Historical News
Week of October 2 - 8, 2022
Fixed Site Network
Phillipsdale Landing
Sondes were swapped for routine maintenance during the morning on October 4th. Overall, water quality at Phillipsdale Landing was good this week. Weather conditions were moderately wet, with 1.28 inches of rainfall recorded at T.F. Green. The Blackstone River flow increased above the 17-year median flow rate towards the end of the week. Salinity at the surface averaged 21.0 ppt and ranged from 8.9 ppt – 26.3 ppt. At the bottom, salinity averaged 26.0 ppt and ranged from 19.3 ppt – 29.8 ppt. Temperatures cooled this week, averaging 16.6°C at the surface and 17.1°C at the bottom. Surface temperatures ranged from 15.1°C to 19.5°C, while bottom temperatures ranged from 15.4°C to 18.9°C.
Dissolved oxygen (DO) has increased at Phillipsdale Landing, with the surface and bottom waters above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Bottom water DO concentration averaged 5.7 mg/L and ranged from 3.8 mg/L to 7.0 mg/L. Surface DO was higher, averaging 6.5 mg/L and ranging 4.7 – 8.3 mg/L. Chlorophyll concentrations were low, averaging 2.8 ug/L at the surface and 2.3 ug/L at the bottom. Maximum surface chlorophyll readings reached just 7.5 ug/L, recorded on the morning of October 2nd and afternoon on October 7th. 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 was good at Bullock Reach this week. Salinity averaged 29.0 ppt, 29.9 ppt, and 31.4 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 26.3 – 30.2 ppt, mid salinity ranged 28.4 – 31.4 ppt, and bottom salinity ranged 29.4 – 32.3 ppt. Temperatures decreased from the previous week. Surface temperature averaged 16.8°C and ranged from 15.8°C to 18.0°C. Mid temperatures averaged 16.8°C and ranged from 16.2°C to 18.1°C. Bottom temperatures averaged 16.9°C and ranged from 16.2°C to 18.6°C.
DO concentrations at Bullock Reach remained above the hypoxia threshold all week. Surface DO averaged 7.4 mg/L and ranged 6.2 – 8.9 mg/L. In the mid waters, DO averaged 7.3 mg/L and ranged 6.2 – 8.3 mg/L. At the bottom, DO averaged 7.0 mg/L and ranged 5.7– 7.5 mg/L. Chlorophyll concentrations were low all week. Overall, chlorophyll averaged 3.0 ug/L, 4.0 ug/L, and 1.8 ug/L at the surface, mid, and bottom waters, respectively. The maximum surface chlorophyll reading was 6.2 ug/L on October 7th.
Week of September 18 - 24, 2022
Nutrients Sampling
Nutrient samples were collected from eight bay stations and seven local river stations on September 21, 2022. Most bay stations were sampled at the surface only; one station, Edgewood Shoal, was sampled at the surface and bottom. Very little rain preceded this sampling event, with T.F. Green recording just 0.08 inches over the five days prior.
Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) occurred at Blackstone River at Slater Mill, measuring 2,090 ppb, 1,950 ppb, and 1,687 ppb, respectively. The lowest TN, TDN, and DIN were observed at Moshassuck River at Higginson Ave., measuring 904 ppb, 628 ppb, and 474 ppb, respectively.
Among the bay stations sampled, the highest surface TN (1,650 ppb) occurred at Phillipsdale Landing. TDN and DIN were highest at Pawtuxet Cove, measuring 1,260 ppb and 870 ppb, respectively. The lowest surface TN (775 ppb) occurred at Bullock Reach Buoy. TDN and DIN were lowest at Edgewood Shoal, measuring 251 ppb and 49.7 ppb, respectively. Chlorophyll a concentrations at the bay stations increased from the previous sampling event, averaging 28.2 ug/L across all sites (average of previous sampling event was 2.2 ug/L). The maximum results were observed at India Point Park (70.9 ug/L).
Results from nutrient sampling on October 5th, and October 19th are pending analysis. The next scheduled sample date is November 2nd.
