Phillipsdale Landing
Sondes were swapped this week on the morning of October 17th. Overall, water quality at Phillipsdale Landing was good this week. The weather was dry, with no precipitation recorded at T.F. Green. The Blackstone River flow steadily increased through the week, while remaining below the 22-year daily median. Surface salinity averaged 24.2 ppt and ranged from 19.8 ppt to 28.0 ppt. At the bottom, salinity averaged 26.4 ppt and ranged from 22.2 ppt to 29.0 ppt. Temperatures continued to decrease this week, averaging 15.7°C at the surface and ranging 13.0°C – 17.4°C. At the bottom, temperatures averaged 16.1°C and ranged 14.4°C – 17.9°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 8.76 mg/L and ranged from 5.50 mg/L to 13.12 mg/L. Bottom DO concentrations averaged 7.8 mg/L and ranged from 5.4 mg/L to 11.2 mg/L. Chlorophyll readings decreased from last week, averaging 34.33 µg/L at the surface and 23.4 µg/L at the bottom. Maximum chlorophyll at the surface reached 174.50 µg/L on the morning of October 14th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.
Bullock Reach
Overall, the water quality was good at Bullock Reach this week. Salinity averaged 29.0 ppt, 29.6 ppt, and 30.3 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 28.1 – 29.9 ppt, mid salinity ranged 28.7 – 30.3 ppt, and bottom salinity ranged 29.3 – 31.0 ppt. Surface temperature averaged 15.3°C and ranged from 14.0°C to 16.8°C. Mid temperatures averaged 15.3°C and ranged from 14.4°C to 16.8°C. Bottom temperatures averaged 15.3°C and ranged from 14.4°C to 17.0°C.
DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 8.1 mg/L and ranged 7.2 – 9.7 mg/L. In the mid waters, DO averaged 7.9 mg/L and ranged 7.2 – 9.1 mg/L. At the bottom, DO averaged 7.8 mg/L and ranged 7.0– 8.7 mg/L. Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 4.4 µg/L at the surface, 5.2 µg/L at mid-depth, and 6.0 µg/L at the bottom. The maximum surface chlorophyll was 14.9 µg/L on the afternoon of October 20th.