Historical News

Week of July 19 - 25, 2020

Fixed Site Network

Phillipsdale Landing
Sondes were swapped out for maintenance on the morning of July 21. The surface sonde was periodically hung-up on old pilings from July 22 through 25, coming out of water for several hours at a time; data from these periods have been excluded from the summary below. 

Water quality was poor to fair this week at Phillipsdale Landing. The weather was mostly dry and salinities increased as the week progressed. Surface salinity averaged 15.9 ppt (range 1.4 – 24.6 ppt), while bottom salinity averaged 22.8 ppt (range 15.6 – 27.0 ppt). Water temperatures warmed since last week; surface temperatures ranged from 24.3°C to 29.3°C and averaged 26.3°C, while bottom temperatures ranged from 23.7°C to 26.9°C and averaged 25.5°C. Dissolved oxygen (DO) concentrations were hypoxic (<2.9 mg/L) in both surface and bottom waters for a substantial portion of the week. Surface waters averaged 6.7 mg/L with a minimum of 0.7 mg/L; surface hypoxia occurred primarily during early-morning low tides. Bottom DO averaged 2.8 mg/L with a minimum of 0.1 mg/L; bottom waters were hypoxic for 60% of the week. Surface chlorophyll was similar this week compared to last, averaging 38.9 ug/L with evidence of phytoplankton bloom activity throughout the week. Note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Water quality at Bullock Reach was fair this week. Surface salinity averaged 27.0 ppt, ranging 24.0 - 28.6 ppt. Salinity values at the mid and bottom sondes averaged 28.3 ppt and 29.8 ppt, respectively. Water temperatures continue to warm, averaging 26.1°C at the surface, 25.2°C at the mid depth, and 23.2°C at the bottom. Surface and mid waters remained above the hypoxia threshold this week, with DO minima of 5.2 mg/L and 3.3 mg/L, respectively; hypoxia was observed in bottom waters, averaging 3.8 mg/L with a minimum of 2.7 mg/L. Bottom hypoxia occurred primarily on July 23, for short durations up to 45 minutes at a time. Chlorophyll was similar this week to last, averaging 14.4 ug/L at the surface and reaching a maximum of 27.7 ug/L; mid-depth chlorophyll averaged 10.0 ug/L and bottom chlorophyll averaged 6.9 ug/L.

Week of July 12 - 18, 2020

Fixed Site Network

Phillipsdale Landing

Water quality was poor this week at Phillipsdale Landing. There was rainfall recorded at TF Green on two days this week (0.82 inches July 14; 0.14 inches July 17); salinity at Phillipsdale declined toward the end of the week in response to this rainfall. Surface salinity averaged 12.2 ppt (range 1.2 – 19.6 ppt), while bottom salinity averaged 23.1 ppt (range 14.2 – 28.7 ppt). Water temperatures warmed since last week; surface temperatures ranged from 21.7°C to 28.9°C and averaged 25.4°C, while bottom temperatures ranged from 21.9°C to 26.2°C and averaged 24.1°C. Dissolved oxygen (DO) concentrations were hypoxic (<2.9 mg/L) in both surface and bottom waters for a substantial portion of the week. Surface waters averaged 6.8 mg/L with a minimum of 0.2 mg/L; surface hypoxia occurred primarily during early-morning low tides, for durations up to three hours. Bottom DO was extremely hypoxic or anoxic, averaging 0.7 mg/L with a minimum of 0.1 mg/L; bottom waters were hypoxic for 97% of the week. Surface chlorophyll was slightly lower this week than last, averaging 30.4 ug/L; evidence of phytoplankton bloom activity was strongest on July 12, with smaller peaks into the midweek. Note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Sondes were swapped out for maintenance on the morning of July 14. The bottom sonde retrieved that day had exhibited excessive drift in specific conductivity and salinity data beginning the previous week; bottom salinity data from this sonde have been excluded from the following summary. 

