Historical News
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.
Fixed Site Network
Phillipsdale
At Phillipsdale, sonde data revealed fair to poor water quality conditions over the course of the week. There was about 0.51 inches of rainfall recorded for the week, with all of it falling on August 5th. Surface and bottom salinities declined throughout the week. Surface salinity began the week mainly around 15 psu, but decreased to an average of about 5 psu at weeks end, the overall average was 10.1 psu and ranged from 1.8 psu – 18.8 psu. Bottom salinity was affected by tidal fluctuations, though also exhibited an overall decrease throughout the week and had an average salinity of 21.0 psu and a range of 7.0 psu – 27.5 psu. Both surface and bottom temperatures increased from last week with surface temperatures averaging 23.8oC and a range of 19.0oC – 27.0oC; bottom temperatures had an average of 22.8oC and ranged between 20.3oC – 25.6oC. Surface chlorophyll increased throughout the week, peaking to about 27.0 ug/L on the 3rd , but was overall relatively low with a weekly average of 3.4 ug/L. Dissolved oxygen (DO) for the week was fair at the surface and was nearly hypoxic the entire week at the bottom. The surface did not have any readings below 2.9 mg/L and increased over the course of the week; the average surface DO was 7.7 mg/L and ranged from 3.2 mg/l to 14.1 mg/L. Dissolved oxygen in the bottom waters had a weekly average of 2.5 mg/l and ranged from a minimum of 0.5 mg/L to a maximum of 9.5 mg/L. Rolling and daily averages of bottom DO showed nearly constant hypoxic conditions this week, except for on the 3rd and 4th when daily average DO was above 3.4 mg/L. Note that tidal fluctuations and Blackstone River flow greatly influence bottom DO, temperature and salinity at this location.
Bullocks Reach
Water quality at Bullocks Reach was good this week. There was a generally uniform water column from surface to bottom with little to no stratification evident. Temperatures increased at each of the three depths with the surface water temperature averaging 23.2oC, mid water temperatures had an average of 22.5oC and bottom water temperatures averaged of 20.4oC Surface, mid and bottom salinities were relatively steady over the course of the week and averaged 26.5 psu, 27.7 psu, and 29.4 psu, respectively. Surface and bottom dissolved oxygen (DO) had a slight decline over the course of the week, whereas DO at the mid depth increased slightly. There was hardly any incidence of hypoxia at any of the depths, except for a few values around 2.9 mg/L on the 4th. Surface DO had a minimum of 4.8 mg/L, a maximum of 13.4 mg/L, and an average of 7.8 mg/L for the week. At the mid depth DO data showed good conditions with an average of 6.9 mg/L, a minimum of 4.2 mg/L and a maximum of 10.2 mg/L. The average weekly bottom DO was 4.3 mg/L and ranged between 2.8 mg/L to 6.4 mg/L. Surface chlorophyll peaked on the 31st at about 20 ug/L and then continued to decline over the course of the week, with a weekly average of 8.0 ug/L; mid chlorophyll peaked on the 1st at about 14 ug/L, with a weekly average of 7.5 ug/L.
