Phillipsdale Landing
Sondes were swapped this week on June 17th. Overall, water quality at Phillipsdale Landing was fair to good this week. Weather conditions were slightly drier than the previous week, with a total of 0.21 inches recorded at T.F. Green, and the majority of rainfall occurring on the 17th. Blackstone River flow remained near the 20-year daily median until the end of the week, when flows declined below the 20-year daily median values. Salinity at the surface averaged 13.1 ppt and ranged from 3.1 ppt to 21.7 ppt. At the bottom, salinity averaged 21.5 ppt and ranged from 3.1 ppt to 27.9 ppt. Temperatures this week averaged 21.1 °C at the surface and 19.0 °C at the bottom. Surface temperatures ranged from 17.7 °C to 25.6 °C, while bottom temperatures ranged from 16.0 °C to 22.4 °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 9.0 mg/L and ranged from 4.4 to 17.1 mg/L. Bottom water DO concentration averaged 5.6 mg/L and ranged from 3.9 mg/L to 10.4 mg/L. Chlorophyll ranged from low to moderate levels throughout the week, averaging 21.4 ug/L at the surface and 17.1 ug/L at the bottom. Maximum surface chlorophyll readings reached 92.1 ug/L on the morning of June 21st. 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 ranged from fair to good at Bullock Reach this week. Salinity averaged 24.7 ppt, 26.8 ppt, and 29.9 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged from 21.5 to 26.6 ppt, mid salinity ranged from 23.6 to 28.7 ppt, and bottom salinity ranged from 27.9 to 31.0 ppt. Surface temperature averaged 20.6 °C and ranged from 18.3 °C to 23.4 °C. Mid temperatures averaged 19.5 °C and ranged from 16.5 °C to 22.7 °C. Bottom temperatures averaged 16.7 °C and ranged from 15.1 °C to 20.1 °C.
DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 9.5 mg/L and ranged from 7.0 to 12.8 mg/L. In the mid waters, DO averaged 7.5 mg/L and ranged from 4.9 to 9.7 mg/L. At the bottom, DO averaged 4.7 mg/L and ranged 3.6 to 6.7mg/L. Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 18.2 µg/L at the surface, 18.2 µg/L at mid-depth, and 6.5 µg/L at the bottom. The maximum surface chlorophyll was 63.8 µg/L on the evening of June 20th.