Phillipsdale Landing
Overall, the water quality at Phillipsdale Landing was fair this week. Weather conditions were wet this week, with 0.99 inches of precipitation recorded at T.F. Green. The Blackstone River flow fluctuated throughout the week. Surface salinity averaged 22.2 ppt and ranged from 16.6 ppt to 26.7 ppt. At the bottom, salinity averaged 27.0 ppt and ranged from 18.8 ppt to 30.7 ppt. Surface temperature decreased this week, averaging 23.2°C at the surface and ranging 20.2°C – 25.7°C. The bottom temperature decreased averaged 23.4°C and ranged 21.2°C – 25.7°C.
Dissolved oxygen (DO) at Phillipsdale Landing dropped below the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. The longest periods of hypoxic conditions spanned 8 hours, occurring at the bottom depth on the night of August 19th. During this period, the bottom DO averaged around 2.15 mg/L. Surface DO averaged 7.7 mg/L and ranged from 2.2 mg/L to 15.9 mg/L. Bottom DO concentrations averaged 4.0 mg/L and ranged from 1.0 mg/L to 12.6 mg/L. Chlorophyll readings increased at the surface from last week, averaging 35.5 µg/L and decreased at the bottom, averaging 22.7 µg/L. Maximum chlorophyll at the surface reached 213.3 µg/L on August 21st. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.
Bullock Reach
Sondes were swapped this week on the morning of August 19th. Overall, water quality was good at Bullock Reach this week. Salinity averaged 28.9 ppt, 30.1 ppt, and 31.5 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 27.2– 30.5 ppt, mid salinity ranged 27.8 – 31.5 ppt, and bottom salinity ranged 28.2 – 32.6 ppt. Surface temperature averaged 22.7°C and ranged from 20.9°C to 25.2°C. Mid temperatures averaged 22.6°C and ranged from 21.1°C to 25.2°C. Bottom temperatures averaged 22.1°C and ranged from 20.8°C to 24.5°C.
Dissolved oxygen (DO) at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 7.1 mg/L and ranged 5.5 – 9.4 mg/L. In the mid waters, DO averaged 6.3 mg/L and ranged 4.3 – 8.3 mg/L. At the bottom, DO averaged 5.4 mg/L and ranged 3.6 – 7.8 mg/L. Chlorophyll readings ranged from low to elevated throughout the week. Readings averaged 10.2 µg/L at the surface, 11.8 µg/L at mid-depth, and 8.4 µg/L at the bottom. The maximum surface chlorophyll was 26.7 µg/L on the afternoon of August 18th.