April 22 – 28, 2024

​Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was good this week. Weather conditions were dry, with only 0.05 inches on April 30th, recorded at T.F. Green. The Blackstone River flow declined this week, remaining below the 19-year daily median for the majority of the week. Surface salinity averaged 4.1 ppt and ranged from 1.2 ppt to 9.1 ppt. At the bottom, salinity averaged 13.5 ppt and ranged from 2.3 ppt to 27.1 ppt. Temperatures remained stabilized this week, averaging 12.7°C at the surface and ranging 10.0°C – 14.5°C. At the bottom, temperatures averaged 11.3°C and ranged 8.0°C – 14.4°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO average 10.5 mg/L and ranged from 9.5 mg/L to 11.7 mg/L.. Bottom DO concentrations averaged 9.3 mg/L and ranged from 8.1 mg/L to 11.3 mg/L. Chlorophyll readings remained comparable from last week, averaging 2.6 ug/L at the surface and 2.9 ug/L at the bottom. Maximum chlorophyll at the surface reached 14.3 ug/L on the afternoon of April 24th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. Also, please note that isolated portions of suspect chlorophyll data from April 28th were excluded from the summary.

Bullock Reach 

The Bullock Reach Buoy remains out of the water for the winter.  EM will coordinate with RIDEM to redeploy the buoy in late spring.

Week of April 15 – 21, 2024

​Phillipsdale Landing

Sondes were swap this week on the morning of April 16th. Overall, water quality at Phillipsdale Landing was good this week. Weather conditions were mostly dry, with only 0.4 inches of precipitation recorded at T.F. Green. The Blackstone River flow declined this week, remaining above the 19-year daily median for the week. Salinity at the surface averaged 1.8 ppt and ranged from 0.4 ppt to 4.4 ppt. At the bottom, salinity averaged 9.2 ppt and ranged from 0.4 ppt to 26.3 ppt. Temperatures continued to increase this week, averaging 12.9°C at the surface and 11.6 °C at the bottom. Surface temperatures ranged from 10.7°C to 15.5°C, while bottom temperatures ranged from 8.1°C to 15.3°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO remained similar to the previous week, averaging 10.5 mg/L and ranging 9.7-11.8 mg/L. Bottom water DO concentration averaged 9.7 mg/L and ranged from 7.7 mg/L to 11.6 mg/L. Chlorophyll concentrations remained low,  averaging 2.7 ug/L at the surface and 2.6 ug/L at the bottom. Maximum surface chlorophyll readings reached 11.9 ug/L, recorded in the morning of April 20th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. Also, please note that isolated portion of suspect chlorophyll data from April 15th was excluded from the summary.

Bullock Reach 

The Bullock Reach Buoy remains out of the water for the winter.  EM will coordinate with RIDEM to redeploy the buoy in late spring.

Week of April 8 – 14, 2024

​Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was good this week. Weather conditions included sporadic rain events, with 1.0 inches of precipitation recorded at T.F. Green. The Blackstone River flow increased during the 12th and 13th and remained above the 19-year daily median for the week. Surface salinity this week averaged 2.4 ppt and ranged from 0.2 ppt to 7.5 ppt. At the bottom, salinity averaged 8.6 ppt and ranged from 0.2 ppt to 26.4 ppt. Temperatures increased this week, averaging 10.5°C at the surface and 9.8°C bottom. Surface temperatures ranged from 6.5°C to 12.3°C, while bottom temperatures ranged from 5.9°C to 12.5°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 11.5 mg/L and ranged 10.0 – 12.7 mg/L. Bottom DO concentrations averaged 11.0 mg/L and ranged from 9.1 mg/L to 12.6 mg/L. Chlorophyll concentrations remained low, averaging 2.3 ug/L at the surface and 4.2 ug/L at the bottom. Maximum chlorophyll at the surface reached 15.1 ug/L on the morning of April 12th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. Also, please note that isolated portions of suspect chlorophyll data from April 8th to the 11th were excluded from the summary.

Bullock Reach 

The Bullock Reach Buoy remains out of the water for the winter.  EM will coordinate with RIDEM to redeploy the buoy in late spring.

