Snapshot of the Bay

Historical News

Week of April 4 - 10, 2021

Fixed Site Network

Phillipsdale Landing

Water quality at Phillipsdale was good this week. Rainfall was low, just 0.1 inches recorded at TF Green on the last day of the week, and Blackstone River flows were below average for this time of year. Salinity at the Phillipsdale surface averaged 9.9 ppt and ranged from 4.2 ppt to 20.4 ppt. Bottom salinity averaged 23.3 ppt and ranged from 8.4 ppt to 30.4 ppt. Surface temperatures warmed slightly compared to last week, averaging 11.2°C and ranging from 7.6°C to 16.2°C. Bottom water temperature was similar to the prior week, averaging 9.1°C and ranging from 7.2°C to 13.2°C.

Dissolved oxygen (DO) was high at both depths, typical for this time of year, and well above the hypoxia threshold (2.9 mg/L). Surface DO averaged 11.3 mg/L, with a minimum of 9.9 mg/L, and bottom DO averaged 9.9 mg/L, with a minimum of 7.6 mg/L. Chlorophyll concentrations generally remain low, averaging 5.9 ug/L at the surface and 32.5 ug/L at the bottom. Maximum surface chlorophyll concentrations reached 145.2 ug/L, measured on April 4; spikes in surface chlorophyll coincided with low tides. Although bottom chlorophyll was elevated, the data trends did not track as expected with tide, therefore the readings are somewhat suspect. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and dissolved oxygen at this location; chlorophyll readings could also be impacted by suspended matter/particulates and macroalgae.

Bullock Reach

Bullock Reach sondes are expected to be deployed in May 2021.

Wek of May 30 – June 5, 2021

Surface Mapping

Data were collected on June 3, 2021 while the R/V Monitor was underway collecting nutrient samples in the Providence River estuary. The average chlorophyll concentrations were good to poor in the areas surveyed. From north to south, average chlorophyll concentrations were as follows: Upper Providence River (4.81 µg/L), Edgewood Shoals area (20.62 µg/L), Pawtuxet River area (6.31 µg/L), and Lower Providence River (10.15 µg/L). Overall, chlorophyll ranged between 0.97 µg/L and 56.70 µg/L with an overall average of 10.05 µg/L. The chlorophyll data from this date are presented in the map below:

Dataflow 2021-06-03 small.jpg

Week of April 25 – May 1, 2021

Water Column Clarity

Water clarity was measured at four locations in the Providence and Seekonk Rivers on April 28, 2021. In a relatively wet week, 0.62 inches of rainfall was recorded on the day of the survey and in the three days prior. Compared to the previous survey day, there was a slight decrease in water clarity across all sites measured this week. Overall, sites surveyed averaged 2.67 meters Secchi depth, compared to 2.78 meters on April 21, 2021. The lowest clarity (2.17 meters) was measured at Phillipsdale Landing, while the greatest clarity (3.23 meters) was measured at Bullock Reach Buoy. Overall, a gradient of increasing clarity from north to south was observed among all sites.

Week of April 18 – 24, 2021

Water Column Clarity

Water clarity was measured at five locations in the Providence River on April 21, 2021. In a mostly dry week, 0.07 inches of rainfall was recorded on the day of the survey and in the three days prior. Compared to the previous survey day, there was a decrease in water clarity across all sites surveyed this week. Overall, sites surveyed averaged 2.78 meters Secchi depth, compared to 3.32 meters on April 14, 2021. The lowest clarity (2.50 meters) was measured at Pawtuxet Cove, while the greatest clarity (3.10 meters) was measured at Conimicut Point Park. Overall, a slight gradient of increasing clarity from north to south was observed among all sites.

Week of April 11 – 17, 2021

Water Column Clarity

Water clarity was measured at seven locations in the Providence and Seekonk River on April 14, 2021. In a mostly dry week, 0.02 inches of rainfall was recorded on the day of the survey and in the three days prior. Compared to the previous survey day, there was a slight decrease in water clarity across all sites surveyed this week. Overall, sites surveyed averaged 3.32 meters Secchi depth, compared to 3.83 meters on April 7, 2021. The lowest clarity (2.70 meters) was measured at Phillipsdale Landing, while the greatest clarity (4.70 meters) was measured at Conimicut Point Park. Overall, a gradient of increasing clarity from north to south was observed among all sites.