Historical News
Fixed Site Network
Water quality at Phillipsdale Landing was good this week. Conditions were relatively dry, with only 0.5 inches of rainfall occurring on December 12. Surface salinity continued to remain low, following the heavy rainfall that occurred the previous week. However, surface salinity generally increased over the course of the week, and averaged 3.5 ppt, with a range of 0.3 ppt to 12.6 ppt. Bottom salinity averaged 14.9 ppt, and ranged from 0.5 ppt at the beginning of the week to 31.5 ppt towards the end of the week.
Surface temperatures were colder than those measured the previous week, averaging 4.7°C and ranging from 2.0°C to 6.7°C. Bottom temperatures also cooled, averaging 6.7°C and ranging from 3.7°C to 10.0°C. Dissolved oxygen (DO) remained above the hypoxia threshold (2.9 mg/L) in surface and bottom waters this week. Surface DO averaged 12.5 mg/L, with a minimum of 10.5 mg/L, while bottom DO averaged 10.3 mg/L, with a minimum of 7.6 mg/L. Chlorophyll concentrations averaged 2.8 ug/L at the surface and 2.0 ug/L at the bottom. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and dissolved oxygen at this location.
Bullock Reach
The Bullock Reach sondes were removed for the 2020 monitoring season on November 17.
Nutrients Sampling
Nutrient samples were collected from seven local river stations on December 16. Due to adverse weather concerns, bay nutrient sampling was not collected as scheduled. In the three days prior to sampling there was 0.25 inches of rainfall recorded at T.F. Green.
Among the river stations samples, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were all observed at Ten Mile River at Central Avenue. At this site, concentrations for TN, TDN, and DIN were 2,300 ppb, 2,470 ppb, and 1,936.9 ppb, respectively. The lowest TN (738 ppb) and TDN (597 ppb) results were observed at Palmer River at Route 6, while the lowest DIN (225 ppb) result was observed at Coles River at Milford Road.
Results from nutrients sampling on December 30 and January 13 are pending analysis. The next scheduled date of sampling is January 27, 2021.
Nutrients Sampling
Nutrient samples were collected from the surface and bottom waters at seven bay stations on December 2. Nutrient samples were also collected at seven local river stations. In the three days prior to sampling there was 3.45 inches of rainfall recorded at T.F. Green.
Among the river stations samples, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were all observed at Ten Mile River at Roger Williams Avenue. At this site, concentrations for TN, TDN, and DIN were 1,410 ppb, 1,320 ppb, and 920.4 ppb, respectively. The lowest TN (787 ppb) and TDN (713 ppb) results were observed at Moshassuck River at Footbridge at Mill Street, while the lowest DIN (380.6 ppb) result was observed at Moshassuck River at Higginson Avenue.
Among the bay stations sampled, the highest TN (1,310 ppb), TDN (1,070 ppb), and DIN (765 ppb) in surface waters was observed at India Point Park. The lowest surface TN (773 ppb), TDN (611 ppb), and DIN (414 ppb) were all observed at Conimicut Point Park. Chlorophyll a concentrations averaged 1.15 ug/L, with a maximum result of 1.63 ug/L occurring at India Point Park.
Results from nutrients sampling on December 16 and 30 are pending analysis. The next scheduled date of sampling is January 13, 2021.
Fixed Site Network
Water quality at Phillipsdale Landing was good this week, despite the heavy precipitation. Precipitation totaled 6.11 inches at TF Green, with a majority of the rainfall occurring on November 30 (2.74 inches) and December 5 (2.65 inches). In response to the rainfall, an increase in freshwater input from the Blackstone River occurred, which resulted in a decrease in salinity at both depths over the course of the week. Salinity at the surface averaged 5.5 ppt and ranged from 0.3 ppt to 33.8 ppt. Salinity in bottom waters averaged 14.2 ppt and ranged from 0.3 ppt to 29.1 ppt. Surface temperatures were slightly warmer than those observed the previous week, averaging 9.0 °C and ranging from 5.9°C to 12.2°C. Bottom temperature averaged 9.8°C and ranged from 6.5°C to 11.7°C.
Dissolved oxygen (DO) remained above the hypoxia threshold (2.9 mg/L) in surface and bottom waters this week. Surface DO averaged 10.4 mg/L, with a minimum of 7.8 mg/L, while bottom DO averaged 9.0 mg/L, with a minimum of 6.8 mg/L. Chlorophyll concentrations continued to be low through the week, averaging 2.5 ug/L at the surface and 1.7 ug/L at the bottom. Maximum surface chlorophyll concentrations reached 5.4 ug/L on December 2. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and dissolved oxygen at this location.
Bullock Reach
The Bullock Reach sondes were removed for the 2020 monitoring season on November 17.
Water Column Profiles
Water column profiles were measured at three locations in the Providence River using the Seabird profiling instrument on November 18, 2020. A water column profile was also conducted at one site in the Seekonk River, Phillipsdale Landing, using a YSI EXO sonde. However, settings on the YSI EXO sonde were not optimized for measurements of a true profile, rather, the goal was to obtain stable estimates of conditions at the surface and bottom only. Data from all measurements are summarized here, and raw data from the YSI EXO profile are available upon request. In the five days prior to sampling, precipitation totaled 0.65 inches at TF Green. Stratification was observed at Edgewood Yacht Club, Edgewood Shoal, and Phillipsdale Landing.
Water column salinity was highest at Edgewood Yacht Club, with measurements in surface and bottom waters of 26 psu and 29 psu, respectively. Salinity was lowest at Phillipsdale Landing, measuring approximately 15 psu in surface waters and 26 psu in bottom waters. In surface waters, temperatures ranged from 9.5°C at Phillipsdale Landing to 11.3°C at Pawtuxet Cove. Temperatures in bottom waters ranged from 11.1°C at Pawtuxet Cove to 11.9°C at Phillipsdale Landing.
Dissolved oxygen (DO) ranged from a minimum of 7.2 mg/L below the pycnocline at Edgewood Shoal to 9.3 mg/L in surface waters at Phillipsdale Landing. 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.