Water quality at Bullock Reach was fair this week. Rainfall on July 14 resulted in increased Pawtuxet River flows near this site, and surface salinities reflected an influx of freshwater. Surface salinity averaged 25.7 ppt, ranging 21.9 - 28.1 ppt. Salinity values at the mid and bottom sondes averaged 28.3 ppt and 30.4 ppt, respectively. Water temperatures continue to warm, averaging 25.1°C at the surface, 24.3°C at the mid depth, and 22.5°C at the bottom. Surface waters remained above the hypoxia threshold this week, with a DO minimum of 7.1 mg/L; hypoxia was observed in both mid and bottom depths, with DO minima of 2.0 mg/L and 2.1 mg/L, respectively. Hypoxia at the mid-depth occurred primarily from July 15 to 16, for up to nine hours at a time; hypoxia at the bottom occurred primarily on June 16 and 17, for up to five hours at a time. Please note, calculation of DO in mg/L utilizes information from the salinity probe; as a result of the drift in the salinity probe, bottom DO readings may be overestimated during this reporting period. Chlorophyll declined slightly this week, averaging 12.7 ug/L at the surface and reaching a maximum of 28.9 ug/L; mid-depth chlorophyll averaged 22.0 ug/L and bottom chlorophyll averaged 5.3 ug/L.

Week of July 5 - 11, 2020

Fixed Site Network

Phillipsdale Landing

Phillipsdale sondes were changed out for maintenance on the morning of July 7. The newly deployed bottom sonde depth readings were erroneous for the first several hours of deployment; the sensor functionality was restored later that day. 

Water quality was poor to fair this week at Phillipsdale Landing. There was very little rain over the course of the week, less than 0.1 inch, and salinity generally increased compared to the previous week. Surface salinity averaged 14.4 ppt (range 2.5 - 22.3 ppt), while bottom salinity averaged 21.4 ppt (range 11.7 – 26.2 ppt). Water temperatures warmed since last week; surface temperatures ranged from 22.1°C to 27.9°C and averaged 24.7°C, while bottom temperatures ranged from 21.4°C to 26.0°C and averaged 23.6°C. Dissolved oxygen (DO) concentrations dipped below the hypoxia threshold (2.9 mg/L) in both surface and bottom waters this week. Surface waters averaged 7.3 mg/L with a minimum of 1.3 mg/L; surface hypoxia occurred during early-morning low tides, for up to two hours at a time. Bottom DO averaged 2.6 mg/L with a minimum of 0.1 mg/L; bottom waters were hypoxic for 67% of the week. Lastly, surface chlorophyll averaged 47.4 ug/L this week, evidence of phytoplankton bloom activity peaking on the 7th, 8th, and 11th. Note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Note that the bottom sonde began to exhibit excessive drift in specific conductivity and salinity data beginning in the evening of July 9; bottom salinity data from this time through the rest of the week have been excluded from the following summary. 

Water quality at Bullock Reach was fair this week. Water temperatures continue to warm, averaging 24.2°C at the surface, 23.4°C at the mid depth, and 21.8°C at the bottom. Surface salinity averaged 26.8 ppt, ranging 24.4 - 28.7 ppt, slightly higher than the previous week. Salinity values at the mid and bottom sondes averaged 28.3 ppt and 31.8 ppt, respectively. Surface and mid-depth waters remained above the hypoxia threshold this week, with DO minima of 5.0 mg/L and 3.2 mg/L, respectively. Bottom water DO averaged 4.1 mg/L, with a minimum reading of 2.8 mg/L; hypoxia lasted for approximately two hours on July 6th. Please note, calculation of DO in mg/L utilizes information from the salinity probe; as a result of the drift in the salinity probe, bottom DO readings may be overestimated during this reporting period. Chlorophyll was slightly elevated this week, averaging 15.8 ug/L at the surface and reaching a maximum of 38.6 ug/L; mid-depth chlorophyll averaged 17.5 ug/L and bottom chlorophyll averaged 5.6 ug/L.

