Historical News

Week of September 5 - 11, 2021

Fixed Site Network

Phillipsdale Landing

Water quality at Phillipsdale Landing was fair-to-poor this week. Blackstone River flows remained elevated above historical mean flows, though generally declined over the course of the week. Rainfall was light to moderate, just 0.2 inches on September 6th and 0.5 inches on September 9th as measured at TF Green. Salinity at the surface averaged 3.4 ppt and ranged 0.5-8.1 ppt. Bottom salinity averaged 13.6 ppt and ranged 1.3-29.4 ppt. Water temperatures cooled slightly compared to the previous week, averaging 21.2°C on the surface and 21.3°C on the bottom. Temperatures ranged from 19.3°C to 22.7°C at the surface and from 19.6°C to 22.5°C at the bottom.

Surface dissolved oxygen (DO) averaged 7.7 mg/L, with a minimum of 6.3 mg/L. Bottom DO continued to dip below the hypoxia threshold (2.9 mg/L) during most high tide periods, generally decreasing over the course of the week. The average bottom DO was 4.9 mg/L, with a minimum of 1.7 mg/L and maximum of 8.8 mg/L. The longest duration of hypoxic conditions this week was on September 11th for approximately 7 hours around the mid-day high tide. Chlorophyll concentrations remained low, averaging 2.6 ug/L on the surface and 1.8 ug/L on the bottom, with a surface maximum of 8.2 ug/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 fair this week. Salinity at the surface averaged 21.5 ppt and ranged from 15.8 ppt to 25.2 ppt. Salinity at the mid depth averaged 26.6 ppt and ranged from 22.3 ppt to 29.9 ppt. Salinity in bottom waters averaged 29.5 ppt and ranged from 24.1 ppt to 31.7 ppt. Temperatures cooled slightly since the previous week, averaging 22.1°C, 21.9°C, and 21.3°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 20.8°C to 23.2°C, mid temperatures ranged from 21.3°C to 22.9°C, and bottom temperatures ranged from 20.7°C to 22.6°C.

DO concentrations improved this week, averaging 6.7 mg/L at the surface, 5.2 mg/L at mid-depth, and 3.7 mg/L at the bottom. Hypoxic conditions (DO ≤ 2.9 mg/L) were observed only in bottom waters and only for isolated short durations. The longest period of hypoxia this week was approximately 1 hour during the evening of September 8th. Chlorophyll concentrations averaged 13.4 ug/L at the surface and 10.5 ug/L at mid-depth. Concentrations increased in the latter half of the week, suggestive of phytoplankton bloom activity. The maximum chlorophyll value in surface waters was 64.8 ug/L, on September 11th.

Week of August 29 – September 04, 2021

Fixed Site Network

Phillipsdale Landing

Water quality at Phillipsdale Landing was fair-to-poor this week. Sondes were swapped for routine maintenance during the morning of August 31st. Rainfall this week totaled 3.95 inches at TF Green, with a majority of the rainfall (3.89 inches) occurring in the first two days of September. Impacted by the heavy rainfall at the end of the week, Blackstone River flows increased as the week progressed while remaining elevated over historical median levels. In response to the heavy rainfall, surface salinity decreased this week, averaging 3.8 ppt with a maximum value of 12.8 ppt. Bottom salinity averaged 15.4 ppt, with a maximum value of 30.1 ppt. Water temperatures averaged 22.5°C on the surface and 22.3°C on the bottom. Temperatures ranged from 19.0°C to 25.7°C at the surface and from 19.0°C to 24.8°C at the bottom.

This week, surface dissolved oxygen (DO) averaged 7.5 mg/L, with a minimum of 3.8 mg/L. Bottom DO generally increased over the course of the week, averaging 4.1 mg/L and ranging from <1.0 mg/L to 10.1 mg/L. Bottom water hypoxia (DO ≤ 2.9 mg/L) was persistent throughout the first half of the week. Chlorophyll concentrations were slightly lower than the previous week, averaging 5.2 ug/L on the surface and 3.5 ug/L on the bottom, with a surface maximum of 16.2 ug/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 fair-to-poor this week. Overall, salinity remained similar over the course of the week, averaging 22.4 ppt at the surface, 28.7 ppt at mid-depth, and 31.0 ppt in bottom waters. Lowest salinity (15.5 ppt) occurred in surface waters, while greatest salinity (32.3 ppt) occurred in bottom waters. Temperatures averaged 23.2°C, 23.0°C, and 22.2°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 20.5°C to 25.7°C, mid temperatures ranged from 21.2°C to 24.7°C, and bottom temperatures ranged from 20.5°C to 23.5°C.

This week, DO averaged 7.2 mg/L at the surface, 4.0 mg/L at mid-depth, and 3.4 mg/L at the bottom. Hypoxic conditions (DO ≤ 2.9 mg/L) were observed at the mid and bottom depths. The minimum DO value, 1.7 mg/L, occurred in bottom waters during the morning of August 31, which was during a period of prolonged hypoxia that lasted approximately 13 hours. Chlorophyll concentrations averaged 15.2 ug/L at the surface and 10.8 ug/L at mid-depth. The maximum chlorophyll value in surface waters was 35.4 ug/L.


Week of August 22 – 28, 2021

Nutrients Sampling

Nutrient samples were collected from thirteen local and border river stations and eight bay stations on August 25, 2021. Nearly 1 inch of rainfall was recorded at T.F. Green in the three days prior to sampling.

