Historical News
Surface Mapping
Data
were collected on October 16, 2019 while the R/V Monitor was underway
collecting bacteria samples in the Providence and Seekonk River estuaries. The chlorophyll concentrations were good. From north to south, average chlorophyll
concentrations were as follows: Seekonk River (2.84 µg/L), Upper Providence
River ( 2.29 µg/L), Edgewood Shoals area (3.17 µg/L), Pawtuxet River area (3.64
µg/L), and Lower Providence River area (3.50 µg/L). Overall, chlorophyll ranged
between 0.90 and 5.60 µg/L with an overall average of 2.90 µg/L. The
chlorophyll data from this date are presented in the map below:
R/V Monitor's Blog
The R/V Monitor was out on the upper Bay twice this week. First, on Tuesday, October 15th, the crew conducted video transects of the benthic community using the NBC designed and built camera sled. A total of three transects were conducted this day. Benthic videos are regularly conducted and over time, these videos will help evaluate health improvements of the benthic community resulting from water quality improvements in the upper Bay. Jeff captained the boat while monitoring professionals Bekki, Fern and Gerard operated the equipment. It was a perfect day for this work, as it was sunny and windless with very calm waters. On Wednesday, October 16th, the crew was out collecting bacteria samples, taking Secchi Disk and Par sensor water clarity measurements, and conducting real-time surface mapping of water quality parameters, including dissolved oxygen, chlorophyll, water temperature, salinity, and pH, all in an effort to document water quality improvements associated with NBC construction projects. Jeff captained the boat while monitoring professionals Fern, Mike and Gerard collected the samples and data. The day started sunny and calm, but the wind, and waves, picked up considerably by noontime. Today's photo features the I-195 Iway bridge as seen from the south.
Bacteria Sampling
Twenty stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers on October 2, 2019. Five stations were also sampled for enterococci. Five days prior to sampling, moderate rainfall of 0.36 inches occurred.
The geometric mean of fecal coliform results for all sites was 16 MPN/100 mL; counts were higher at the Seekonk River sites than the Providence River sites (geometric means of 37 and 10 MPN/100 mL, respectively). The maximum count (230 MPN/100 mL) was measured at several locations – off Bucklin Point outfall, at Bishop Point, and at Point St. Bridge. Results from both the Providence and Seekonk Rivers were within state standards for primary contact, however, results from the Seekonk River exceeded state standards for shellfishing.
The enterococci results increased slightly from the previous sampling event on September 18, from 12 MPN/100 mL to 15 MPN/100 mL. Enterococci results ranged from <10 MPN/100 mL in at least one sample from Gaspee Point, Conimicut Point, and Phillipsdale Landing to 74 MPN/100 mL at Point St. Bridge. These enterococci results were within 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.
Fixed Site Network
Water quality was fair to good this week at Phillipsdale Landing. Approximately 0.6 inches of precipitation occurred over the course of the week, with some rainfall observed on September 24 and 26. Surface salinity has averaged 19.7 ppt, and ranged from 9.7 ppt to 26.3 ppt over the past week. Bottom salinity has averaged 25.4 ppt, ranging 19.3 ppt – 28.8 ppt. Water temperatures have been warming since last week, with surface waters averaging 21.7°C and bottom waters averaging 21.3°C. Hypoxic (dissolved oxygen [DO] <2.9 mg/L) conditions were not observed in surface and bottom waters this week. Surface DO averaged 7.1 mg/L; minimum DO was 4.1 mg/L. Bottom DO was greater than last week, averaging 4.8 mg/L. Bottom DO ranged from 3.0 mg/L to 7.8 mg/L. Chlorophyll was slightly higher this week than last, averaging 33.7 ug/L in surface waters. Note that tidal fluctuations and Blackstone River flow greatly influence water column DO, temperature, and salinity at this location.
Bullock Reach
Good water quality was observed this week at Bullock Reach. The sondes were changed for routine maintenance during the morning of September 24. Water temperatures were slightly warmer than last week, averaging 20.9°C at the surface, 20.6°C at the mid sonde, and 20.1°C at the bottom. Surface salinity averaged 28.5 ppt, ranging from 27.1 ppt to 30.0 ppt. Salinity values at the mid sonde and bottom sondes averaged 29.5 ppt and 30.3 ppt, respectively. Salinity at the surface and mid depths generally increased over the course of the week, while salinity at the bottom depth exhibited a decreasing trend. There were no recorded measurements of hypoxia (DO <2.9 mg/L) at any depths. For the week overall, surface DO averaged 8.4 mg/L with a minimum of 6.5 mg/L, the mid depth averaged 7.3 mg/L with a minimum of 5.7 mg/L, and the bottom had averaged 6.1 mg/L with a minimum of 5.2 mg/L. Surface chlorophyll stayed below 25 ug/L this week, averaging 9.6 ug/L. Chlorophyll at the mid sonde averaged 8.9 ug/L, and chlorophyll at the bottom sonde averaged 8.0 ug/L.
Water Column Clarity
Water clarity was measured at six locations in the Providence and Seekonk Rivers on September 25, 2019. Approximately 0.25 inches of rainfall occurred the day prior to the survey. The average Secchi depth decreased since the last survey, from 1.8 m to 1.5 m. Four sites exhibited decreased clarity since the previous survey, with the greatest decrease observed at Pawtuxet Cove (-0.5 m). The lowest water clarity observed (1.1 m) occurred at Pawtuxet Cove, and the highest water clarity (1.9 m) was observed at Conimicut Point. Two sites, India Point Park and Pomham Rocks, exhibited increased clarity, with an increase of 0.1 m observed at both locations. Overall, a gradient in water clarity was observed in the Upper Bay; water clarity increased from north to south.
