Snapshot of the Bay

Historical News

Week of May 29 - June 4, 2022

Water Column Profiles

Water column profiles were conducted at eight locations in the Providence and Seekonk River using a Seabird profiling instrument on June 1, 2022. Conditions leading up to the survey were dry, with just trace precipitation recorded at T.F. Green over the three days prior. Evidence of density stratification was observed at all sites.

Surface salinities ranged from 20 psu at India Point Park to 27 psu at Edgewood Yacht Club. Bottom salinities ranged from 26 psu at Phillipsdale Landing to 31 psu at Conimicut Point. The warmest water temperatures were observed at Pawtuxet Cove, ranging from 20.6°C at the surface down to 19.5°C at the bottom. The coolest surface water temperatures (~18.7°C) were observed at Phillipsdale Landing, while the coolest bottom temperatures (~15.3°C) were observed at India Point Park.

Dissolved oxygen (DO) conditions remain above the hypoxia threshold (2.9 mg/L) at all sites. The minimum DO concentration observed this week was 3.5 mg/L in the deepest two meters of water at Edgewood Shoal. Fluorescence remained slightly elevated this week, the highest values (~12 mg/m³) were observed in near surface waters at India Point Park. Please note: numerical fluorescence data were not posted from 2020 to 2021 due to a QC issue. This issue has been resolved and fluorescence data from 2020 and 2021 will be back-filled.

Week of May 15 - 21, 2022

Nutrients Sampling

Nutrient samples were collected from fourteen local and border river stations and seven bay stations on May 18, 2022. Bay stations were sampled at the surface and bottom. Very little rainfall was recorded over the five days prior to sampling, less than 0.1 inches, as recorded at T.F. Green.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were all observed at the Ten Mile River at Central Ave. At this site, average of duplicate samples measured 1,705 ppb TN, 1,725 ppb TDN, and 1,352 ppb DIN. The lowest concentrations of TN (522 ppb) and TDN (496 ppb) occurred at the Moshassuck River at Higginson Ave., while the lowest concentration of DIN (49 ppb) occurred at the Warren Reservoir/Kickemuit River.

Among the bay stations sampled, the highest surface nitrogen concentrations occurred at Pawtuxet Cove. Duplicate surface sample concentrations at this site averaged 1,110 ppb TN, 1,015 ppb TDN, and 801 ppb DIN. The lowest nitrogen concentrations were measured at several sites. TN was lowest at Conimicut Point (337 ppb) and Bullock Reach (336 ppb). TDN was lowest at Conimicut Point (145 ppb). DIN was lowest (13 ppb) at Conimicut Point, Bullock Reach, and Edgewood Yacht Club. Surface chlorophyll a concentrations were low, averaging 4.0 ug/L with a maximum of 5.4 ug/L measured at Conimicut Point.

Results from nutrient sampling on June 1 and June 15 are pending analysis. The next scheduled sample date is June 29.

Week of May 1 - 7, 2022

Nutrients Sampling

Nutrient samples were collected from seven local river stations and eight bay stations on May 4, 2022. Most bay stations were sampled at the surface only; one station, Edgewood Shoal, was sampled at the surface and bottom. Moderate rainfall of 0.5 inches was recorded at T.F. Green two days prior to sampling and 0.14 inches was recorded during the day of sampling itself.

Among the river stations sampled, the highest surface total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were all observed at the Pawtuxet River at Broad St. At this site, average of duplicate surface samples measured 1,255 ppb TN, 1,230 ppb TDN, and 996 ppb DIN. The lowest nitrogen concentrations occurred at the Moshassuck River at Higginson Ave. at 464 ppb TN, 561 ppb TDN, and 229 ppb DIN.

Among the bay stations sampled, the highest surface nitrogen concentrations were again measured near the Pawtuxet River, at the Pawtuxet Cove site. Concentrations at this site were 1,080 ppb TN, 1,000 ppb TDN, and 759 ppb DIN. The lowest TN concentration (423 ppb) was measured at Bullock Reach Buoy, while the lowest TDN (211 ppb) and DIN (50 ppb) were measured at Conimicut Point. Surface chlorophyll a concentrations were generally low, averaging 5.6 ug/L with a maximum of 12.0 ug/L measured at Phillipsdale Landing.

Results from nutrient sampling on May 18 are pending analysis. The next scheduled sample date is June 1.

