Phillipsdale Landing
Sondes were swapped this week on the morning of October 7th. Overall, the water quality at Phillipsdale Landing was good this week. Weather conditions were fairly dry, with 0.42 inches of rain recorded at T.F. Green. The Blackstone River flow peaked in the middle of the week. Surface salinity averaged 21.0 ppt and ranged from 12.1 ppt–27.2 ppt. At the bottom, salinity averaged 24.3 ppt and ranged from 16.9 ppt–28.6 ppt. Temperatures decreased this week, averaging 19.9°C at the surface and 20.3°C at the bottom. Surface temperatures ranged from 16.5°C–22.8°C, while bottom temperatures ranged from 17.1°C–22.7°C.
Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO>2.9mg/L) in both the surface and bottom waters. Surface DO averaged 5.9 mg/L and ranged from 4.2 mg/L–8.7 mg/L. Bottom DO concentrations averaged 5.5 mg/L and ranged from 4.1 mg/L–8.7 mg/L. Chlorophyll readings decreased from last week, averaging 3.7 µg/L at the surface and 4.7 µg/L at the bottom. Maximum chlorophyll at the surface reached 16.2 µg/L on the morning of October 6th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.
Bullock’s Reach
Overall, water quality was good at Bullock’s Reach this week. Salinity averaged 29.5 ppt, 29.9 ppt, and 30.6 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 27.7–30.9 ppt, mid-depth salinity ranged 28.2–31.0 ppt, and bottom salinity ranged 28.4–31.5 ppt. Surface temperature averaged 19.4°C and ranged from 17.4°C to 21.3°C. Mid-depth temperatures averaged 19.5°C and ranged from 17.8°C to 21.2°C. Bottom temperatures averaged 19.5°C and ranged from 17.9°C to 20.8°C.
Dissolved oxygen (DO) at Bullock’s 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 6.2–9.7 mg/L. In the mid-depth waters, DO averaged 6.9 mg/L and ranged 5.9–8.9 mg/L. At the bottom, DO averaged 6.4 mg/L and ranged 5.2–7.3 mg/L. Chlorophyll concentrations decreased throughout the week. Readings averaged 8.9 µg/L at the surface, 5.4 µg/L at mid-depth, and 6.3 µg/L at the bottom. The maximum surface chlorophyll was 49.3 µg/L on the afternoon of October 6th.