Week of June 28 - July 4, 2020

Fixed Site Network

Phillipsdale Landing

Water quality was poor to fair this week at Phillipsdale Landing. Heavy rainfall at the end of last week caused surface salinity to drop substantially as Blackstone River flows increased. Bottom salinity was also reduced; note that approximately 12 hours of problematic bottom salinity data on June 28 were excluded from this summary. 

Surface salinity averaged 9.2 ppt (range 3.0 - 23.3 ppt), while bottom salinity averaged 19.8 ppt (range 6.0 - 28.4 ppt). Water temperatures cooled slightly from the previous week; surface temperatures averaged 23.4°C and bottom temperatures averaged 22.2°C. Surface temperatures ranged from 21.2°C to 26.8°C, while bottom temperatures ranged from 20.1°C to 25.1°C. Dissolved oxygen (DO) concentrations were fair at the surface and poor in bottom waters most of the week. Surface waters remained above the hypoxia threshold of 2.9 mg/L, averaging 7.4 mg/L with a minimum of 3.3 mg/L. Bottom DO averaged 3.0 mg/L with a minimum of 0.2 mg/L; bottom waters were hypoxic for approximately 58% of the week. Please note, calculation of DO in mg/L utilizes information from the salinity probe; the problematic salinity data on June 28th were so far out of range that the DO data have also been excluded for that period prior to summarizing here. Surface chlorophyll averaged 29.0 ug/L this week with evidence for phytoplankton bloom activity, particularly on June 29th. Note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Bullock Reach sondes were changed-out for maintenance on the morning of June 30. The mid-depth sonde retrieved on June 30 had recorded erroneous depth readings; though there are no precise depth data for the deployment period (June 16-June 30), the position of the sonde in the water was good and all other parameters recorded normally. The bottom sonde retrieved on June 30 exhibited excessive drift in specific conductivity and salinity toward the end of the deployment; bottom salinity data from June 28 through 10am on June 30 have been excluded from the following summary. 

Water quality at Bullock Reach was fair to good this week. Water temperatures continue to warm, averaging 23.5°C at the surface, 22.2°C at the mid depth, and 20.1°C at the bottom. Surface salinity averaged 24.8 ppt, ranging from 20.8 ppt to 28.0 ppt. Salinity values at the mid and bottom sondes averaged 28.7 ppt and 32.5 ppt, respectively. Salinity at the surface decreased over the course of the week, impacted by river runoff following rains the previous week. Mid and bottom waters remained just above the hypoxia threshold this week, reaching DO minima of 2.9 mg/L and 3.0 mg/L, respectively. Average DO for surface, mid, and bottom waters was 7.0 mg/L, 4.9 mg/L, and 4.1 mg/L, respectively. Please note, calculation of DO in mg/L utilizes information from the salinity probe; as a result of the drift in the salinity probe, bottom DO readings may be overestimated during this reporting period. Chlorophyll was slightly elevated this week, particularly at the surface, averaging 16.4 ug/L and reaching a maximum of 56.4 ug/L; mid-depth chlorophyll averaged 10.3 ug/L and bottom chlorophyll averaged 3.6 ug/L.

Week of July 19 – 25, 2020

Water Column Clarity

​Water clarity was measured at six locations in the Providence and Seekonk Rivers on July 22, 2020. Within the five days prior to the survey, 0.16 inches of precipitation was recorded. On the morning of the survey, 0.06 inches of precipitation occurred. Average Secchi depth increased by 0.17 m since the last survey, from 1.54 m to 1.70 m. The greatest increase in water clarity was observed at Phillipsdale Landing, which increased by 1.13 m, from 0.83 m to 1.97 m. Water clarity also exhibited increases at Pomham Rocks, Bullock Reach, and Conimicut Point. Water clarity decreased at Edgewood Yacht Club (-0.40 m). The greatest water clarity was observed at Phillipsdale Landing, which had a measured Secchi depth of 1.97 m. Lowest water clarity was observed at Edgewood Yacht Club, with a measured Secchi depth of 1.43 m. Generally, water clarity decreased along a north-to-south gradient in the Upper Bay.

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