Nicole Skyleson – Page 5

September 23 – 29, 2024

Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was good to fair this week. Weather conditions included a rain event, with 1.06 inches of precipitation recorded at T.F. Green. The Blackstone River flow fluctuated through the week in response to rain, though it remained below the 20-year daily median through the week. Surface salinity averaged 23.7 ppt and ranged from 16.3 ppt to 27.8 ppt. At the bottom, salinity averaged 27.6 ppt and ranged from 24.6 ppt to 29.7 ppt. Temperatures continued to decline this week, averaging 19.4°C at the surface and ranging 17.9°C – 21.0°C. At the bottom, temperatures averaged 19.5°C and ranged 18.9°C – 20.2°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) at the surface throughout the week, while DO at the bottom waters dropped below the hypoxic threshold throughout the week. Surface DO averaged 6.16 mg/L and ranged from 3.77 mg/L to 8.88 mg/L. Bottom DO concentrations averaged 4.3 mg/L and ranged from 2.2 mg/L to 5.7 mg/L. The longest period of hypoxic conditions (1 hour) occurred at the bottom depth on the afternoon of September 26^th. During this period, bottom DO averaged around 2.51 mg/L. Chlorophyll readings decreased from last week, averaging 15.1 µg/L at the surface and 6.0 µg/L at the bottom. Maximum chlorophyll at the surface reached 59.98 µg/L on the afternoon of September 29^th. 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 this week on the morning of September 24^th. Overall, the water quality was good at Bullock Reach this week. Salinity averaged 28.8 ppt, 30.2 ppt, and 31.8 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 26.5 – 30.1 ppt, mid salinity ranged 28.7 – 31.4 ppt, and bottom salinity ranged 29.8 – 32.3 ppt. Surface temperature averaged 19.1°C and ranged from 18.1°C to 20.8°C. Mid temperatures averaged 19.0°C and ranged from 18.5°C to 20.2°C. Bottom temperatures averaged 18.8°C and ranged from 18.7°C to 19.2°C.

DO at Bullock Reach remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 7.2 mg/L and ranged 6.2 – 8.7 mg/L. In the mid waters, DO averaged 6.6 mg/L and ranged 5.7 – 7.7 mg/L. At the bottom, DO averaged 6.1 mg/L and ranged 5.4 – 6.9 mg/L. Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the week. Readings averaged 9.2 µg/L at the surface, 7.5 µg/L at mid-depth, and 2.6 µg/L at the bottom. The maximum surface chlorophyll was 21.2 µg/L on the evening of September 25^th.

May 28, 2025

Nutrient samples were collected from fourteen river stations and eight bay stations on May 28^th. All bay stations were sampled at the surface and one station (Edgewood Shoal) was sampled at the bottom. In the five days prior to sampling, 0.06 inches of precipitation 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) were observed Ten Mile River @ Central Ave. (TN = 1,050 ppb, TDN = 1,100 ppb, DIN = 757). The lowest TN, and TDN were observed at Moshassuck River @ Higginson Ave. (TN = 458 ppb, TDN = 552 ppb). The lowest DIN was observed at Coles River @ Milford Rd. (DIN = 116 ppb).

Among the bay stations sampled, the highest surface total nitrogen (TN) was observed at Phillipsdale Landing (TN = 870 ppb). The highest total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed at Pawtuxet Cove (TDN = 771 ppb, DIN = 568 ppb). The lowest surface TN was observed at the Bullock Reach Buoy (TN = 584). The lowest surface TDN and DIN concentrations were observed at Conimicut Point (TDN = 214 ppb, DIN = 72 ppb).

The next scheduled sampling date is June 11, 2025.

May 14, 2025

Nutrient samples were collected from seven river stations and seven bay stations on May 14^th. All bay stations were sampled at the surface and the bottom. In the five days prior to sampling, 0.29 inches of precipitation were recorded at T.F. Green.

Among the river stations sampled, the highest total nitrogen (TN) was observed at Blackstone River @ Bikepath Bridge. (TN = 823 ppb). The highest total dissolved nitrogen (TDN) was observed at Blackstone River @ Slater Mill (TDN = 993 ppb). The highest dissolved inorganic nitrogen was observed at Pawtuxet River @ Broad St. (DIN = 520 ppb). The lowest TN, and DIN were observed at the Moshassuck River @ Footbridge at Mill St. (TN = 636 ppb, DIN = 683 ppb). The lowest TDN was observed at Blackstone River @ Stateline (TDN 428 ppb).

Among the bay stations sampled, the highest surface total nitrogen (TN) was observed at India Point Park (TN = 857 ppb). The highest total dissolved nitrogen (TDN) was observed at Phillipsdale Landing (TDN = 736 ppb). The highest dissolved inorganic nitrogen (DIN) was observed at Pawtuxet Cove (DIN = 453 ppb). The lowest surface TN, TDN and DIN concentrations were observed at Conimicut Point (TN = 645 ppb, TDN = 359 ppb, DIN = 183 ppb).

