Historical News
Week of August 9 - 15, 2020
Nutrients Sampling
Nutrient samples were collected at eight Bay stations, surface and bottom, on August 13, 2020. Weather leading up the sample day was dry, with just 0.01 inches recorded the day prior; the most recent rainfall before that was 0.19 inches on August 4th. The highest surface total nitrogen (TN) concentration was observed in the sample from Edgewood Yacht Club, at 6,820 ppb; total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) were lower, 592 ppb and 20.5 ppb, respectively. This station also had elevated total suspended solids (93.47 ppm) and chlorophyll (423 ug/L); all of this points to substantial phytoplankton activity. Dissolved nitrogen (i.e., TDN and DIN) was highest at Pawtuxet Cove, at 829 ppb 470 ppb, respectively. The lowest TN and TDN occurred at the Bullock Reach Buoy site, which had reported values of 846 ppb and 283 ppb, respectively. DIN concentrations were lowest (13 ppb) at Pomham Rocks and Phillipsdale Landing. While the highest chlorophyll concentrations were observed at Edgewood Yacht Club, additional sites (Conimicut Point, Pomham Rocks, Phillipsdale Landing, Edgewood Shoal) exhibited elevated chlorophyll (e.g., >50 ug/L), indicative of phytoplankton bloom activity. A known Cochlodinium bloom (“rust tide”) was occurring throughout Narragansett Bay at this time.
Results from sampling on August 26, September 10, and September 23 are pending analysis.
Week of November 1 – November 7, 2020
Surface Mapping
Data were collected on November 4, 2020 while the R/V Monitor was underway collecting nutrient samples and performing vertical profiles in the Providence River estuary. The chlorophyll concentrations were good in the areas surveyed. From north to south, average chlorophyll concentrations were as follows: Upper Providence River (1.52 µg/L), Edgewood Shoals area (2.49 µg/L), Pawtuxet River area (2.47 µg/L), and Lower Providence River area (1.81 µg/L). Overall, chlorophyll ranged between non-detectable and 4.50 µg/L with an overall average of 1.98 µg/L. The chlorophyll data from this date are presented in the map below:
Week of October 25 - 31, 2020
Fixed Site Network
Phillipsdale Landing
Phillipsdale Landing sondes were changed out for routine maintenance during the morning of October 27. Water quality at this site was good this week. Precipitation totaled 1.81 inches at TF Green, with most falling on October 29 (1.33 in). The following day saw cold temperatures and the first snowfall of the season. Blackstone River flows increased in response to the precipitation, though discharges remain relatively low compared to the long-term median. This week, salinity at the surface averaged 17.9 ppt and ranged from 8.0 ppt to 25.0 ppt. Bottom salinity averaged 26.7 ppt and ranged from 16.1 ppt to 30.1 ppt. Surface and bottom water temperatures continued to cool, averaging 14.4°C and 15.9°C, respectively. Surface temperatures ranged from 9.0°C to 16.5°C, while bottom temperatures ranged from 12.5°C to 17.4°C.
Dissolved oxygen (DO) remained above the hypoxia threshold (2.9 mg/L) in surface and bottom waters this week. Surface DO averaged 7.3 mg/L, with a minimum of 4.7 mg/L, and bottom DO averaged 5.2 mg/L, with a minimum of 4.0 mg/L. Chlorophyll concentrations were low, averaging 7.3 ug/L at the surface and 4.4 ug/L at the bottom. Maximum surface chlorophyll concentrations reached 32.5 ug/L, measured on October 28. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and dissolved oxygen at this location.
Bullock Reach
Water quality was good this week at Bullock Reach. Surface salinity averaged 28.2 ppt and ranged from 26.8 ppt to 30.0 ppt. Salinity at the mid depth averaged 29.8 ppt and ranged from 27.5 ppt to 31.6 ppt, while bottom waters averaged 32.4 ppt and ranged from 29.6 ppt to 33.1 ppt. Temperatures averaged 14.9°C, 15.3°C, and 16.1°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 10.0°C to 16.9°C, mid temperatures ranged from 12.8°C to 16.9°C, and bottom temperatures ranged from 14.3°C to 16.9°C.
Dissolved oxygen (DO) concentrations remained above the hypoxia threshold (2.9 mg/L) throughout the water column. Surface DO averaged 7.3 mg/L, while mid DO averaged 7.0 mg/L. Bottom DO averaged 6.4 mg/L, with a minimum of 5.4 mg/L. Chlorophyll concentrations were low, averaging 3.2 ug/L at the surface, 3.8 ug/L in mid-depth waters, and 2.7 ug/L in bottom waters. The maximum water column chlorophyll concentration was 21.2 ug/L, measured in mid-depth waters on October 25.
