Historical News

Week of November 17 - 23, 2019

Nutrients Sampling

Nutrient samples were collected at seven local river stations and seven bay stations (surface and bottom) on November 20, 2019. The sampling day was preceded by approximately 0.25 inches of rainfall over the two days prior.

Among the river stations sampled, highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed in the sample from the Ten Mile River at Roger Williams Avenue, at 1,680 ppb, 1,760 ppb, and 1,440.6 ppb, respectively. The lowest TN (631 ppb) and TDN (345 ppb) results were observed at the Pawtuxet River at Broad Street, though results from the Moshassuck River at Higginson Avenue were similarly low (641 ppb and 360.5 ppb, respectively, average of duplicates). DIN results were also lowest at these two sites, with 206.2 ppb at the Pawtuxet River and 162.9 ppb (average of duplicates) at the Moshassuck River.

Among the bay stations sampled, the greatest TN (1,055 ppb) and DIN (774.5 ppb) in surface waters occurred at Pawtuxet Cove (average of duplicates); the highest TDN (912 ppb) occurred at Phillipsdale Landing. The lowest surface TN (468 ppb), TDN (217 ppb), and DIN (198.8 ppb) occurred at India Point Park.

Results from sampling on December 4 and 18 are pending analysis. The next scheduled date of sampling is January 2, 2020.

Week of November 3 - 9, 2019

Nutrients Sampling

Nutrient samples were collected at fourteen local and border river stations and eight bay stations on November 6, 2019; most bay stations were sampled at the surface only, with Edgewood Shoal sampled at the surface and bottom. The sampling day was preceded by approximately half an inch of rainfall on the day before.

Among the river stations sampled, highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed in the sample from the Ten Mile River at Central Avenue site, at 1,880 ppb, 1,960 ppb, and 1,617.9 ppb, respectively. The lowest TN and TDN values occurred in the samples from the Moshassuck River at Higginson Avenue, with results of 433 ppb and 459 ppb; the lowest DIN results were from Coles River at Milford Road, at 78.6 ppb (average of duplicates).

Among the bay stations sampled, the greatest TN (1,170 ppb), TDN (1,010 ppb), and DIN (773 ppb) in surface waters occurred at Phillipsdale Landing. The lowest surface TN (605 ppb), TDN (290 ppb), and DIN (244.5 ppb) occurred at Edgewood Shoal (average of duplicates).

Results from sampling on November 20 and December 4 and 18 are pending analysis. The next scheduled date of sampling is January 2, 2020.

Week of December 15 - 21, 2019

Fixed Site Network

Phillipsdale Landing
Water quality was good this week at Phillipsdale Landing. This week was drier than last week, with 0.69 inches of precipitation recorded at TF Green Airport, however, the impact of nearly 2 inches of rainfall occurring on December 14 was evident in the early portion of the week. Surface and bottom salinity generally remained low through December 15 and 16 and began to increase through the remainder of the week. Surface salinity averaged 3 ppt, ranging from 0.2 to 8.1 ppt, while bottom salinity averaged 11.2 ppt, ranging from <1 ppt to 28 ppt.


Water temperatures at both depths continued to cool; surface temperatures for the week averaged 2.8°C, with a maximum value of 5.2°C, and bottom temperatures averaged 4.0°C, with a maximum value of 6.6°C. Flows of cool Blackstone River water (<3°C) continued to influence surface temperatures. Dissolved oxygen (DO) concentrations continue to remain above the hypoxia threshold (> 2.9 mg/L) at both depths. Average DO concentrations were greater than those reported last week, with surface DO averaging 13.5 mg/L, with a minimum of 12.6 mg/L, and bottom DO averaging 11.8 mg/L, with a minimum of 14.1 mg/L. Surface chlorophyll-a remained low this week, averaging 2.7 ug/L with a maximum of 4.9 ug/L. Note that tidal fluctuations and Blackstone River flow greatly influence water column DO, temperature, and salinity at this location.


Bullock Reach
Please note, the Bullock Reach sondes were removed for the 2019 monitoring season on November 19.

Week of December 8 - 14, 2019

Fixed Site Network

​Phillipsdale Landing
Water quality was good this week at Phillipsdale Landing. Please note, sondes were changed out for routine maintenance during the morning of December 10. Over the course of the week, 4.53 inches of precipitation occurred, with approximately 1.9 inches of precipitation occurring on December 9 and December 14. In response to the heavy rainfall, surface salinity decreased over the course of the week, hitting a minimum of 0.6 ppt on December 14 and averaging 4.5 mg/L this week. Average bottom salinity was also lower than the previous week, averaging 15.9 ppt and ranging from 1.0 ppt to 30.0 ppt. Water temperatures at both depths remained cool; surface temperatures for the week averaged 4.0°C and bottom temperatures averaged 5.5°C. Inputs of cool Blackstone River water following high-magnitude precipitation events resulted in decreases in surface temperature, and similar surface and bottom temperatures and salinity were observed at various times throughout the week.


Dissolved oxygen (DO) concentrations continued to remain above the hypoxia threshold (> 2.9 mg/L) at both depths. Surface DO averaged 12.9 mg/L, with a minimum of 10.8 mg/L and bottom DO averaged 10.6 mg/L with a minimum of 8.0 mg/L. Surface chlorophyll-a remained low all week, averaging 2.4 ug/L with a maximum of 4.8 ug/L. Note that tidal fluctuations and Blackstone River flow greatly influence water column DO, temperature, and salinity at this location.


Bullock Reach
Please note, the Bullock Reach sondes were removed for the 2019 monitoring season on November 19.

Week of December 1 – 7, 2019

Water Column Clarity

​Water clarity was measured at six locations in the Providence River on December 4, 2019.  Approximately 1.4 inches of rainfall occurred over the three days prior to the survey.  The average Secchi depth increased clarity since the last survey on November 4, from 2.4 m to 3.2 m.  India Point Park is the only site that exhibited decreased clarity since the previous survey, down 0.2 m.  Four sites exhibited increase clarity, the greatest of which was seen at both Conimicut Point and Ponham Rocks (up 0.93 m). The remaining site (Edgewood Shoals) had not been surveyed recently.  Water clarity ranged from 2.5 m at India Point Park to 3.6 m at Conimicut Point.  Overall, water clarity in Upper Narragansett Bay increased from north to south.

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