The next scheduled sampling date is May 28, 2025.

April 30, 2025

Nutrient samples were collected from seven river stations April 30^th. In the five days prior to sampling, 0.76 inches of precipitation were recorded at T.F. Green.

The highest total nitrogen (TN), total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) concentrations were observed at Pawtuxet River @ Broad St. (TN = 1,120 ppb, TDN = 1,100 ppb, DIN = 875 ppb). The lowest TN, TDN and DIN concentrations were observed at Moshassuck River @ Footbridge at Mill St. (TN =670 ppb, TDN = 722 ppb, DIN = 427 ppb).

The next scheduled sampling date is May 14, 2025.

April 16-17, 2025

Nutrient samples were collected from seven river stations on April 16^th and seven bay stations 17^th. All bay stations were sampled at the surface and bottom except for one station (India Point Park) which was only sampled at the surface. In the five days prior to sampling, 0.80 inches of precipitation were recorded at T.F. Green. Due to a laboratory issue, some ammonia and dissolved inorganic nitrogen (DIN) results for the bay and river samples are not available. The DIN for both the bay and river stations will be based on the results available.

Among the river stations sampled, the highest total nitrogen (TN) was observed at Blackstone River @ Slater Mill (TN = 953 ppb). The highest total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) was observed at Pawtuxet River @ Broad St. (TDN = 930 ppb, DIN = 673 ppb). The lowest TN and TDN were observed at Moshassuck River @ Footbridge at Mill St. (TN = 569 ppb, TDN = 517 ppb). The lowest DIN was observed at Blackstone River @ Bikepath Bridge. (DIN = 614 ppb).

Among the bay stations sampled, the highest surface total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed at Phillipsdale Landing (TN = 1,250 ppb, TDN = 975 ppb, DIN = 801 ppb). The lowest surface TN and DIN concentrations were observed at Conimicut Point (TN = 504 ppb, DIN = 79 ppb). The lowest surface TDN was observed at the Bullock Reach Buoy (TDN = 178 ppb).

The next scheduled sampling date is April 30, 2025.

April 2, 2025

Nutrient samples were collected from twelve river stations on April 2^nd. In the five days prior to sampling, 0.25 inches of precipitation were recorded at T.F. Green.

The highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed at Ten Mile River @ Central Ave. (TN = 2,040 ppb, TDN = 2,020 ppb, DIN = 1,731). The lowest TN, and TDN concentrations were observed at Moshassuck River @ Footbridge at Mill St. (TN = 546 ppb, TDN = 543 ppb). The lowest DIN concentration was observed at Coles River @ Milford Rd. (DIN = 160 ppb).

The next scheduled sampling date is April 16, 2025.

March 19, 2025

Nutrient samples were collected from seven river stations and eight bay stations on March 19^th. All bay stations were sampled at the surface and the bottom. In the five days prior to sampling, 2.21 inches of precipitation 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) were observed at Blackstone River @ Slater Mill (TN = 1,220 ppb, TDN = 1,160, DIN = 810). The lowest TN, and TDN concentrations were observed on the Woonasquatucket River @ Manton Ave. Bridge (TN = 624 ppb, TDN = 617 ppb). The lowest DIN was observed at Moshassuck River @ Footbridge at Mill St. (DIN = 407 ppb).

Among the bay stations sampled, the highest surface total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed at Phillipsdale Landing (TN = 1,450 ppb, TDN = 1,290 ppb, DIN = 889 ppb). The lowest surface TN was observed at Pomham Rocks (TN = 766 ppb). The lowest surface TDN and DIN concentrations were observed at Conimicut Point Surface (TDN = 475 ppb, DIN = 223 ppb).

The next scheduled sampling date is April 2, 2025.

March 5, 2025

Nutrient samples were collected from six river stations on March 5^th. In the five days prior to sampling, there was no precipitation recorded at T.F. Green.

The highest total nitrogen (TN), total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) concentrations were observed at Pawtuxet River @ Broad St. (TN = 1,590 ppb, TDN = 1,770 ppb, DIN = 1,533 ppb). The lowest TN, TDN, and DIN concentrations were observed on the Moshassuck River @ Footbridge at Mill St. (TN =558 ppb, TDN = 592 ppb, DIN = 441 ppb).

The next scheduled sampling date is March 19, 2025.

June 25, 2025

Surface chlorophyll data were collected on June 25, 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 the Seekonk River, and as good in all other areas. The average chlorophyll concentrations were categorized as good in all areas surveyed. Overall, chlorophyll ranged from 0.39 µg/L to 17.96 µg/L with an average of 2.01 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

June 11, 2025

Surface chlorophyll data were collected on June 11, 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 Pawtuxet River, and as fair in all other areas. Overall, chlorophyll ranged from 2.85 µg/L to 28.47 µg/L with an average of 19.66 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.