Phillipsdale Landing
Overall, the water quality at Phillipsdale Landing was fair this week. Weather conditions were dry, with no precipitation recorded at T.F. Green. The Blackstone River flow fluctuated throughout the week. Surface salinity averaged 18.3 ppt and ranged from 6.8 ppt to 26.1 ppt. At the bottom, salinity averaged 25.1 ppt and ranged from 14.7 ppt to 28.7 ppt. Surface temperature increased this week, averaging 24.2°C at the surface and ranging 22.5°C – 26.5°C. The bottom temperature increased averaged 23.2°C and ranged 21.9°C – 25.0°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 21.75 hours, occurring at the bottom depth from the afternoon of August 6th until the morning of August 7th. During this period, the bottom DO averaged around 1.69 mg/L. Surface DO averaged 9.1 mg/L and ranged from 1.9 mg/L to 22.2 mg/L. Bottom DO concentrations averaged 3.4 mg/L and ranged from 0.0 mg/L to 12.0 mg/L. Chlorophyll readings increased from last week, averaging 30.1 µg/L at the surface and 33.1 µg/L at the bottom. Maximum chlorophyll at the surface reached 349.2 µg/L on the morning of August 5th. 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 5th. Overall, water quality was good to fair at Bullock Reach this week. Salinity averaged 27.8 ppt, 29.6 ppt, and 31.1 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 24.3– 29.6 ppt, mid salinity ranged 27.5 – 30.9 ppt, and bottom salinity ranged 29.5 – 32.1 ppt. Surface temperature averaged 23.6°C and ranged from 22.5°C to 25.0°C. Mid temperatures averaged 22.9°C and ranged from 21.0°C to 24.0°C. Bottom temperatures averaged 21.1°C and ranged from 19.7°C to 23.3°C.
Dissolved oxygen (DO) at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at the surface and middle depths throughout the week, while DO at the bottom waters dropped below the hypoxic threshold at the start of the week. Surface DO averaged 8.3 mg/L and ranged 5.9 – 11.9 mg/L. In the mid waters, DO averaged 6.2 mg/L and ranged 3.1 – 8.8 mg/L. At the bottom, DO averaged 3.4 mg/L and ranged 1.9 – 6.8 mg/L. Chlorophyll readings ranged from low to elevated throughout the week. Readings averaged 14.4 µg/L at the surface, 9.8 µg/L at mid-depth, and 4.4 µg/L at the bottom. The maximum surface chlorophyll was 33.4 µg/L on the afternoon of August 5th.