Week of September 4 - 10, 2022
Nutrients Sampling
Nutrient samples were collected from seven bay stations and thirteen local and border river stations on September 7, 2022. Bay stations were sampled at the surface and bottom. Heavy rains preceded this sampling event, with T.F. Green recording 3.77 inches over the two days prior.
Among the river stations sampled, the highest total nitrogen (TN) occurred at Blackstone River at Slater Mill; duplicate samples collected from this site averaged 1,675 ppb. Total dissolved nitrogen (TDN) was highest at Blackstone River at Bikepath Bridge (1,370 ppb); one of the duplicate samples from the Blackstone River at Slater Mill was similarly high at 1,370 ppb, however the other duplicate was lower at 1,300 ppb. The highest dissolved inorganic nitrogen (DIN) was also observed at Blackstone River at Bikepath Bridge (1,019 ppb). The lowest TN and TDN were observed at Woonasquatucket River at Valley St., measuring 672 ppb and 629 ppb, respectively. DIN was lowest at Runnins River at River Rd, measuring 233 ppb.
Among the bay stations sampled, the highest surface nitrogen concentrations were observed at Phillipsdale Landing. The TN, TDN, and DIN were 1,790 ppb, 1,350 ppb, and 980 ppb, respectively. The lowest surface nitrogen concentrations were observed at Pomham Rocks. The TN, TDN, and DIN were 791 ppb, 528 ppb, and 292.7 ppb, respectively. Chlorophyll a concentrations at the bay stations decreased from the previous sampling event, averaging 2.2 ug/L across all sites (average of previous sampling event was 16.5 ug/L). The maximum results were observed at Conimicut Point (2.77 ug/L) and Bullock Reach (2.72 ug/L, average of duplicates).
Results from nutrient sampling on September 21st, October 5th, and October 19th are pending analysis. The next scheduled sample date is November 2nd.
Week of September 25 - October 1, 2022
Fixed Site Network
Phillipsdale Landing
Communication problems persisted at this station during this week; live-data updates to Snapshot are still not functioning but data are being added to the Snapshot website periodically via manual upload. Overall, water quality conditions at Phillipsdale Landing were moderate this week. T.F. Green recorded 0.9 inches of rainfall, mainly on October 1st (0.6 inches). Blackstone River flows declined all week, though remain elevated above 17-year median flows overall. Salinity at the surface increased this week, averaging 19.1 ppt and ranging 9.2 ppt – 25.9 ppt. At the bottom, salinity was similar to the prior week, averaging 24.4 ppt and ranging 15.5 ppt – 29.0 ppt. Temperatures declined compared to the previous week, averaging 19.2°C at the surface and 19.8°C at the bottom. Surface temperatures ranged from 17.2°C to 20.6°C, while bottom temperatures ranged from 18.0°C to 20.7°C.
Dissolved oxygen (DO) improved this week at Phillipsdale Landing, with the bottom waters generally remaining above the hypoxia threshold (i.e., DO >2.9 mg/L). Bottom water DO concentration averaged 4.0 mg/L and ranged from 2.3 mg/L to 6.7 mg/L. The longest duration of hypoxic conditions at the bottom was approximately 2 hours on September 25-26th. Surface DO was higher, averaging 5.2 mg/L and ranging 3.1 – 8.1 mg/L. Chlorophyll concentrations were generally low this week, averaging 3.7 ug/L at the surface and 4.7 ug/L at the bottom. Maximum surface chlorophyll readings reached 17.0 ug/L on October 1st. 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 maintenance during the morning of September 27th. Overall water quality was good at Bullock Reach this week. Salinity averaged 28.0 ppt, 29.4 ppt, and 30.8 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 25.3 – 29.4 ppt, mid salinity ranged 27.1 – 31.2 ppt, and bottom salinity ranged 29.3 – 32.2 ppt. Please note there was a low salinity spike in the mid-depth data at the beginning of the week; these salinity data plus DO (mg/L) and depth data during the spike were also excluded. Temperatures decreased from the previous week. Surface temperature averaged 18.9°C and ranged from 17.7°C to 20.2°C. Mid temperatures also averaged 18.9°C and ranged from 17.9°C to 19.6°C. Bottom temperatures averaged 19.1°C and ranged from 18.3°C to 19.4°C.
