News – Page 6 – Narrabay

July 30, 2025

Surface chlorophyll data were collected on July 30, 2025, while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuary. The average chlorophyll concentrations were categorized as fair in all individual areas surveyed as well as in the overall survey area. Overall, chlorophyll ranged from 1.1 µg/L to 46.06 µg/L with an average of 10.06 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

July 23, 2025

Surface chlorophyll data were collected on July 23, 2025, while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuary. The average chlorophyll concentrations were categorized as good in the Seekonk River, and as fair in all other areas. The average chlorophyll concentrations were categorized as fair over all areas surveyed. Overall, chlorophyll ranged from 2.85 µg/L to 28.47 µg/L with an average of 7.25 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

July 2, 2025

Surface chlorophyll data were collected on July 2, 2025, while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuary. The average chlorophyll concentrations were categorized as poor in the Seekonk River, and as fair in all other areas. The average chlorophyll concentrations were categorized as fair over all areas surveyed. Overall, chlorophyll ranged from 1.47 µg/L to 145.88 µg/L with an average of 17.45 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

July 30, 2025

Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on July 30, 2025 using a Seabird Electronics profiler. In the five days leading up to the survey, 1.91 inches of precipitation were recorded at T.F. Green. Water column stratification varied between the sites this week from weakly stratified to moderately stratified.

Dissolved oxygen (DO) conditions were below the hypoxia threshold (2.9 mg/L) in the middle portion of the water column at Pomham Rocks, in the middle and lower portions of the water column at India Point Park, Edgewood Yacht Club, Pawtuxet Cove, and Phillipsdale Landing, and in all portions of the water column at Point Street Bridge. The highest fluorescence readings for the week were measured around 1 meter below the surface at Phillipsdale Landing.

July 30, 2025

Water clarity was measured at eight locations in the Providence River and Seekonk River estuaries on July 30, 2025. In the five days prior to the survey, 1.91 inches of precipitation were recorded at TF Green. Secchi depth averaged 2.2 meters. The lowest clarity this week (1.5 meters) was measured at Phillipsdale Landing and Pawtuxet Cove, while the greatest clarity (3.7 meters) was measured at Point Street Bridge. There was no clear north-to-south gradient in water clarity among the sites this week. Overall, water clarity remained approximately the same from the previous measurements (data collected July 23, 2025).

May 26 – June 1, 2025

Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was good this week. Weather conditions were slightly dryer this week than previous weeks, with a total of 0.53 inches recorded at T.F. Green, and the majority of rainfall occurring on the 31^st. The Blackstone River flow decreased throughout the week, but remained above the 20-year daily median for the entire week. Salinity at the surface averaged 4.4 ppt and ranged from 1.4 ppt to 15.6 ppt. At the bottom, salinity averaged 11.1 ppt and ranged from 2.0 ppt to 26.4 ppt. Temperatures this week averaged 17.0 °C at the surface and 16.0 °C at the bottom. Surface temperatures ranged from 13.2 °C to 19.5 °C, while bottom temperatures ranged from 12.6 °C to 19.3 °C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 8.8 mg/L and ranged from 6.8 -10.4 mg/L. Bottom water DO concentration averaged 7.8 mg/L and ranged from 5.5 mg/L to 10.4 mg/L. Chlorophyll was low, averaging 1.5 ug/L at the surface and 1.8 ug/L at the bottom. Maximum surface chlorophyll readings reached 4.4 ug/L in the early morning of May 31^st. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

The Bullock Reach Buoy remains out of the water for the winter. EM will coordinate with RIDEM to redeploy the buoy in late spring-early summer.

May 19 – May 25, 2025

Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was fair to good this week. Weather conditions were wet this week, with a total of 2.31 inches recorded at T.F. Green, and the majority of rainfall occurring on the 26^th. The Blackstone River flow peaked on the 23^rd and 24^th, but remained above the 20-year daily median for the entire week. Salinity at the surface averaged 5.4 ppt and ranged from 0.3 ppt to 12.7 ppt. At the bottom, salinity averaged 12.3 ppt and ranged from 0.1 ppt to 37.2 ppt; however, the salinity data for the first part of the week also exhibits some anomalous behavior, and may be tied to a sensor malfunction. Temperatures this week averaged 14.6 °C at the surface and 13.7 °C at the bottom. Surface temperatures ranged from 12.0 °C to 19.1 °C, while bottom temperatures ranged from 12.2 °C to 18.0 °C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 9.2 mg/L and ranged from 7.1 -11.4 mg/L. Bottom water DO concentration averaged 7.6 mg/L and ranged from 3.4 mg/L to 11.3 mg/L. Chlorophyll was low, averaging 1.1 ug/L at the surface and 1.5 ug/L at the bottom. Maximum surface chlorophyll readings reached 2.4 ug/L. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

The bottom sonde had a malfunctioning depth sensor, thus no depth data is available for the bottom sonde until the sondes were swapped out on May 20^th.