Week of April 1 – 7, 2024

​Phillipsdale Landing

The Phillipsdale Landing sondes have been deployed for the season since April 2nd, 2024. Overall, water quality at Phillipsdale Landing was good this week. Weather conditions were wet this week, with a total of 2.22 inches recorded at T.F. Green, and the majority of rainfall occurring between the 2nd and 4th.  The Blackstone River flow increased during the 4th and remained above the 19-year daily median for the week. Salinity at the surface averaged 1.8 ppt and ranged from 0.2 ppt to 5.7 ppt. At the bottom, salinity averaged 9.2 ppt and ranged from 0.2 ppt to 27.6 ppt. Temperatures this week averaged 7.4°C at the surface and 6.7°C at the bottom. Surface temperatures ranged from 5.8°C to 9.9°C, while bottom temperatures ranged from 5.6°C to 8.9°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO averaged 12.2 mg/L and ranged from 11.0-13.5 mg/L. Bottom water DO concentration averaged 11.6 mg/L and ranged from 9.2 mg/L to 13.6 mg/L. Chlorophyll remained low, averaging 1.6 ug/L at the surface and 3.1 ug/L at the bottom. Maximum surface chlorophyll readings reached 4.3 ug/L, recorded on the morning of April 4th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. Also, please note that an early portion of the bottom data is not included in the summary above due to bottom deployment getting into position.

Bullock Reach

The Bullock Reach Buoy remains out of the water for the winter.  EM will coordinate with RIDEM to redeploy the buoy in late spring.

​

April 24, 2024

On April 24th, twenty stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers; five of these stations were also sampled for enterococci bacteria. In the five days prior to sampling, precipitation totaled 0.28 inches as recorded at TF Green. Overall, bacteria counts were lower in both the Seekonk and Providence Rivers this week than during the previous sampling event on March 27th, likely because of the drier weather leading up to sampling. 

Fecal coliform counts were higher in the Seekonk River sites than in the Providence River sites (geometric means of 59 MPN/100 mL and 7 MPN/100 mL, respectively). The maximum count (430 MPN/100 mL) was measured at Point St Bridge. 

Enterococci results had an overall geometric mean of 14 MPN/100 mL. Enterococci counts ranged from <10 MPN/100 mL at South FP East, Gaspee Point, and Conimicut Point to 41 MPN/100 mL at Phillipsdale Landing.

The next scheduled sampling date is May 8.

The table below lists the Rhode Island bacteria standards for primary contact and shellfishing established by the Rhode Island Department of Environmental Management (RIDEM). RIDEM defines primary contact as any recreational activities in which there is prolonged and intimate contact with water, involving considerable risk of ingesting water (e.g., swimming, diving, water skiing and surfing). Please note that the RIDEM bacteria standards are provided here for informational purposes only and are not intended to indicate official state compliance with primary contact or shellfishing standards.

Summary of Rhode Island Bacteria Standards for Saltwater Primary Contact and Shellfishing

 ​​Fec​al Coli​fo​rmEnterococci
Primary Con​​​t​a​c​t1​​​​​Geom​e​tric ​m​e​a​n​ ≤50 MPN/1​​00​ mL
<10% ​o​f​​ samples >400 MPN/100 ​mL		Geom​etric mean ≤35 colo​nies​/100 mL​
All sa​mples ≤104 colonies/100 ​​mL2
ShellfishingGeometric mean ≤14 MPN/100​ mL
<10% of samples >49 MPN/100 mL3​		NO ENTEROCOCCI CR​ITERIA

1Fecal coliform primary contact criteria app​lied only when adequate enterococci data are not available; 2Single sample maximum criterion for determining beach swimming advisories at designated beaches as evaluated by the Rhode Island Department of Health; 3For a three-tube decimal dilution

Table adapted from Rhode Island Water Quality Regulations (250-RICR-150-05-1)​; see regulations for complete details.​​​​​​​​​​

April 16-17, 2024

​Nutrient samples were collected from seven river stations on April 17th and eight bay stations on April 16th. In the five days prior to sampling, there were 1.04 inches of precipitation recorded at T.F. Green. 

Among the river stations sampled, the highest total nitrogen (TN), and dissolved inorganic nitrogen (DIN) concentrations were observed at Blackstone River @ Slater Mill (TN = 751 ppb, DIN = 571 ppb).  The highest total dissolved nitrogen (TDN) was observed at Blackstone River @ Bikepath Bridge (TDN = 787 ppb). The lowest TN, TDN, and DIN were observed at Moshassuck River @ Higginson Ave. (TN = 483.5 ppb, TDN = 489 ppb, DIN = 291 ppb, all averaged with duplicates).

