Walker Point
Overall, water quality at Walker Point was fair to good this week. Weather conditions were somewhat rainy this week, with a total of 0.51 inches recorded at T.F. Green, and the majority of rainfall occurring on the September 28th. Blackstone River flow was highest at the beginning of the week, substantially above the 20-year daily median flow, before decreasing steadily throughout the week, though still remaining above the 20-year daily median flow. Salinity at Walker Point surface averaged 11.8 ppt and ranged from 5.3 ppt to 23.7 ppt. At the bottom, salinity averaged 27.0 ppt and ranged from 18.8 ppt to 30.1 ppt. Temperatures this week averaged 17.7 °C at the surface and 17.9 °C at the bottom. Surface temperatures ranged from 16.1 °C to 20.3°C, while bottom temperatures ranged from 17.2 °C to 18.8 °C.
Dissolved oxygen (DO) at Walker Point remained above the hypoxia threshold at the surface and bottom for the entire week. Surface DO averaged 7.3 mg/L and ranged from 5.6 to 8.9 mg/L. Bottom water DO concentration averaged 5.1 mg/L and ranged from 3.5 mg/L to 6.0 mg/L. Chlorophyll ranged from low to mildly elevated levels throughout the week, averaging 1.5 ug/L at the surface and 0 ug/L at the bottom, with little evidence of any phytoplankton blooms occurring throughout the week. Maximum surface chlorophyll readings reached 15.8 ug/L on the afternoon of October 2nd. 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 September 29th. Overall, water quality was good at Bullock Reach this week. The sonde swap replaced malfunctioning sensors on the bottom sonde, making bottom data available starting on the morning of September 29th. Salinity averaged 24.5 ppt, 29.6 ppt, and 31.4 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged from 19.8 to 28.1 ppt, mid salinity ranged from 23.4 to 31.6 ppt, and bottom salinity ranged from 30.1 to 32.1 ppt. Surface temperature averaged 18.1 °C and ranged from 16.7 °C to 19.9 °C. Mid temperatures averaged 17.9 °C and ranged from 17.5 °C to 19.2 °C. Bottom temperatures averaged 17.8 °C and ranged from 17.5 °C to 18.1 °C.
DO at Bullock Reach did not experience hypoxic conditions (i.e., DO < 2.9 mg/L) during the week. Surface DO averaged 7.5 mg/L and ranged from 6.3 to 8.9 mg/L. In the mid waters, DO averaged 6.6 mg/L and ranged from 5.3 to 7.6 mg/L. At the bottom, DO averaged 6.0 mg/L and ranged from 4.8 to 6.9 mg/L. Chlorophyll readings ranged from low to slightly elevated, with evidence of mild phytoplankton blooms occurring throughout the week. Readings averaged 4.9 µg/L at the surface, 4.1 µg/L at mid-depth, and 3.9 µg/L at the bottom. The maximum surface chlorophyll was 9.9 µg/L on the afternoon of October 1st.