Bullock Reach

The Bullock Reach Buoy remains out of the water for the winter. EM will coordinate with RIDEM to redeploy the buoy in late spring-early summer.

May 12 – May 18, 2025

Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was fair to good this week. Weather conditions were wet this week, with a total of 1.38 inches recorded at T.F. Green, and the majority of rainfall occurring on the 15^th. The Blackstone River flow peaked on the 16^th and remained above the 20-year daily median for the entire week. Salinity at the surface averaged 1.8 ppt and ranged from 0.4 ppt to 4.2 ppt. At the bottom, salinity averaged 9.1 ppt and ranged from 0.0 ppt to 32.8 ppt; however, the salinity data for the first part of the week also exhibits some anomalous behavior, and may be tied to a sensor malfunction. Temperatures this week averaged 18.2 °C at the surface and 16.1 °C at the bottom. Surface temperatures ranged from 14.7 °C to 20.6 °C, while bottom temperatures ranged from 11.8 °C to 20.1 °C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 9.0 mg/L and ranged from 7.8 -10.4 mg/L. Bottom water DO concentration averaged 7.1 mg/L and ranged from 3.9 mg/L to 9.9 mg/L. Chlorophyll was low, averaging 0.9 ug/L at the surface and 2.7 ug/L at the bottom. Maximum surface chlorophyll readings reached 3.7 ug/L, recorded on the afternoon of May 12^th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

The bottom sonde had a malfunctioning depth sensor this week, thus no depth data is available for the bottom sonde. The salinity data for this week also exhibits some anomalous behavior, and may have been malfunctioning.

Bullock Reach

The Bullock Reach Buoy remains out of the water for the winter. EM will coordinate with RIDEM to redeploy the buoy in late spring-early summer.

May 5- May 11, 2025

Phillipsdale Landing

The Phillipsdale Landing sondes were deployed for the season on May 6, 2025. Overall, water quality at Phillipsdale Landing was fair to good this week. Weather conditions were wet this week, with a total of 3.51 inches recorded at T.F. Green, and the majority of rainfall occurring on the 5^th, 6^th, and 9^th. The Blackstone River flow increased on the 5^th and remained above the 20-year daily median for the remainder of the week. Salinity at the surface averaged 2.2 ppt and ranged from 0.5 ppt to 6.2 ppt. At the bottom, salinity averaged 11.3 ppt and ranged from 0.0 ppt to 28.4 ppt. Temperatures this week averaged 16.9 °C at the surface and 15.0 °C at the bottom. Surface temperatures ranged from 14.2 °C to 19.6 °C, while bottom temperatures ranged from 11.8 °C to 18.3 °C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 9.3 mg/L and ranged from 7.9 -10.6 mg/L. Bottom water DO concentration averaged 7.1 mg/L and ranged from 3.9 mg/L to 10.3 mg/L. Chlorophyll was low, averaging 2.11 ug/L at the surface and 4.5 ug/L at the bottom. Maximum surface chlorophyll readings reached 20.8 ug/L, recorded on the morning of May 6^th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

The bottom sonde had a malfunctioning depth sensor this week, thus no depth data is available for the bottom sonde.

Bullock Reach

The Bullock Reach Buoy remains out of the water for the winter. EM will coordinate with RIDEM to redeploy the buoy in late spring-early summer.

July 23, 2025

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on July 23, 2025. In the five days prior to the survey, trace amounts of precipitation were recorded at TF Green. Secchi depth averaged 2.0 meters. The lowest clarity this week (1.7 meters) was measured at Edgewood Yacht Club and Pomham Rocks, while the greatest clarity (2.5 meters) was measured at Bullock’s Reach. There was no clear north-to-south gradient in water clarity among the sites this week. Overall, water clarity remained approximately the same from the previous measurements (data collected July 16, 2025).