Walkers Point
Sondes were swapped this week on the morning of June 30th. Overall, the water quality at Walkers Point was good to fair this week. Weather conditions included light rain events this week, with 0.26 inches of precipitation recorded at T.F. Green. Surface salinity averaged 20.6 ppt and ranged from 10.6 ppt to 28.9 ppt. At the bottom, salinity averaged 26.3 ppt and ranged from 24.1 ppt to 29.1 ppt. Temperatures averaged 25.8°C at the surface and 22.5°C at the bottom. Surface temperatures ranged from 22.0°C to 30.1°C, while bottom temperatures ranged from 20.9°C to 24.0°C.
Dissolved oxygen (DO) at Walkers Point dropped below the hypoxia threshold (i.e., DO>2.9mg/L) at both the surface and bottom depths. The longest periods of hypoxic conditions spanned 5 hours, occurring at the bottom depth on the morning of June 29th. During this period, the DO averaged around 2.33 mg/L. Surface DO averaged 10.2 mg/L and ranged from 2.5 mg/L to 24.5 mg/L. Bottom DO concentrations averaged 4.2 mg/L and ranged from 1.9 mg/L to 7.7 mg/L. Chlorophyll readings averaged 21.0 µg/L at the surface and 9.9 µg/L at the bottom. Maximum chlorophyll at the surface reached 195.5 µg/L on the morning of July 1st.
Bullock Reach
Overall, water quality was good to fair at Bullock Reach this week. Salinity averaged 28.3 ppt, 30.2 ppt, and 31.9 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 26.1 – 29.8 ppt, middle salinity range 28.0 – 31.7 ppt, and bottom salinity ranged 30.3 – 32.7 ppt. Surface temperature averaged 25.3°C and ranged from 23.5°C to 27.7°C. Middle temperature averaged 23.7°C and ranged from 21.4°C to 26.4°C. Bottom temperatures averaged 20.7°C and ranged from 18.1°C to 23.9°C.
Dissolved oxygen (DO) at Bullock Reach remained above the hypoxia threshold (i.e., DO>2.9mg/L) at the surface, but dropped below the hypoxia threshold at the middle and bottom depths. The middle depth had a brief drop into hypoxic conditions on the morning of July 4th for two 15-minute intervals. The longest period of hypoxic conditions at the bottom depth spanned 12 hours and 15 minutes, spanning the night of June 29th to the morning of June 30th. During this period, the bottom DO averaged around 2.73 mg/L. Surface DO averaged 7.8 mg/L and ranged 4.4 – 12.8 mg/L. Middle DO averaged 5.9 mg/L and ranged 2.7 – 9.5 mg/L. At the bottom, DO averaged 3.4 mg/L and ranged 2.3 – 6.0 mg/L. Chlorophyll readings ranged from low to elevated throughout the week. Readings averaged 3.2 µg/L at the surface, 15.5 µg/L at the middle, and 12.2 µg/L at the bottom. The maximum bottom chlorophyll was 41.1 µg/L on the morning of July 2nd.