Historical News
Bacteria Sampling
On March 31, twenty stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers. Five of these stations were also sampled for enterococci bacteria. Precipitation in the five days prior to sampling totaled 1.53 inches, with a majority of the rainfall (1.47 inches) occurring on March 28.
The geometric mean of fecal coliform results for all sites was 31 MPN/100 mL, with Seekonk River sites having higher counts than Providence River sites (geometric means of 116 and 16 MPN/100 mL, respectively). The maximum count (230 MPN/100 mL) was measured at both Phillipsdale Landing and Crook Point in the Seekonk River. Overall, fecal coliform results from the Seekonk River exceeded both state shellfishing and primary contact standards. Fecal coliform results from the Providence River also exceed state shellfishing standards, but results were within state primary contact standards for the Providence River.
Enterococci results increased slightly from the previous sampling event, from an overall geometric mean of 12 MPN/100 mL to 16 MPN/100 mL. Enterococci results at all sites ranged from <10 MPN/100 mL at three stations (South FP East, Gaspee Point, and Conimicut Point) to 63 MPN/100 mL at Phillipsdale Landing. Overall, enterococci results were within state primary contact standards for both rivers.
Please note: the results of NBC's fecal coliform and enterococci monitoring are for informational/research purposes only and are not to intended to suggest official state compliance with bathing or shellfishing standards.
Water Column Profiles
Surface salinities among the sites surveyed ranged from 21 psu at Pomham Rocks to 27 psu at Edgewood Yacht Club. Bottom salinities measured approximately 30 psu at all sites. Surface water temperatures ranged from 3°C at Conimicut Point to 3.5°C at the remaining sites. Bottom temperatures ranged from 3°C at most sites to 4°C at Edgewood Yacht Club.
Dissolved oxygen (DO) ranged from a minimum of approximately 11 mg/L in bottom waters at all sites to 12.1 mg/L in surface waters at Conimicut Point. Hypoxic conditions (e.g., DO concentrations <2.9 mg/L) were not observed at any of the sites. Please note that due to a quality control issue, numerical fluorescence data are not posted at this time.
Water Column Clarity
Water clarity was measured at four locations in the Providence River on February 24, 2021; the survey day was cut short due to mechanical problems on the boat. Moderate rainfall totaling 0.81 inches was recorded in the area over the five days prior to the survey, and snowmelt also occurred over that time. Overall, Secchi depth averaged 4.04 meters, compared to 3.13 meters on January 13, 2021. The lowest clarity (3.63 meters) was measured at Bullock Reach, while the greatest clarity (4.25 meters) was measured at Pomham Rocks. Generally, water clarity was higher at the northernmost sites (Pomham Rocks and Edgewood Yacht Club) than the southern sites (Bullock Reach and Conimicut Point) this week.
Water Column Profiles
R/V Monitor's Blog
On Wednesday, March 31st, 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, 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. The crew conducted side by side profile tests using the new YSI EXO2 sonde and the YSI 6 Series sonde. Sara captained the boat while monitoring professionals Daryll, Justin, and Rebecca collected the samples and data. It was a cloudy day with a southwest wind and a slight chop on the water. The photo taken this day was of the Conimicut lighthouse.