DO concentrations at Bullock Reach remained above the hypoxia threshold this week. Surface DO averaged 6.9 mg/L and ranged 5.9 – 8.8 mg/L. In the mid waters, DO averaged 6.7 mg/L and ranged 5.8 – 8.5 mg/L. At the bottom, DO averaged 6.1 mg/L and ranged 5.4 – 7.5 mg/L. Chlorophyll readings were generally low this week. Surface chlorophyll averaged 5.9 ug/L and reached a maximum of 16.8 ug/L on September 25th. At the mid-depth, chlorophyll averaged 6.0 ug/L and reached a maximum of 19.1 ug/L September 27th. Chlorophyll was lowest at the bottom, averaging 3.2 ug/L with a maximum of 10.5 ug/L on September 27th.
Week of September 18 - 24, 2022
Fixed Site Network
Phillipsdale Landing
Communication problems persisted at this station during this week; live-data updates to Snapshot are still not functioning but data are being added to the Snapshot website periodically via manual upload. Sondes were swapped for maintenance during the morning of September 20th. Overall, water quality conditions at Phillipsdale Landing were poor to moderate this week. T.F. Green recorded 1.20 inches of rainfall, mainly on September 22nd (1.12 inches). Blackstone River flows increased all week and salinity declined accordingly. Salinity at the surface averaged 15.6 ppt and ranged 6.4 ppt – 23.2 ppt. At the bottom, salinity averaged 25.3 ppt and ranged 14.1 ppt – 29.6 ppt. Temperatures also declined compared to the previous week, averaging 21.0°C at the surface and 21.7°C at the bottom. Surface temperatures ranged from 16.1°C to 23.7°C, while bottom temperatures ranged from 18.4°C to 22.6°C.
Dissolved oxygen (DO) remains low at Phillipsdale Landing, with the bottom waters frequently below the hypoxia threshold (i.e., DO <2.9 mg/L). Bottom water DO concentration averaged 2.9 mg/L and ranged from 0.6 mg/L to 7.1 mg/L. The longest duration of hypoxic conditions at the bottom was approximately 19 hours from September 21st into September 22nd. Surface DO was higher, averaging 9.0 mg/L and ranging 3.4 – 18.0 mg/L. The elevated surface DO was due to a phytoplankton bloom occurring during the first half of the week. Chlorophyll concentrations were elevated into Thursday, when the heavy rain event seemed to flush these conditions away (the rains appear to have also helped to break-up the stratification at this site, and bottom DO recovered slightly after this point). For the week, chlorophyll averaged 51.6 ug/L at the surface and 10.0 ug/L at the bottom. Maximum surface chlorophyll readings reached 179.5 ug/L on September 19th. 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 was good at Bullock Reach this week. Salinity averaged 28.3 ppt, 30.4 ppt, and 31.1 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 26.4 – 29.7 ppt, mid salinity ranged 27.8 – 31.7 ppt, and bottom salinity ranged 28.8 – 32.4 ppt. Please note there were some low salinity spikes in the mid-depth data late this week that were excluded from this summary; DO (mg/L) and depth data during these spikes were also excluded. Temperatures decreased from the previous week. Surface temperature averaged 21.1°C and ranged from 18.7°C to 22.7°C. Mid temperatures averaged 21.2°C and ranged from 18.8°C to 22.4°C. Bottom temperatures averaged 21.0°C and ranged from 18.9°C to 21.9°C.
DO concentrations at Bullock Reach remained above the hypoxia threshold this week. Surface DO averaged 7.2 mg/L and ranged 5.2 – 11.4 mg/L. In the mid waters, DO averaged 6.0 mg/L and ranged 4.1 – 8.7 mg/L. At the bottom, DO averaged 4.8 mg/L and ranged 3.4 – 6.5 mg/L. Like Phillipsdale, DO concentrations at Bullock Reach this week were higher in part due to active phytoplankton bloom activity. Chlorophyll readings were slightly elevated (e.g., 10 – 30 ug/L) at the surface, averaging 10.3 ug/L and reaching a maximum of 44.0 ug/L on September 20th. Chlorophyll averaged 6.4 ug/L and 4.2 ug/L at the mid and bottom depths, respectively.
