Historical News

Week of October 24 – 30, 2021

Fixed Site Network

Phillipsdale Landing

Water quality at Phillipsdale Landing was good this week. Precipitation totaled 3.21 inches at TF Green for the week, with over 1 inch of precipitation occurring on October 26th (1.04 in) and October 30th (1.40 in). Blackstone River flows remained elevated over historical median values. Surface salinity decreased over the course of the week and ranged from 1.5 ppt to 17.6 ppt. Surface salinity was lower than the previous week, averaging 7.9 ppt. Bottom salinity ranged 2.9 ppt – 29.6 ppt and averaged 19.5 ppt. Water temperatures also decreased over the course of the week and averaged 14.5°C on the surface and 16.4°C on the bottom. Surface temperatures ranged from 12.1°C to 17.7°C while bottom temperatures ranged from 12.4°C to 18.8°C.

At both depths, dissolved oxygen (DO) increased over the course of the week. Surface DO averaged 8.8 mg/L, with a minimum of 6.0 mg/L. Bottom DO averaged 6.5 mg/L, with a minimum of 4.5 mg/L. Hypoxic conditions (DO ≤ 2.9 mg/L) were not observed at Phillipsdale Landing this week. Chlorophyll concentrations averaged 2.5 µg/L on the surface and 1.6 µg/L on the bottom, with a maximum of 6.9 µg/L observed in bottom waters. Please 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 good this week. Surface salinity decreased over the course of the week in response to the rainfall. Surface salinity ranged from 20.6 ppt to 28.9 ppt and averaged 25.6 ppt. Salinity at mid-depth ranged from 25.6 ppt to 31.0 ppt and averaged 29.0 ppt. Bottom salinity ranged from 27.1 ppt to 31.4 ppt and averaged 30.4 ppt. Water column temperatures continued to cool this week, averaging 16.1°C, 16.9°C, and 17.2°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 13.9°C to 18.1°C, mid temperatures ranged from 15.5°C to 18.3°C, and bottom temperatures ranged from 16.2°C to 18.2°C.

This week, DO averaged 7.4 mg/L at the surface, 6.9 mg/L at mid-depth, and 6.6 mg/L at the bottom. Waters at all depths remained above the hypoxia threshold, with minimum bottom DO measuring 5.6 mg/L. Chlorophyll concentrations were lower than the previous week, averaging 0.7 µg/L at the surface, 0.6 µg/L at mid-depth, and 1.3 µg/L at the bottom. Chlorophyll concentrations were greatest at the beginning of the week, with a maximum value of 11.2 µg/L occurring in the bottom waters.

Week of October 17 – 23, 2021

Fixed Site Network

Phillipsdale Landing

Water quality at Phillipsdale Landing was good this week. Sondes were changed out for routine maintenance on October 19th. Precipitation totaled 0.18 inches at TF Green for the week. Water column salinity increased from the previous week, averaging 9.4 ppt on the surface and 22.1 ppt on the bottom. Surface salinity ranged from 2.1 ppt to 18.7 ppt, while bottom salinity ranged from 5.1 ppt to 28.7 ppt. Water temperatures averaged 17.6°C on the surface and 19.1°C on the bottom. Surface temperatures ranged from 14.0°C to 19.5°C while bottom temperatures ranged from 17.6°C to 20.2°C.

Surface dissolved oxygen (DO) averaged 7.7 mg/L, with a minimum value of 5.8 mg/L. Bottom DO averaged 5.3 mg/L, with a minimum of 3.6 mg/L. Hypoxic conditions (DO ≤ 2.9 mg/L) were not observed at Phillipsdale Landing this week. Chlorophyll concentrations averaged 2.1 µg/L on the surface and 1.5 µg/L on the bottom, with a maximum of 13.1 µg/L observed in bottom waters. Please 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 good this week. Surface salinity ranged from 23.1 ppt to 28.5 ppt and averaged 26.3 ppt. Salinity at mid-depth ranged from 26.2 ppt to 29.8 ppt and averaged 28.4 ppt. Bottom salinity ranged from 27.3 ppt to 30.3 ppt and averaged 29.2 ppt. Water temperatures were cooler than the previous week, averaging 18.5°C, 18.6°C, and 18.7°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 16.6°C to 20.3°C, mid-depth temperatures ranged from 17.4°C to 20.3°C, and bottom temperatures ranged from 17.8°C to 20.2°C.

This week, DO averaged 7.7 mg/L at the surface, 7.2 mg/L at mid-depth, and 6.7 mg/L at the bottom. Waters at all depths remained above the hypoxia threshold, with minimum bottom DO measuring 5.9 mg/L. Chlorophyll concentrations were lower than the previous week, averaging 3.5 µg/L at the surface, 2.4 µg/L at mid-depth, and 2.9 µg/L at the bottom. Some evidence of phytoplankton bloom activity was observed, with values > 25 µg/L observed at all three depths.

Week of October 10 – 16, 2021

Fixed Site Network

Phillipsdale Landing

Water quality at Phillipsdale Landing was fair this week. Rainfall was light, totaling 0.16 inches at TF Green. Water column salinity increased from the previous week, averaging 8.1 ppt on the surface and 21.9 ppt on the bottom. Surface salinity ranged from 2.7 ppt to 17.7 ppt, while bottom salinity ranged from 3.6 ppt to 28.7 ppt. Water temperatures were warmer than the previous week, averaging 18.6°C on the surface and 17.9°C on the bottom. Surface temperatures ranged from 16.7°C to 20.2°C, while bottom temperatures ranged from 17.9°C to 20.2°C.

