Phillipsdale Landing
The Phillipsdale Landing sondes have been deployed since May 9th, 2023 utilizing a new setup allowing staff access to the equipment from the boat instead of standing on the dock. Sondes were changed out for routine maintenance on June 6th and June 20th.
June was relatively wet, with 3.1 inches of precipitation recorded at T.F. Green. The largest storm occurred on June 17th (1.3 inches). Blackstone River flows were elevated for June 18th (i.e., above the 18-year median statistic of USGS data) in response to the precipitation. Salinity at Phillipsdale averaged 14.0 ppt at the surface (range 1.7 – 26.1 ppt) and 24.4 ppt at the bottom (range 8.3 – 29.5 ppt). Temperatures increased from May, averaging 20.4°C at the surface and 18.0°C at the bottom. Surface temperatures ranged 14.9 – 26.7°C, while bottom temperatures ranged 14.9 – 24.5°C.
The surface dissolved oxygen (DO) concentrations remained above the hypoxia threshold (2.9 mg/L) while the bottom waters were hypoxic periodically throughout the month. The longest sustained period of hypoxic conditions (~13 hours) occurred during the late morning of June 22nd into the early morning of June 23rd. DO averaged 8.3 mg/L at the surface with a minimum of 3.6 mg/L, while bottom waters averaged 3.6 mg/L with a minimum of 0.01 mg/L.
Chlorophyll readings were generally low with periods of moderately elevated chlorophyll intermittently through the month, suggestive of moderate phytoplankton blooms. The surface and bottom readings averaged 20.6 µg/L and 19.8 µg/L, respectively. The maximum surface reading of 86.6 µg/L occurred on June 27th and the maximum bottom reading of 118.2 µg/L occurred on June 7th. Also, please note that data from the bottom sonde between June 23rd and the 29th was excluded due to mud compromising the results. Minor data gaps also occurred periodically between June 11th to the 29th on the surface and bottom due to potential sediment interference (common at this site), fouling, and when the surface sonde was tangled and reporting at an incorrect depth.
Bullock Reach
The Bullock Reach buoy was deployed June 1st for the 2023 season. Sondes were changed out for routine maintenance on June 13th and 27th. Please note that minor data gaps occurred in the surface, middle and bottom on June 1st, 8th, 16th and 27th and is potentially due to equipment failure.
Overall, water quality was good at Bullock Reach Buoy throughout the month of June 2023. Surface, middle, and bottom DO averaged 8.8 mg/L, 7.3 mg/L, and 5.6 mg/L, respectively. Hypoxic conditions were not observed at Bullock Reach this month; the minimum DO observed was 3.1 mg/L measured in bottom waters.
Surface salinity at Bullock Reach ranged 20.6 – 29.1 ppt and averaged 25.9 ppt. Mid-depth salinity ranged 19.7 – 30.5 ppt and averaged 28.1 ppt. Bottom salinity ranged 17.6 – 31.2 ppt and averaged 29.8 ppt. Water column temperatures averaged 19.7°C, 19.0°C, and 17.4°C at the surface, middle, and bottom, respectively. Temperatures ranged 14.6°C – 25.1°C at the surface, 15.2°C – 23.9°C at mid-depth, and 13.6°C – 22.5°C at the bottom. Chlorophyll readings were generally low, averaging 12.2 µg/L at the surface, 11.4 µg/L at mid-depth, and 4.0 µg/L at the bottom. The maximum reading of 38.9 µg/L occurred on June 15th in the surface waters.
Please note that the data exclusions mentioned in the above text for Phillipsdale Landing and Bullock Reach does not affect the raw data, and any exclusions occurred during a QC process, prior to the average, maximum, and minimum calculations discussed.