Snapshot of the Bay

Historical News

Week of December 29, 2019 - January 2, 2020

Surface Mapping

Data were collected on January 2, 2020 while the R/V Monitor was underway collecting nutrient samples in the Providence River estuary. The chlorophyll concentrations were good. From north to south, average chlorophyll concentrations were as follows: Upper Providence River (1.72 µg/L), Edgewood Shoals area (1.72 µg/L), Pawtuxet River area (2.39 µg/L), and Lower Providence River area (1.91 µg/L). Overall, chlorophyll ranged between non-detectable and 3.90 µg/L with an overall average of 1.95 µg/L. The chlorophyll data from this date are presented in the map below:

Dataflow 2020-01-02 small.jpg

Week of December 22-28, 2019

Water Column Clarity

Water clarity was measured at four locations in the Providence River on December 24, 2019. The three days prior to the survey were dry, with no recorded rainfall. The average Secchi depth reflected decreased clarity since the last survey on December 4, from 3.2 m to 2.1 m. Three sites exhibited decreased clarity since the last survey, with the greatest decrease (down 1.20 m) observed at Edgewood Yacht Club. The remaining site (Point St. Bridge) had not been surveyed recently. Water clarity ranged from 1.4 m at India Point Park to 2.9 m at Bullock Reach. Overall, water clarity in Upper Narragansett Bay increased from north to south.

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.