Walker Point
Sondes were swapped this week on October 7th. Overall, water quality at Walker Point was fair to good this week. Weather conditions were rainy this week, with a total of 2.33 inches recorded at T.F. Green, with all rainfall occurring on October 11th. Blackstone River flow decreased throughout the week, staying relatively close to the 20-year daily median flow, before increasingly significantly during the rain event on October 11th. Salinity at Walker Point surface averaged 21.1 ppt and ranged from 11.3 ppt to 28.0 ppt. At the bottom, salinity averaged 27.2 ppt and ranged from 23.1 ppt to 29.4 ppt. Temperatures this week averaged 17.5 °C at the surface and 18.0 °C at the bottom. Surface temperatures ranged from 15.5 °C to 19.0 °C, while bottom temperatures ranged from 17.6 °C to 18.5 °C.
Dissolved oxygen (DO) at Walker Point remained above the hypoxia threshold (2.9 mg/L) at the surface and bottom for the entire week. Surface DO averaged 6.5 mg/L and ranged from 4.2 to 9.0 mg/L. Bottom water DO concentration averaged 4.8 mg/L and ranged from 3.3 mg/L to 6.1 mg/L. Chlorophyll ranged from low to mildly elevated levels throughout the week, averaging 2.9 ug/L at the surface and 3.6 ug/L at the bottom, with little evidence of any phytoplankton blooms occurring throughout the week. Maximum surface chlorophyll readings reached 9.5 ug/L on the afternoon of October 8th. 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 was good at Bullock Reach this week. Salinity averaged 27.9 ppt, 29.7 ppt, and 30.8 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged from 23.0 to 29.5 ppt, mid salinity ranged from 27.8 to 31.4 ppt, and bottom salinity ranged from 28.7 to 32.2 ppt. Surface temperature averaged 17.3 °C and ranged from 16.2 °C to 19.0 °C. Mid temperatures averaged 17.5 °C and ranged from 16.6 °C to 18.5 °C. Bottom temperatures averaged 17.5 °C and ranged from 16.6 °C to 18.3 °C.
DO at Bullock Reach did not experience hypoxic conditions (i.e., DO < 2.9 mg/L) during the week. Surface DO averaged 7.3 mg/L and ranged from 6.2 to 9.0 mg/L. In the mid waters, DO averaged 6.9 mg/L and ranged from 5.1 to 8.6 mg/L. At the bottom, DO averaged 6.6 mg/L and ranged from 5.1 to 7.6 mg/L. Chlorophyll readings remained low, with no evidence of phytoplankton blooms occurring throughout the week. Readings averaged 3.9 µg/L at the surface, 5.8 µg/L at mid-depth, and 5.2 µg/L at the bottom. The maximum surface chlorophyll was 9.5 µg/L on the evening of October 8th.