Phillipsdale Landing
Sondes were swapped this week on the morning of September 30th. Overall, water quality at Phillipsdale Landing was good to fair this week. The weather was dry, with no precipitation recorded at T.F. Green. The Blackstone River flow fluctuated throughout the week, while remaining below the 20-year daily median. Surface salinity averaged 24.6 ppt and ranged from 19.6 ppt to 27.3 ppt. At the bottom, salinity averaged 27.0 ppt and ranged from 23.0 ppt to 28.9 ppt. Temperatures increased this week, averaging 20°C at the surface and ranging 18.4°C – 21.1°C. At the bottom, temperatures averaged 19.9°C and ranged 19.3°C – 21.0°C.
Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 8.3 mg/L and ranged from 4.29 mg/L to 14.02 mg/L. Bottom DO concentrations averaged 6.5 mg/L and ranged from 3.5 mg/L to 10.8 mg/L. Chlorophyll readings increased from last week, averaging 29.57 µg/L at the surface and 19.6 µg/L at the bottom. Maximum chlorophyll at the surface reached 115.3 µg/L on the morning of October 1st. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.
Bullock Reach
Overall, water quality was good at Bullock Reach this week. Salinity averaged 28.9 ppt, 30.4 ppt, and 31.8 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 26.7 – 30.1 ppt, mid salinity ranged 28.8 – 31.5 ppt, and bottom salinity ranged 30.4 – 32.4 ppt. Surface temperature averaged 19.4°C and ranged from 18.5°C to 20.2°C. Mid temperatures averaged 19.3°C and ranged from 18.9°C to 20.0°C. Bottom temperatures averaged 19.1°C and ranged from 18.8°C to 19.6°C.
DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 8.7 mg/L and ranged 6.6 – 12.7 mg/L. In the mid waters, DO averaged 7.4 mg/L and ranged 5.4 – 12.4 mg/L. At the bottom, DO averaged 6.1 mg/L and ranged 5.1 – 9.8 mg/L. Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 14.1 µg/L at the surface, 9.9 µg/L at mid-depth, and 2.6 µg/L at the bottom. The maximum surface chlorophyll was 64.3 µg/L on the afternoon of October 4th.