Among the bay stations sampled, the highest surface TN, TDN, and DIN were observed at Phillipsdale Landing Surface (TN = 844 ppb, TDN = 678, and DIN = 545 ppb).  The lowest surface TN were at Pawtuxet Cove (TN = 633 ppb). The lowest surface TDN were observed at Bullock Reach Buoy (TDN = 402 ppb, average of duplicates). The lowest surface DIN were observed at Conimicut Point Surface (DIN = 301 ppb). Chlorophyll a concentrations at the surface bay stations averaged 2.39 μg/L overall with a maximum of 3.35 μg/L at the Conimicut Point.

The next scheduled sampling date is May 1, 2024.

April 3, 2024

Nutrient samples were collected from thirteen river stations on April 3rd. In the five days prior to sampling, there were 1.44 inches of precipitation 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 were observed at Ten Mile River @ Central Ave. (TN = 1,120 ppb, TDN = 1,150 ppb, DIN = 866 ppb). The lowest TN, TDN, and DIN were observed at Coles River @ Milford Road (TN = 531 ppb, TDN = 494 ppb, DIN = 130 ppb).

The next scheduled sampling date is April 17, 2024.

March 20, 2024

​Nutrient samples were collected from seven river stations and eight bay stations on March 20th. All bay stations were sampled at the surface and bottom. In the five days prior to sampling, there were 0.2 inches of precipitation recorded at T.F. Green. 

Among the river stations sampled, the highest total nitrogen (TN) and total dissolved nitrogen (TDN) were observed at Blackstone River @ Bikepath Bridge (TN=906 ppb, TDN = 928 ppb), while the highest dissolved inorganic nitrogen (DIN) was at the Blackstone River @ Slater Mill (DIN=735 ppb). The lowest TN, TDN, and DIN were observed at Moshassuck River @ Higginson Ave (TN=559.5 ppb, TDN=567.5 ppb, DIN=401 ppb, all averaged with duplicates).

Among the bay stations sampled, the highest surface TN, TDN, and DIN were observed at Phillipsdale Landing (TN = 1,080 ppb, TDN = 961 ppb, DIN = 765 ppb). The lowest surface TN, TDN, and DIN were observed at the Bullock Reach Buoy (TN = 460 ppb, TDN = 177 ppb, DIN = 73 ppb). Chlorophyll a concentrations at the surface bay stations averaged 6.22 μg/L overall with a maximum of 15.01 μg/L at the Bullock Reach Buoy.

The next scheduled sampling date is April 3, 2024.

April 16, 2024

​Phytoplankton samples were collected on April 16, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. It was a sunny and calm day on Narragansett Bay. Some lions mane jellyfish were detected. The qualitative tow net sample had a fast filtration time, and the filtrate was a clear yellow-brown color. 

The analysis of the quantitative whole water sample revealed a total of 1,038,000 cells per Liter. The micro flagellates were found at 32,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 529,000 cells/L. Other representative genera include Leptocylindrus spp. and Chaetoceros spp. Actinoptychus spp. is a type of photosynthetic phytoplankton belonging to the centric diatom group. It is found in Narragansett Bay and widely distributed in spring and fall. It is identified by six radial sectors. The raised sectors can appear to look like a hazard sign, as seen in this 200x phase-contrast image.​

March 17-23, 2024

​Phytoplankton samples were collected on March 20, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. It was partly sunny, breeze and brisk on Narragansett Bay. The qualitative tow net sample had a long filtration time, and the filtrate was a dark brown color. Some sediment and jellyfish were found in the sample. 

The analysis of the quantitative whole water sample revealed a total of 3,536,000 cells per Liter. The micro flagellates were found at 20,000 cells/L. The most predominant phytoplankton genus was Thalassiosira spp. at 1,888,000 cells/L. Other representative genera include Skeletonema spp. and Leptocylindrus spp.​ Thalassiosira spp. (today’s featured micrograph, 200x phase contrast) is a type of ​​phytoplankton belonging to the centric diatom group. This photosynthetic species grows primarily in marine waters. Some species within the genus are found in estuaries and aquatic systems that have been impacted by human activities. They can be identified by their coin-like shape.

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