Historical News
Week of April 9 - 15, 2023
Water Column Clarity
Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on April 13. No precipitation was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 3.0 meters, compared to 2.1 meters on the previous survey (April 5). The lowest clarity this week (2.0 meters) was measured at Phillipsdale Landing while the greatest clarity (3.3 meters) was measured at Pomham Rocks and Point St. Bridge. There was no clear north-to-south gradient in water clarity among the sites this week.
Week of November 13 - 19, 2022
Nutrients Sampling
Nutrient samples were collected from seven local river stations on November 16th and eight bay stations on November 17th. The weather leading up to the sampling day was rainy, with 1.03 inches total precipitation recorded at T.F. Green from the 11th through 15th. On the 16th, nearly another inch was recorded during the morning of sampling; the 17th was dry.
Among the river stations sampled, the highest total nitrogen (TN) and dissolved inorganic nitrogen (DIN) concentrations were observed at Ten Mile River @ Roger Williams Ave. (TN = 1,520 ppb, DIN = 1,267 ppb; average of duplicates); the highest total dissolved nitrogen (TDN) was observed at Ten Mile River @ Roger Williams Ave. and Pawtuxet River @ Broad St. (TDN = 1,610 ppb at both locations). The lowest TN, TDN, and DIN were observed at Moshassuck River @ Higginson Ave. (TN = 441 ppb, TDN = 448 ppb, DIN = 213 ppb).
Among the bay stations sampled, the highest surface nitrogen concentrations were observed at Pawtuxet Cove (TN = 1,390 ppb, TDN = 1,270 ppb, DIN = 1,069 ppb). The lowest surface TN concentration was observed at Conimicut Point (TN = 483 ppb); the lowest surface TDN and DIN concentrations were observed at Bullock Reach Buoy (TDN = 377 ppb, DIN = 231 ppb). Chlorophyll a concentrations at the surface bay stations were relatively low, averaging 1.04 μg/L across all sites with a maximum of 2.08 μg/L at Phillipsdale Landing.
Data from additional sampling dates (typically every two weeks) are pending analysis and writeup.
Week of October 30 – November 5, 2022
Nutrients Sampling
Nutrient samples were collected from seven bay stations and thirteen local river stations on November 2nd. All of the bay stations were sampled at the surface and bottom. In the five days prior to sampling, 0.05 inches of rainfall were recorded at T.F. Green.
Among the river stations sampled, the highest total nitrogen (TN) and dissolved inorganic nitrogen (DIN) concentrations were observed at Pawtuxet River @ Broad St. (TN = 1,580 ppb, DIN = 1,550 ppb). The highest total dissolved nitrogen (TDN) was observed at Ten Mile River @ Central Ave. (TDN = 1,830 ppb). The lowest TN was observed at Moshassuck River @ Higginson Ave. (TN = 487 ppb; average of duplicates). The lowest TDN was measured in one of the duplicate samples from this same site (518 ppb), while the other duplicate was slightly higher at 579 ppb. TDN was similarly low at Blackstone River @ Stateline (563 ppb). The lowest DIN was observed at Coles River @ Milford Rd. at 87.6 ppb.
Among the bay stations sampled, the highest surface nitrogen concentrations were observed at Pawtuxet Cove (TN = 1,560 ppb, TDN = 1,410 ppb, DIN = 1,260 ppb; average of duplicates). The lowest surface nitrogen concentrations were observed at Conimicut Point (TN = 380 ppb, TDN = 448 ppb, DIN = 288 ppb). Chlorophyll a concentrations at the surface bay stations were relatively low, averaging 2.23 μg/L across all sites with a maximum of 4.92 μg/L at Phillipsdale Landing.
Data from additional sampling dates (typically every two weeks) are pending analysis and writeup.
Week of February 19 - 25, 2023
Fixed Site Network
Phillipsdale Landing
Sondes were swapped for routine maintenance on the morning of February 23rd. Depth data had been lost by the sondes on February 15th but was restored with the deployment of new sondes at the swap. Data in this week’s summary should be interpreted with caution due to the lack of depth data to confirm sonde positioning for most of the week.
Weather conditions this week included light to moderate rain or snow every day, totaling 0.62 inches as recorded at TF Green. The largest rain event was on February 23rd with 0.32 inches. Blackstone River flows showed a slight increase after this rain event but remained below the 18-year median flow rates. Surface salinity this week averaged 12.6 ppt and ranged from 4.1 ppt to 22.9 ppt. At the bottom, salinity averaged 21.0 ppt and ranged from 8.7 ppt to 27.5 ppt. Temperatures at the surface averaged 5.6°C, ranging 2.9°C – 8.0°C. At the bottom, temperatures averaged 5.8°C and ranged 4.1°C – 6.7°C.
Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold of 2.9 mg/L throughout the week. Surface DO averaged 10.8 mg/L and ranged 9.2 – 12.4 mg/L. Bottom DO concentrations averaged 10.0 mg/L and ranged from 8.9 mg/L to 11.6 mg/L. Chlorophyll readings generally remained low, averaging 1.5 ug/L at the surface and 4.2 ug/L at the bottom. The maximum chlorophyll reading this week was 35.5 ug/L at the bottom on February 23rd. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.
Bullock Reach
Bullock Reach sondes will be deployed later this spring for the 2023 monitoring season.
Week of February 12 - 18, 2023
Fixed Site Network
Phillipsdale Landing
The surface sonde deployed on February 7th failed to log data internally, and so there is a data gap until DCP communications were restored this week on February 15th. Unfortunately, restoration of this connection resulted in lost depth data for both sondes through the end of the deployment on February 23rd. Data in this week’s summary should be interpreted with caution due to the gap in surface data and lack of depth data to confirm sonde positioning at both depths.
Weather conditions this week were mostly dry, with just 0.25 inches of rainfall on February 17th and trace rainfall on the 13th and 16th. Blackstone River flows continued to decline all week and fell below the 18-year median flow rates for this time of year. Surface salinity from the latter half of the week averaged 7.4 ppt and ranged from 2.0 ppt to 20.3 ppt. At the bottom, salinity averaged 20.6 ppt and ranged from 5.2 ppt to 29.8 ppt. Temperatures at the surface (latter half of the week) averaged 6.4°C, ranging 4.4°C – 8.1°C. At the bottom, temperatures averaged 5.4°C and ranged 4.6°C – 7.0°C.
Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold of 2.9 mg/L throughout the week. Surface DO (latter half of the week) averaged 11.3 mg/L and ranged 10.1 – 12.4 mg/L. Bottom DO concentrations averaged 9.9 mg/L and ranged from 8.8 mg/L to 12.3 mg/L. Chlorophyll readings generally remained low, averaging 0.8 ug/L at the surface (latter half of the week) and 2.9 ug/L at the bottom. Maximum chlorophyll at the surface reached just 6.8 ug/L in the data available this week. At the bottom, chlorophyll hit an isolated maximum of 25.1 ug/L on February 17th, though this does not appear to be related to phytoplankton activity as there were no concurrent changes to pH or DO. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.
Bullock Reach
Bullock Reach sondes will be deployed later this spring for the 2023 monitoring season.