Among the river stations sampled, total nitrogen (TN) ranged from 462 ppb (average of 2 duplicates) at Moshassuck River at Higginson Ave. to 1,530 ppb at the Warren Reservoir/Kickemuit River. Concentrations of total dissolved nitrogen (TDN) were also lowest at the Moshassuck River at Higginson Ave. site (average of two duplicates = 468 ppb), while highest TDN concentration was measured at the Ten Mile River at Central Ave. site (1,260 ppb). Additionally, dissolved inorganic nitrogen (DIN) ranged from 163 ppb at the Runnins River at River Road sampling location to 901.3 ppb at the Ten Mile River at Central Ave. site.

Among the Bay stations sampled, the highest nitrogen results occurred at Pawtuxet Cove, which had TN, TDN, and DIN results of 944 ppb, 1,140 ppb, and 613.4 ppb, respectively. The lowest TN (540 ppb), TDN (662 ppb), and DIN (115.2 ppb) occurred at the Bullock Reach Buoy site (average of duplicates reported). Chlorophyll a concentration at the Bay sites decreased from the previous week, averaging 8.68 ug/L. The maximum chlorophyll result, 16.77 ug/L, occurred in one of the duplicate samples at Bullock Reach Buoy (average of duplicates = 14.38 ug/L).

Results from nutrient sampling on September 8 and September 22 are pending analysis. The next scheduled sample date is October 6.

Week of August 22 – 28, 2021

Fixed Site Network

Phillipsdale Landing
Water quality at Phillipsdale Landing was fair-to-poor this week. Conditions this week were mostly wet, with 1.78 inches of rainfall recorded at TF Green. Blackstone River flows remained elevated over historical median levels, based on heavy rainfall this week. Surface salinity averaged 5.4 ppt, with a maximum value of 13.1 ppt. Bottom salinity averaged 17.2 ppt, with a maximum value of 27.5 ppt. Water temperatures averaged 25.4°C on the surface and 24.3°C on the bottom. Temperatures ranged from 23.6°C to 29.1°C at the surface and from 23.3°C to 26.1°C at the bottom.

This week, surface dissolved oxygen (DO) averaged 6.3 mg/L, with a minimum of 3.9 mg/L. Bottom DO generally decreased over the course of the week and ranged from 1.7 mg/L to 6.8 mg/L; bottom hypoxia (DO ≤ 2.9 mg/L) was common. Chlorophyll concentrations were lower than the previous week, averaging 5.6 ug/L on the surface and 4.8 ug/L on the bottom, with a surface maximum of 17.7 ug/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 fair-to-poor this week. Sondes were changed out for routine maintenance on August 24. Salinity generally increased slightly over the course of the week, averaging 22.2 ppt at the surface, 27.3 ppt at mid-depth, and 29.9 ppt in bottom waters. Salinity ranged from 18.3 ppt to 26.1 ppt at the surface, 21.6 ppt to 29.6 ppt at the mid-depth, and 27.9 ppt to 31.2 ppt at the bottom. Surface temperature averaged 25.4°C and ranged 24.0°C – 27.8°C, mid temperatures averaged 24.3°C and ranged 23.4°C – 26.0°C, and bottom temperatures averaged 23.2°C and ranged 22.3°C – 24.2°C.

This week, DO averaged 7.5 mg/L at the surface, 4.8 mg/L at mid-depth, and 3.9 mg/L at the bottom. Hypoxic conditions (DO ≤ 2.9 mg/L) were observed at the mid and bottom depths. The minimum DO value, 2.6 mg/L, occurred in bottom waters on August 28, during a period of hypoxic conditions that lasted approximately two hours. Chlorophyll concentrations averaged 15.7 ug/L at the surface, 9.8 ug/L at mid-depth, and 1.7 ug/L at the bottom. The maximum chlorophyll value in surface waters was 119.4 ug/L.​

Week of August 8 – 14, 2021

Nutrients Sampling

Nutrient samples were collected from seven local and border river stations and seven bay stations (surface and bottom) on August 11, 2021. In the five days prior to sampling, only trace amounts of rainfall were recorded at T.F. Green.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) concentrations occurred at the Pawtuxet River at Broad St. site. At this sampling location, TN, TDN, and DIN concentrations were 1,220 ppb, 1,420 ppb, and 1,080.3 ppb, respectively. The lowest nitrogen concentrations occurred at Moshassuck River at Higginson Ave., with concentrations of 418 ppb (TN), 500 ppb (TDN), and 252.1 ppb (DIN).

Among the Bay surface station results, TN ranged from 375 ppb at Conimicut Point to 715 ppb at Phillipsdale Landing. Lowest TDN (139 ppb) occurred at Bullock Reach Buoy, while the greatest TDN value occurred at Phillipsdale Landing (706 ppb). Additionally, DIN ranged from 13.0 ppb at Edgewood Yacht Club to 431.6 ppb at Phillipsdale Landing. Chlorophyll a concentration at the Bay sites decreased since the previous sampling at the end of July, averaging 16.23 ug/L. The maximum result of 25.06 ug/L occurred at Phillipsdale Landing. 

Results from nutrient sampling on August 25 and September 8 are pending analysis. The next scheduled sample date is September 22.

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