at T.F. Green. Most sites were strongly or moderately stratified this week, with the exception of Phillipsdale Landing, which was dominated by freshwater.
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 2 meters below the surface at Bullock Reach Buoy.
Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on March 6, 2024 using a Seabird Electronics profiler. In the five days leading up to the survey, 2.30 inches of precipitation were recorded at T.F. Green. Most sites were strongly stratified this week, with the exception of Phillipsdale Landing, which was dominated by freshwater, showing the impact of over 2 inches over rain that fell in the days before the profiles were recorded.
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 1.5 meters below the surface at Conimicut Point.
Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on December 13, 2023 using a Seabird Electronics profiler. In the five days leading up to the survey, 2.29 inches of precipitation were recorded at T.F. Green. Most sites were strongly stratified this week, with the exception of Pawtuxet Cove, which was dominated by freshwater, showing the impact of the major rain storm this week.
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 3 meters below the surface at Phillipsdale Landing.
Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on November 30, 2023 using a Seabird Electronics profiler. In the five days leading up to the survey, 0.69 inches of precipitation were recorded at T.F. Green. Most sites were weakly or moderately stratified this week, with the exception of Pawtuxet Cove, which was strongly 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 1.5 meters below the surface at Pawtuxet Cove.
Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on November 15, 2023 using a Seabird Electronics profiler. In the five days leading up to the survey, 0.01 inches of precipitation were recorded at T.F. Green. Stratification ranged from well-mixed at sites like Bullock Reach Buoy to moderately stratified at sites including Phillipsdale Landing and Pomham Rocks.
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 3 meters below the surface at Edgewood Shoal.
Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on November 1, 2023 using a Seabird Electronics profiler. In the five days leading up to the survey, 1.11 inches of precipitation were recorded at T.F. Green. Most sites were moderately stratified this week, with the exception of Phillipsdale Landing, and Pawtuxet Cove, which were strongly 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 India Point Park.
Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on October 25, 2023 using a Seabird Electronics profiler. In the five days leading up to the survey, trace amounts of precipitation were recorded at T.F. Green. Stratification varied between the profiled sites this week, from weak stratification at Pomham Rocks and Point Street Bridge, to strong stratification at India Point Park, Phillipsdale Landing, and Pawtuxet Cove.
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 1.5 meters below the surface at Pawtuxet Cove.
