Phillipsdale Landing
Overall, water quality at Phillipsdale Landing was poor to good this week. Weather conditions were relatively dry this week, with a total of 0.07 inches recorded at T.F. Green, and the majority of rainfall occurring on the 26th. Blackstone River flow decreased slightly over the course of the week, and remained below the 20-year daily median flow. Salinity at the surface averaged 20.6 ppt and ranged from 14.3 ppt to 25.3 ppt. At the bottom, salinity averaged 23.4 ppt and ranged from 4.6 ppt to 27.2 ppt. Temperatures this week averaged 22.3 °C at the surface and 21.4 °C at the bottom. Surface temperatures ranged from 19.8 °C to 26.4 °C, while bottom temperatures ranged from 19.4 °C to 24.6 °C.
Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) for most of the week. Hypoxic conditions were observed at the surface briefly during early morning on June 27th and June 29th. Hypoxic conditions were observed at the bottom for multiple hours in the early morning of June 27th, briefly in the evening of June 28th, and for multiple hours in the evening of June 29th. Surface DO averaged 7.3 mg/L and ranged from 2.8 to 15.1 mg/L. Bottom water DO concentration averaged 5.3 mg/L and ranged from 2.3 mg/L to 12.3 mg/L. Chlorophyll ranged from low to elevated levels throughout the week, averaging 22.2 ug/L at the surface and 16.1 ug/L at the bottom, with evidence of moderate phytoplankton blooms occurring throughout the week. Maximum surface chlorophyll readings reached 92.1 ug/L on the early morning of June 27st. 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 June 24th. Overall, water quality ranged from fair to good at Bullock Reach this week. Salinity averaged 26.1 ppt, 28.4 ppt, and 30.4 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged from 22.2 to 29.1 ppt, mid salinity ranged from 24.9 to 30.6 ppt, and bottom salinity ranged from 28.4 to 31.4 ppt. Surface temperature averaged 22.6 °C and ranged from 20.2 °C to 26.5 °C. Mid temperatures averaged 21.1 °C and ranged from 19.2 °C to 24.6 °C. Bottom temperatures averaged 19.1 °C and ranged from 17.4 °C to 20.6 °C.
DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 7.6 mg/L and ranged from 5.1 to 11.3 mg/L. In the mid waters, DO averaged 6.0 mg/L and ranged from 3.9 to 9.7 mg/L. At the bottom, DO averaged 4.9 mg/L and ranged 3.9 to 6.3 mg/L. Chlorophyll readings ranged from low to moderate, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 10.1 µg/L at the surface, 12.5 µg/L at mid-depth, and 9.8 µg/L at the bottom. The maximum surface chlorophyll was 42.7 µg/L on the afternoon of June 28th.