Phillipsdale Landing
Overall, water quality at Phillipsdale Landing was good this week. Weather conditions included sporadic rain events, with 0.83 inches of precipitation recorded at T.F. Green. The Blackstone River flow fluctuate through the week in response to sporadic rain events. salinity averaged 13.9 ppt and ranged from 2.9 ppt to 22.8 ppt. At the bottom, salinity averaged 21.1 ppt and ranged from 7.2 ppt to 28.2 ppt. Temperatures continued to increase this week, averaging 25.6°C at the surface and ranging 23.3°C – 28.5°C. At the bottom, temperatures averaged 22.3°C and ranged 19.7°C – 24.5°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 8.7 mg/L and ranged from 3.4 mg/L to 18.4 mg/L. Bottom DO concentrations averaged 5.2 mg/L and ranged from 2.8 mg/L to 11.1 mg/L. The longest period of hypoxic conditions (1 hour) occurred in the afternoon of July 2nd. During this period, bottom DO averaged around 2.84 mg/L. Chlorophyll readings rose from last week, averaging 63.5 µg/L at the surface and 33.4 µg/L at the bottom. Maximum chlorophyll at the surface reached 125.4 µg/L on the night of July 4th. 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 the morning of July 2nd. Overall, water quality was good at Bullock Reach this week. Salinity averaged 24.5 ppt, 26.7 ppt, and 28.8 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 20.8 – 26.6 ppt, mid salinity ranged 22.8 – 30.3 ppt, and bottom salinity ranged 26.9 – 30.5 ppt. Surface temperature averaged 22.9°C and ranged from 21.2°C to 25.3°C. Mid temperatures averaged 22.0°C and ranged from 18.7°C to 23.8°C. Bottom temperatures averaged 20.0°C and ranged from 17.8°C to 23.0°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 4.8 – 12.5 mg/L. In the mid waters, DO averaged 6.3 mg/L and ranged 4.1 – 8.4 mg/L. At the bottom, DO averaged 4.7 mg/L and ranged 3.3 – 6.9 mg/L. Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 16.3 µg/L at the surface, 13.0 µg/L at mid-depth, and 4.9 µg/L at the bottom. The maximum surface chlorophyll was 48.3 µg/L on the afternoon of July 2nd.