Week of October 18 - 24, 2020
Fixed Site Network
Phillipsdale Landing
Water quality was good this week at Phillipsdale Landing. The weather was generally dry, with just 0.26 inches of rainfall recorded at TF Green, all on October 20. Blackstone River flows declined over the course of the week. Salinity at the surface averaged 16.9 ppt and ranged from 6.8 ppt to 24.1 ppt. Bottom salinity averaged 23.9 ppt and ranged from 15.9 ppt to 27.8 ppt. Surface and bottom water temperatures continued to cool this week, averaging 16.6°C and 16.8°C, respectively. Surface temperatures ranged from 12.9°C to 18.3°C, while bottom temperatures ranged from 15.7°C to 17.7°C.
Dissolved oxygen (DO) remained above the hypoxia threshold (2.9 mg/L) in surface and bottom waters this week. Surface DO averaged 7.3 mg/L, with a minimum of 5.3 mg/L, and bottom DO averaged 5.8 mg/L, with a minimum of 4.4 mg/L. Chlorophyll concentrations were low, averaging 9.4 ug/L at the surface and 10.1 ug/L at the bottom. Maximum surface chlorophyll concentrations reached 41.2 ug/L, measured on October 24. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and dissolved oxygen at this location.
Bullock Reach
Bullock Reach sondes were changed out for routine maintenance during the morning of October 20. Water quality was good this week at Bullock Reach. Surface salinity averaged 26.8 ppt and ranged from 24.6 ppt to 29.2 ppt. Salinity at the mid depth averaged 29.4 ppt and ranged from 27.0 ppt to 31.0 ppt, while bottom waters averaged 31.4 ppt and ranged from 29.0 ppt to 32.7 ppt. Temperatures averaged 16.8°C, 16.4°C, and 16.5°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 14.8°C to 18.9°C, mid temperatures ranged from 15.6°C to 17.4°C, and bottom temperatures ranged from 16.1°C to 16.8°C.
Dissolved oxygen (DO) concentrations remained above the hypoxia threshold (2.9 mg/L) throughout the water column. Surface DO averaged 7.8 mg/L, while mid DO averaged 7.1 mg/L. Bottom DO averaged 6.6 mg/L, with a minimum of 5.4 mg/L. Chlorophyll concentrations were low, averaging 5.1 ug/L at the surface, 3.6 ug/L in mid-depth waters, and 2.9 ug/L in bottom waters. The maximum water column chlorophyll concentration was 19.1 ug/L, measured in mid-depth waters on October 24.
Week of October 11 - 17, 2020
Fixed Site Network
Phillipsdale Landing
Phillipsdale Landing sondes were changed out for routine maintenance during the morning of October 14. Water quality was good this week at Phillipsdale Landing. The weather was rainy, with a total of 3.08 inches recorded at TF Green over the course of the week. The majority of the rainfall occurred in two storms, the first on October 13 (1.11 in.) and the second on October 17 (1.23 in.). Blackstone River flows increased markedly, and salinity declined following these rain events. Salinity at the surface averaged 20.6 ppt and ranged from 8.6 ppt to 27.0 ppt. Bottom salinity averaged 25.8 ppt and ranged from 13.8 ppt to 29.4 ppt. Surface and bottom water temperatures continued to cool this week, averaging 17.2°C and 17.7°C, respectively. Surface temperatures ranged from 13.8°C to 18.6°C, while bottom temperatures ranged from 16.4°C to 18.7°C.
Dissolved oxygen (DO) remained above the hypoxia threshold (2.9 mg/L) in surface and bottom waters this week. Surface DO averaged 8.4 mg/L, with a minimum of 5.7 mg/L, and bottom DO averaged 6.4 mg/L, with a minimum of 4.9 mg/L. Chlorophyll concentrations decreased toward the end of the week, averaging 37.1 ug/L at the surface and 23.0 ug/L at the bottom. Maximum surface chlorophyll concentrations were around 88 ug/L, measured on October 11 and 12. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and dissolved oxygen at this location.
Bullock Reach
Water quality was good this week at Bullock Reach. Surface salinity averaged 28.7 ppt and ranged from 26.6 ppt to 30.2 ppt. Salinity at the mid depth averaged 29.7 ppt and ranged from 27.6 ppt to 30.9 ppt, while bottom waters averaged 30.8 ppt and ranged from 28.5 ppt to 31.7 ppt. Temperatures averaged 17.1°C at all three depths. Surface temperatures ranged from 15.3°C to 18.0°C, mid temperatures ranged from 16.3°C to 17.9°C, and bottom temperatures ranged from 16.5°C to 17.8°C.
Dissolved oxygen (DO) concentrations remained above the hypoxia threshold (2.9 mg/L) throughout the water column. Surface DO averaged 7.5 mg/L, while mid DO averaged 7.3 mg/L. Bottom DO averaged 7.0 mg/L, with a minimum of 6.3 mg/L. Chlorophyll concentrations were low, averaging 5.4 ug/L at the surface, 3.3 ug/L in mid-depth waters, and 3.9 ug/L in bottom waters. The maximum water column chlorophyll concentration was 16.4 ug/L, measured in surface waters on October 11.
