Phillipsdale Landing

Sondes were swapped for routine maintenance on the morning of November 15th. The surface sonde retrieved November 15th had continued buoyancy issues that began the week prior, resulting in approximately 16 hours of data between November 13th and 15th where the sonde was too deep at high tide; these deep data have been excluded from the following summary. Overall, water quality at Phillipsdale Landing was fair to good this week. There was substantial rainfall in the days prior to this week, and the wet weather continued with 0.11 inches on November 13th, 0.13 inches on November 15th, and 0.98 inches on November 16th (all as recorded at T.F. Green). Blackstone River flow remained elevated above the 18-year daily median statistic all week. Salinity at Phillipsdale dropped overall in response to this increase in freshwater flow. Salinity at the surface this week averaged 6.1 ppt and ranged from 2.6 ppt to 10.1 ppt. At the bottom, salinity averaged 21.3 ppt and ranged from 4.1 ppt to 28.5 ppt. Temperatures declined this week, averaging 10.5°C at the surface and ranging 6.5°C – 15.5°C. At the bottom, temperatures averaged 13.9°C and ranged 7.7°C – 16.0°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO this week averaged 9.6 mg/L and ranged 7.4 – 11.6 mg/L. Bottom DO concentrations averaged 6.5 mg/L and ranged from 4.8 mg/L to 10.9 mg/L. Chlorophyll readings were low, averaging 1.4 ug/L at the surface and 1.6 ug/L at the bottom. Maximum chlorophyll at the surface reached 12.4 ug/L on November 13th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. 

Bullock Reach 

Water  quality was good at Bullock Reach this week. Salinity averaged 26.4 ppt, 28.7 ppt, and 30.4 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 22.8 – 28.7 ppt, mid salinity ranged 26.3 – 30.3 ppt, and bottom salinity ranged 29.0 – 31.4 ppt. Temperatures cooled compared to the previous week. Surface temperature averaged 12.9°C and ranged from 10.5°C to 16.0°C. Mid temperatures averaged 13.6°C and ranged from 11.3°C to 15.8°C. Bottom temperatures averaged 14.6°C and ranged from 12.9°C to 15.5°C.

DO concentrations at Bullock Reach remained well above the hypoxia threshold all week. Surface DO averaged 8.2 mg/L and ranged 7.6 – 9.7 mg/L. In the mid waters, DO averaged 7.8 mg/L and ranged 7.1 – 8.9 mg/L. At the bottom, DO averaged 7.3 mg/L and ranged 6.9 – 7.9 mg/L. Chlorophyll concentrations were low all week (i.e., <20 ug/L). Overall, chlorophyll averaged 2.5 ug/L, 2.7 ug/L, and 2.6 ug/L at the surface, mid, and bottom waters, respectively. An isolated spike at the surface up to 52.4 ug/L on November 13th does not appear indicative of phytoplankton bloom activity.