Surface dissolved oxygen (DO) averaged 7.5 mg/L, with a minimum of 5.1 mg/L. Bottom DO averaged 3.8 mg/L, with a minimum of 2.4 mg/L. Hypoxic conditions (DO ≤ 2.9 mg/L) were observed intermittently in bottom waters throughout the week. The longest duration of sustained bottom hypoxia (2.5 hours) occurred on October 15th. Chlorophyll concentrations were lower than the previous week, averaging 1.8 µg/L on the surface and 1.1 µg/L on the bottom, with a surface maximum of 8.9 µg/L. Please 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 good this week. Sondes were changed out for routine maintenance on October 13th. Surface salinity averaged 25.5 ppt, mid salinity averaged 29.5 ppt, and bottom salinity averaged 30.7 ppt. Surface salinity ranged from 21.4 ppt to 28.8 ppt, mid salinity ranged from 25.6 ppt to 31.7 ppt, while bottom salinity ranged from 27.4 ppt to 32.7 ppt. Water temperatures averaged 19.5°C, 19.3°C, and 19.2°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 17.8°C to 20.9°C, mid temperatures ranged from 18.6°C to 20.3°C, and bottom temperatures ranged from 19.0°C to 20.1°C.

Concentrations of DO were higher than the previous week, averaging 9.0 mg/L at the surface, 7.1 mg/L at mid-depth, and 6.0 mg/L at the bottom. Waters at all depths remained above the hypoxia threshold, with minimum bottom DO measuring 4.9 mg/L. Chlorophyll concentrations were greater than the previous week, averaging 11.1 µg/L at the surface, 9.0 µg/L at mid-depth, and 6.3 µg/L at the bottom. Evidence of phytoplankton bloom activity was observed throughout the week, and values > 75 µg/L occurred at all three depths.

Week of October 3 – 9, 2021

Fixed Site Network

Phillipsdale Landing

Water quality at Phillipsdale Landing was fair this week. Sondes were changed out for routine maintenance on October 5th. Rainfall totaled 1.67 inches at TF Green for the week, with the majority of this precipitation (1.5 in) occurring on October 4th. Blackstone River flow continued to remain elevated above historical median values. Water column salinity decreased in response to the heavy rainfall on October 4th, reaching minimum values of 0.7 ppt and 1.4 ppt on the surface and bottom, respectively. Surface salinity averaged 7.1 ppt for the week, while bottom salinity averaged 19.2 ppt. Water temperatures cooled in comparison to the previous week, averaging 17.9°C on the surface and 19.2°C on the bottom. Surface temperatures ranged from 15.6°C to 20.4°C, while bottom temperatures ranged from 15.9°C to 20.8°C.

Surface dissolved oxygen (DO) averaged 7.8 mg/L, with a minimum of 3.9 mg/L. Bottom DO averaged 5.1 mg/L, with a minimum of 2.4 mg/L. Hypoxic conditions (DO ≤ 2.9 mg/L) at the bottom improved compared to the previous week, with the longest duration of sustained hypoxia (2 hours) occurring on October 3rd. Chlorophyll concentrations decreased over the course of the week, averaging 3.1 µg/L on the surface and 2.3 µg/L on the bottom, with a surface maximum of 17.6 µg/L. Please 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 good this week. Surface salinity declined in response to the heavy rainfall event on October 4th and ranged from 19.3 ppt to 29.7 ppt. Surface salinity averaged 24.7 ppt, mid salinity averaged 30.5 ppt, and bottom salinity averaged 32.4 ppt. Mid salinity ranged from 25.7 ppt to 32.5 ppt, while bottom salinity ranged from 31.1 ppt to 34.0 ppt. Water temperatures continued to cool, averaging 19.4°C, 19.5°C, and 19.6°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 17.8°C to 20.4°C, mid temperatures ranged from 19.0°C to 20.3°C, and bottom temperatures ranged from 19.2°C to 20.5°C.

Concentrations of DO were higher than the previous week, averaging 7.3 mg/L at the surface, 6.2 mg/L at mid-depth, and 5.1 mg/L at the bottom. Waters at all depths remained above the hypoxia threshold, with minimum bottom DO measuring 4.1 mg/L. Chlorophyll concentrations averaged 4.4 µg/L at the surface, 4.2 µg/L at mid-depth, and 3.7 µg/L at the bottom. Evidence of phytoplankton bloom activity occurred from October 3rd – 4th and October 7th – 9th, and chlorophyll values of approximately ≥ 25 µg/L occurred at all three depths.

Week of July 25 - 31, 2021

Water Column Profiles

​Water column profiles were conducted at six locations in the Providence River using a Seabird profiling instrument on July 28, 2021. Conditions leading up to the survey included light rainfall recorded at T.F. Green over the five days prior, totaling 0.24 inches. 

The lowest salinities this week were observed at Pawtuxet Cove, ranging from 16 psu at the surface to 24 psu at the bottom. The highest salinities in surface waters were observed at India Point Park and Edgewood Yacht Club, at 23 psu; the highest bottom salinities (30 psu) were observed at Bullock Reach and Conimicut Point. Surface temperatures ranged from 22.5°C at Pomham Rocks to 23.4°C at Conimicut Point and Bullock Reach. Bottom temperatures were coolest (~20°C) at Conimicut Point and warmest (~23°C) at Pawtuxet Cove. 

Dissolved oxygen (DO) concentrations were low this week, with hypoxic conditions (e.g., DO <2.9 mg/L) observed at almost all sites. The only site with DO levels remaining above this threshold was Conimicut Point, where DO ranged 3.5-6.2 mg/L, with the highest values near the surface. The site with the lowest DO was Pawtuxet Cove, where hypoxic conditions were observed in the bottom 1 m, reaching a minimum of 1.4 mg/L. Maximum fluorescence this week was observed in near-surface waters at Conimicut Point. Please note that due to a quality control issue, numerical fluorescence data are not posted at this time.

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