Historical News

Week of July 14 - 20, 2019

Water Column Profiles

Water column profiles were measured at seven sites in the Seekonk and Providence Rivers on July 17, 2019. Density stratification was observed at all sites. 

Heavy rains (1.01 in.) fell five days prior to the survey date, but the weather was hot and dry after that. Surface temperatures reflected the warm summer weather, reaching 24°C at all sites; bottom temperatures ranged from 20°C at Conimicut Point up to 24°C at Pawtuxet Cove. The lowest salinity was observed at the surface at India Point Park (24 psu); maximum salinity was 30 psu measured at Conimicut Point. 

Dissolved oxygen (DO) improved slightly this week, though two sites, Edgewood Yacht Club and Edgewood Shoals, still exhibited hypoxic bottom waters. DO at these two sites averaged 1.7 mg/L at ~4.5-4.75 m and deeper. All other sites remained above the hypoxia threshold of 2.9 mg/L, though the bottom waters at several other sites were less than 4 mg/L. Fluorescence was lower than last week, suggesting a decline in phytoplankton bloom activity; the highest fluorescence measured was 13.9 mg/m3, at 0.75 m at Pomham Rocks.

Week of July 7 - 13, 2019

Water Column Profiles

Water column profiles were measured at seven sites in the Seekonk and Providence Rivers on July 10, 2019. The weather leading up to the survey date was hot and dry. Density stratification was observed at most sites, though the water column at Point St. Bridge and Edgewood Yacht Club was relatively well-mixed. 

Water temperatures reflected the warm sunny weather, with surface temperatures ranging from 22°C at India Point Park up to 26°C at Point St. Bridge; bottom temperatures ranged from 20°C at Conimicut Point, Pomham Rocks, and India Point Park up to 25°C at Point St. Bridge. Surface salinities were high at all sites, reflecting the low recent rainfall. The lowest salinity was observed at Phillipsdale Landing at 19 psu; surface salinity reached a maximum of 26 psu at Conimicut Point, Bullock Reach, and Edgewood Yacht Club. Bottom salinity was also highest at Conimicut Point (30 psu), while the lowest bottom salinity was measured at Point St. Bridge (23 psu). 

Dissolved oxygen (DO) declined this week, with several sites experiencing hypoxic bottom waters. The lowest DO was observed at Phillipsdale Landing, with the waters below 2.5 m averaging 1.2 mg/L. Phillipsdale was also experiencing the most phytoplankton activity of all sites, with fluorescence of 38.8 mg/m3 at 1.25 m; fluorescence was also elevated (~15-17 mg/m3) at Bullock Reach and Pomham Rocks. Additional sites with bottom waters below the hypoxic threshold of 2.9 mg/L included India Point Park, Point St. Bridge, Pomham Rocks, and Edgewood Yacht Club. 

Week of June 16 - 22, 2019

Nutrients Sampling

Nutrient samples were collected at fourteen local and border river stations and eight bay stations on June 19, 2019; seven bay stations were sampled at the surface only, with one station (Edgewood Shoals) sampled at the surface and bottom. The day before sampling was rainy, with 0.4 inches of rainfall recorded at TF Green.

Among the river stations, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) values were measured in samples from the Ten Mile River at Central Ave., with values of 1,350 ppb, 1,360 ppb, and 1,035 ppb, respectively. The lowest TN result (603 ppb) was measured in the sample from the Moshassuck River at Higginson Ave. The lowest TDN and DIN were measured in samples from the Palmer River at Rt. 6 (304 ppb and 131 ppb, respectively; average of duplicates).

At the bay surface sites, Phillipsdale Landing had the highest concentration of TN (1,010 ppb; average of duplicates), while the highest TDN (892 ppb) and DIN (699 ppb) concentrations were observed in the samples from Pawtuxet Cove. Conimicut Point had the lowest TN and DIN concentrations (680 ppb and 13 ppb, respectively), while several stations had TDN concentrations below detection (i.e., <100 ppb; Conimicut Point, Edgewood Yacht Club, and Bullock Reach). Chlorophyll concentrations increased since the last survey indicating greater phytoplankton activity, with a maximum of 32.54 ug/L at Edgewood Yacht Club and an overall average of 19.3 ug/L.

Week of July 7 - 13, 2019

Bacteria Sampling

​Twenty stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers on July 10, 2018. Weather leading up to the sampling day was dry, with just 0.02 inches of rainfall recorded over the five days prior. 

Overall, fecal coliform bacteria counts were lower than the previous sampling event on June 26. The geometric mean for all sites was 44 MPN/100 mL; fecal coliform counts were higher at Seekonk River sites than Providence River (geometric means of 187 and 22 MPN/100 mL, respectively). The maximum count (930 MPN/100 mL) was measured at the Point St. Bridge. Despite that elevated result, overall the Providence River results were within state standards for primary contact.​

The enterococci geometric mean for the Seekonk and Providence Rivers also decreased from the previous sampling, from 35 MPN/100 mL to 15 MPN/100 mL. Enterococci concentrations ranged from <10 MPN/100 mL at most sites to 171 MPN/100 mL at Point St. Bridge. This elevated result exceeds state standards for primary contact.

Please note: the results of NBC's fecal coliform and enterococci monitoring are for informational/research purposes only and are not intended to suggest official state compliance with bathing or shellfishing standards.

Week of July 14 - 20, 2019

Surface Mapping

Data was collected on July 17, 2019 while the R/V Monitor was underway collecting nutrient samples and performing vertical profiles in the Providence River estuary. The chlorophyll concentrations were slight variable but fair. From north to south, average chlorophyll concentrations were as follows: Upper Providence River (10.73 µg/l), Edgewood Shoals area (12.16 µg/l), Pawtuxet River area (7.79 µg/l), and the Lower Providence River (9.19 µg/l). Overall, chlorophyll ranged between 3.60 µg/l and 15.00 µg/l with an overall average of 9.99 µg/l. The chlorophyll data from this date is presented in the map below:

Dataflow 2019-07-17_small.jpg 

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