Week of June 12 – 18, 2022

Fixed Site Network

Phillipsdale Landing

Sondes were swapped for routine maintenance on the morning of June 14. Overall, water quality at Phillipsdale Landing was fair to good this week. Weather conditions this week were mostly wet, with 1.57 inches of rainfall recorded at T.F. Green. A majority of the rainfall (1.31 inches) occurred on June 13, resulting in Blackstone River flows declining over the course of the week and remaining below historical 16-year median flow rates. Surface salinity averaged 17.7 ppt and ranged from 5.5 ppt to 26.5 ppt, while bottom salinity averaged 23.4 ppt and ranged from 13.7 ppt to 28.1 ppt. Temperatures continue to warm, averaging 21.6°C at the surface and 20.8°C on the bottom. Surface temperatures ranged from 19.8°C to 24.9°C, while bottom temperatures ranged from 19.6°C to 22.7°C.

Dissolved oxygen (DO) remained above the hypoxia threshold (2.9 mg/L) for most of the week. Surface DO averaged 6.3 mg/L with a minimum of 3.0 mg/L, while bottom DO averaged 4.6 mg/L, with a minimum of 2.2 mg/L. A maximum duration of hypoxia of approximately four hours occurred during late night on June 11. Chlorophyll readings this week were similar to the previous week, averaging 16.1 µg/L on the surface and 13.3 µg/L on the bottom. Maximum surface chlorophyll readings reached 70.5 µg/L. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Overall, water quality at Bullock Reach was good this week. Surface salinity ranged from 23.3 ppt to 30.0 ppt and averaged 27.2 ppt. Salinity at mid-depth ranged from 25.6 ppt to 30.4 ppt and averaged 28.7 ppt. Bottom salinity ranged from 28.9 ppt to 31.1 ppt and averaged 30.2 ppt. Water column temperatures averaged 21.2°C, 20.4°C, and 19.3°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 19.9°C to 23.1°C, mid temperatures ranged from 18.9°C to 21.6°C, and bottom temperatures ranged from 17.8°C to 20.7°C.

This week, DO averaged 7.9 mg/L at the surface, 6.8 mg/L at mid-depth, and 5.3 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 were low, averaging 12.2 µg/L at the surface, 11.2 µg/L at mid-depth, and 3.9 µg/L at the bottom. The maximum chlorophyll this week was 41.4 µg/L measured in surface waters on June 15.

Week of June 05 – 11, 2022

Fixed Site Network

Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was fair this week. A total of 1.81 inches of rainfall was recorded at T.F. Green on June 08 and 09, which led to increased flows from the Blackstone River in the middle of the week. Following the influx of freshwater in the middle of the week, salinity decreased at Phillipsdale Landing as the week progressed. Surface salinity averaged 11.9 ppt and ranged from 4.0 ppt to 21.0 ppt, while bottom salinity averaged 22.5 ppt and ranged from 8.3 ppt to 28.2 ppt. Temperatures continue to warm, averaging 21.7°C at the surface and 19.8°C on the bottom. Surface temperatures ranged from 19.0°C to 24.7°C, while bottom temperatures ranged from 17.6°C to 22.4°C.

Dissolved oxygen (DO) concentrations decreased through the week but remained mostly above the hypoxia threshold (2.9 mg/L). Surface DO averaged 8.2 mg/L with a minimum of 3.3 mg/L, while bottom DO averaged 4.2 mg/L, with a minimum of 1.6 mg/L. Chlorophyll readings decreased from the previous week, averaging 15.8 µg/L on the surface and 12.7 µg/L on the bottom. Maximum surface chlorophyll readings reached 80.5 µg/L. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Sondes were swapped for routine maintenance at mid-day on June 08. Please note that there is an extra hour's worth of data included in the summary below caused by updating the timestamps of the sondes to local eastern standard time. Also note that portions of chlorophyll data from the mid-depth sonde from June 08 – 11 are not included in the summary below due to an issue with the chlorophyll sensor. Overall, water quality at Bullock Reach was good this week. Surface salinity ranged from 24.3 ppt to 28.8 ppt and averaged 26.9 ppt. Salinity at mid-depth ranged from 26.4 ppt to 30.2 ppt and averaged 28.8 ppt. Bottom salinity ranged from 29.1 ppt to 32.3 ppt and averaged 30.8 ppt. Water column temperatures averaged 20.5°C, 19.6°C, and 18.0°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 18.4°C to 22.5°C, mid temperatures ranged from 17.9°C to 21.2°C, and bottom temperatures ranged from 15.9°C to 19.8°C.

This week, DO averaged 8.2 mg/L at the surface, 6.8 mg/L at mid-depth, and 5.3 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 were low, averaging 8.0 µg/L at the surface, 6.0 µg/L at mid-depth, and 3.0 µg/L at the bottom. The maximum chlorophyll this week was 36.2 µg/L measured in surface waters on June 11.