Historical News
Surface Mapping
Data was collected on August 9, 2017 while the R/V Monitor was underway collecting bacteria samples and performing vertical profiles in the Providence and Seekonk River estuaries. The chlorophyll concentrations in areas surveyed ranged from fair to poor with highly variable concentrations below the Upper Providence River. From north to south, average chlorophyll concentrations were as follows: Seekonk River (4.63 µg/l), Upper Providence River (11.07 µg/l), Edgewood Shoals area (26.63 µg/l), Pawtuxet River area (28.86 µg/l), and the Lower Providence River (21.23 µg/l). Overall, chlorophyll ranged between 0 and 49.8 µg/l with an overall average of 16.45 µg/l. The chlorophyll data from this date is presented in the map below:
Water Column Profiles
Eight water column profiles were sampled in the Providence River Estuary on August 2, 2017. The five days prior to sampling were dry, with no precipitation. Most sites were well-mixed, with the exception of Pawtuxet Cove, India Point Park and Phillipsdale, which displayed slight stratification with fresher water at the surface. Salinities followed a general north to south gradient, with fresher waters near northern river outlets. Surface salinity ranged from 12.2 psu at India Point Park to 27.1 psu at Conimicut Point while bottom salinities ranged from 24.3 psu at Phillipsdale to 29.9 psu at Conimicut Point. Temperatures were pretty constant throughout the estuary. Surface temperatures ranged from 23.4°C at Conimicut Point and Bullock Reach to 25.1°C at India Point Park. Bottom temperatures ranged from 19.4°C at Conimicut Point to 22.7°C at Pawtuxet Cove. Fluorescence increased from the previous week, reaching a maximum of 53.19 mg/m3 at 1.5 m at India Point Park. The minimum fluorescence (0.76 mg/m3) was measured at 1.25 m at Edgewood Shoals. Overall, dissolved oxygen (DO) concentrations improved from the previous week. No sites were hypoxic throughout the water column and four sites, including Edgewood Yacht Club, Edgewood Shoals, India Point Park, and Phillipsdale, had hypoxic conditions at depth (<2.9 mg/L).
Water Column Clarity
Water clarity was measured at seven locations in the Providence and Seekonk Rivers on August 2, 2017. Weather was dry in the days preceding sampling. Overall, clarity showed a marked decrease compared to the previous survey, with Secchi depth averaging 1.1 meters versus 2.7 m the week before. The maximum water clarity (1.6 m) was observed at Conimicut Point and Pawtuxet Cove; the minimum water clarity (0.6 m) was observed at Phillipsdale Landing and India Point. Each individual site sampled decreased in water clarity compared to the previous survey, ranging from a 0.7 m decrease at Pawtuxet Cove and Conimicut Point, to a 2.7 m decrease at India Point.
Water Column Profiles
Eight water column profiles were taken in the Providence and Seekonk River estuaries on July 26th, 2017. There was 0.56 inches of rainfall in the five days prior to the survey. All sites displayed well mixed water columns and salinities and temperatures were similar throughout the bay. A minimum surface salinity of 22.7 psu was observed at the Point Street Bridge and a maximum of 26.1 psu at Pomham Rocks and Conimicut Point. Bottom salinities ranged from 24.3 psu to 29.7 psu. Temperatures throughout the bay were very uniform both from site to site and throughout the water columns, and were cooler than the previous week. All locations, except for Point Street Bridge, had water column temperatures between 19.9 – 21.1°C; the Point Street Bridge location had temperatures from 22.4 – 23.1oC. Dissolved Oxygen (DO) levels increased at some locations, but other locations had hypoxic conditions found throughout the water column. Point Street Bridge, India Point, and Phillipsdale all had DO levels below 2.9 mg/L throughout the entire water column. Pawtuxet Cove, Pomham Rocks, and Edgewood Yacht Club all had some hypoxic conditions measured in the water columns. Only Conimicut Point and Bullocks Reach did not show any hypoxic DO levels. Fluorescence was relatively low at all stations this week with maximum fluorescence values ranging from 0.7 – 5.0 ug/L range; the maximum fluorescence were observed at Bullocks reach and Conimicut Point.
Water Column Profiles
Six water column profiles were taken in the Providence River estuary on July 19th, 2017. There was 0.28 inches of rainfall in the five days prior to the survey. Most sites displayed well mixed water columns except for Edgewood Yacht Club where some stratification at about 3 m was noted. The lowest surface salinities were observed at the sites closest to freshwater sources, including Pawtuxet Cove with a surface salinity of 15.3 psu, and India Point with a surface salinity of 16.1 psu; the highest surface salinities was observed at Conimicut Point of 22.5 psu. Bottom salinities ranged from 20.1 psu to 29.5 psu at these same locations. Surface temperatures were slightly warmer than the previous week, ranging 24.2-25.8°C among the sites. Bottom waters were also warmer than last week, ranging between a minimum of 19.1°C to a maximum of 25.8oC at the shallowest site (Pawtuxet Cove). Dissolved Oxygen (DO) levels had a slight as compared to the previous survey, five of the six locations sampled had minimum near bottom DO concentrations at or below the hypoxic threshold of 2.9 mg/L. The minimum DO observed at all sites was 0.1 mg/L, in the bottom waters of Edgewood Yacht Club which had hypoxic conditions from 2.75 m down to the bottom at 5.0 m; this was the site at which stratification was noted. India Point also had poor DO levels from a depth of 3.0 m to the bottom at 8.5 m; bottom DO at this location was measured at 0.9 mg/L. Bullocks Reach, Conimicut Point, and Pomham Rocks had bottom DO levels between 2.4 – 2.8 mg/L. Pawtuxet Cove, which has considerable river input from the Pawtuxet River had excellent water column DO from 7.2 – 10.1 mg/L. Surface DO concentrations were good to fair on this day. Fluorescence was high overall this week at most sites, with maximum fluorescence values ranging from 9.0 – 30.8 ug/L range; the maximum fluorescence was obscured at Edgewood Yacht Club at about 2.0m.
