Phillipsdale Landing
Sondes were swapped this week on the morning of June 25th. Overall, water quality at Phillipsdale Landing was fair this week. Weather conditions included sporadic rain events, with 2.17 inches of precipitation recorded at T.F. Green. The Blackstone River flow fluctuate through the week in response to rain, while still remaining above the 19-year daily median. Surface salinity averaged 9.1 ppt and ranged from 2.6 ppt to 20.3 ppt. At the bottom, salinity averaged 18.6 ppt and ranged from 5.4 ppt to 28.1 ppt. Temperatures continued to increase this week, averaging 25.1°C at the surface and ranging 22.0°C – 27.8°C. At the bottom, temperatures averaged 22.1°C and ranged 19.6°C – 24.7°C.
Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at the surface throughout the week. DO sporadically dropped below the threshold in the bottom waters. Surface DO average 7.44 mg/L and ranged from 3.99 mg/L to 11.35 mg/L. Bottom DO concentrations averaged 4.5 mg/L and ranged from 2.2 mg/L to 10.3 mg/L. Chlorophyll readings dropped slightly from last week, averaging 28.64 µg/L at the surface and 19.9 µg/L at the bottom. Maximum chlorophyll at the surface reached 81.2 µg/L on the morning of June 30th. 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 24.7 ppt, 28.2 ppt, and 27.3 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 20.9 – 27.2 ppt, mid salinity ranged 25.1 – 29.8 ppt, and bottom salinity ranged 23.1 – 30.3 ppt. Surface temperature averaged 22.5°C and ranged from 21.1°C to 25.1°C. Mid temperatures averaged 19.8°C and ranged from 17.8°C to 22.2°C. Bottom temperatures averaged 21.5°C and ranged from 18.5°C to 23.3°C.
DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at all depths throughout the week. Surface DO averaged 7.5 mg/L and ranged 5.3 – 10.9 mg/L. In the mid waters, DO averaged 4.8 mg/L and ranged 3.1 – 6.8 mg/L. At the bottom, DO averaged 6.2 mg/L and ranged 4.3– 8.8 mg/L. Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the month. Readings averaged 17.1 µg/L at the surface, 8.2 µg/L at mid-depth, and 18.3 µg/L at the bottom. The maximum surface chlorophyll was 51.1 µg/L on the afternoon of June 28th.