Historical News
Water Column Clarity
Water clarity was measured at eight locations in the Providence and Seekonk Rivers on July 26, 2017. A total of 0.56 inches of rainfall was recorded two days prior, however most of the previous week had been dry. Overall, clarity showed a marked increase compared to the previous survey, with Secchi depth averaging 2.7 meters versus 1.3 m the week before. The maximum water clarity (3.3 m) was observed at India Point Park; the minimum water clarity (2.1 m) was observed at Phillipsdale Landing. Each individual site exhibited substantially increased clarity compared to the previous survey, ranging from a 0.87 m increase at Phillipsdale, to a 1.85 m increase at Point St. Bridge.
Bacteria Sampling
Eighteen stations were sampled for fecal coliform bacteria in the Providence and Seekonk River estuary on July 26, 2017. Seven of these stations were also sampled for Enterococci bacteria. A total of 0.56 inches of rain fell during the five days prior to sampling; bacteria counts were slightly elevated throughout the estuary.
Overall, the fecal coliform geometric mean among all sites was 104 MPN/100 mL, a substantial decrease compared to the previous sampling date. Fecal coliform concentrations in the Seekonk River had a geometric mean of 97 MPN/100 mL, while results from the Providence River had a geometric mean of 107 MPN/100 mL. The maximum fecal coliform concentration of 430 MPN/100 mL was observed at the Point St. Bridge and South FP East locations, both in the Providence River. Overall, neither the Providence nor Seekonk River sites met state criteria for primary contact or shellfishing.
Enterococci concentrations ranged from less than detection (10 MPN/100 mL) at South FP East, Save the Bay, Gaspee Point, and Conimicut Point to 97 MPN/100 mL at Division St. Dock. The overall geometric mean for Enterococci was 15 MPN/100 mL. These results do not meet state criteria 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.
Surface Mapping
Data was collected on July 28, 2017 while the R/V Monitor was underway conducting buoy maintenance in the Providence River estuary. The chlorophyll concentrations were fair in areas surveyed with evidence of a north-south gradient. From north to south, average chlorophyll concentrations were as follows: Upper Providence River (5.58 µg/l), Edgewood Shoals area (9.24 µg/l), Pawtuxet River area (14.19 µg/l), and the Lower Providence River (14.52 µg/l). Overall, chlorophyll ranged between 2.1 and 23.6 µg/l with an overall average of 11.15 µg/l. The chlorophyll data from this date is presented in the map below:
Fixed Site Network
Phillipsdale
At Phillipsdale, sonde data revealed fair to poor water quality conditions over the course of the week. There only trace amounts of rainfall recorded for the week. Surface and bottom salinities responded to this lack of rain/freshwater input by steadily increasing throughout the week. Surface salinity began the week mainly below 8 psu, but increased to an average of about 14 psu at weeks end, the overall average was 7.6 psu and ranged from 1.4psu – 22.5 psu. Bottom salinity was affected by tidal fluctuations, though to a lesser degree by the end of the week, and had an average salinity of 18.8 psu and a range of 5.3 psu – 25.9 psu. Both surface and bottom temperatures increased from last week with surface temperature average of 24oC and a range of 21.1oC – 28.6oC; bottom temperatures had an average of 22.6oC and ranged between 20.0oC – 25.1oC. Some stratification was evident between surface and bottom at the beginning of the week. Surface chlorophyll increased throughout the week, though there were several erroneous values reported from the sonde; overall chlorophyll averaged of 7.3ug/L. Dissolved oxygen (DO) for the week was fair to good at the surface and was nearly hypoxic the entire week at the bottom. The surface had some readings of DO below 2.9 mg/L, but overall had an average of 5.4 mg/L and ranged from 1.6 mg/l to 9.8 mg/L. Dissolved oxygen in the bottom waters had a weekly average of 2.3 mg/l and ranged from a minimum of 1.1 mg/L to a maximum of 5.8 mg/L. Rolling and daily averages of bottom DO showed nearly constant hypoxic conditions this week, except for some early morning/late evening increases in DO. Note that tidal fluctuations greatly influence bottom DO, temperature and salinity at this location.
Bullocks Reach
Water quality at Bullocks Reach was fair this week. Bottom waters at Bullocks Reach were much colder and more saline that surface waters, indicating some stratification may have been present. Mid data was only available for this summary from 7/20 – 7/22. Surface water temperatures averaged 24.3oC, mid temperatures averaged 21.5oC, and bottom temperatures had average temperature of 19.8oC. Surface, mid and bottom salinities averaged 23.2 psu, 28.3 psu, and 29.1 psu, respectively. Surface dissolved oxygen (DO) decreased over the course of the week and was quite variable with a minimum of 2.1 mg/L and a maximum of 13.2 mg/L, with an average of 5.8 mg/L for the week. The two days of available mid DO data showed fair conditions with an average of 3.1 mg/L. Bottom DO was steady over the course of the week, but was below the hypoxic threshold of 2.9 mg/L for much of the week. Rolling and daily averages of bottom DO showed nearly constant hypoxic conditions this week, except for some early morning/late evening increases in DO; the weekly average for bottom DO was 2.6 mg/L with a range of 1.9 mg/L – 5.0 mg/L. Surface chlorophyll increased throughout the week and averaged 10.7 ug/L.
R/V Monitor's Blog
The R/V Monitor was out on the upper Bay twice this week. First, on Tuesday, July 25th, the crew performed sonde changeouts at the Bullock's Reach buoy. An adjustment to the mid-level sonde depth was also made. Jeff captained the boat while monitoring professionals Sara and Bekki performed the buoy work. The weather was cool, damp and dreary with a wind from the north. The water was relatively calm with a mild chop. On Wednesday, July 26th, the crew of the R/V Monitor was out on the upper Bay collecting bacteria samples, taking Secchi Disk and Par sensor water clarity measurements, conducting water column profiles using the Seabird instrument, 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. A brief stop at the NBC's Bullock's Reach buoy was made to adjust a sonde. Jeff captained the boat while monitoring professionals Steve and Amanda collected the samples and data. NBC summer intern Louisa also assisted with sampling and data collection duties. It was a warm and sunny day with low humidity. The water was extra calm this day. Sailors in training were observed in the photo below enjoying the fine weather on the upper Bay this day.
