News – Page 17 – Narrabay

February 19-25, 2023

Nutrient samples were collected from fifteen local and border river stations, and eight bay stations on February 22nd, 2023. The Edgewood Shoal bay station was sampled at surface and bottom while all other bay stations were only sampled at the surface. In the five days prior to sampling, 0.42 inches of rainfall was recorded at T.F. Green.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed at Ten Mile River at Central Ave. The TN, TDN, and DIN were 2,680 ppb, 2,670 ppb, and 2,410 ppb respectively. The lowest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed at Palmer River at Route 6. The TN, TDN, and DIN were 606 ppb, 387 ppb, and 171.9 ppb, respectively.

Among the bay stations sampled, the highest surface TN, TDN, and DIN concentrations was observed at Phillipsdale Landing as 1,740 ppb, 1,610 ppb, and 1,326 ppb, respectively. The lowest surface TN (551 ppb), TDN (289 ppb) and DIN (166 ppb) were observed at Bullock Reach Buoy. Chlorophyll a concentrations at the bay stations have increased (averaging 5.54 ug/L) since all these sites had previously been sampled in January. The maximum result (10.65 ug/L) occurred at Bullock Reach Buoy.

Data from additional sampling dates (typically every two weeks) are pending analysis and writeup

February 19-25, 2023

Surface chlorophyll data were collected on February 22, 2023 while the R/V Monitor was underway collecting nutrient samples in the Providence River estuary. The average chlorophyll concentrations were categorized as good in the areas surveyed. Overall, chlorophyll ranged between 0.54 and 5.19 µg/L with an average of 1.95 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

February 12-18, 2023

Phillipsdale Landing

The surface sonde deployed on February 7th failed to log data internally, and so there is a data gap until DCP communications were restored this week on February 15th. Unfortunately, restoration of this connection resulted in lost depth data for both sondes through the end of the deployment on February 23rd. Data in this week’s summary should be interpreted with caution due to the gap in surface data and lack of depth data to confirm sonde positioning at both depths.

Weather conditions this week were mostly dry, with just 0.25 inches of rainfall on February 17th and trace rainfall on the 13th and 16th. Blackstone River flows continued to decline all week and fell below the 18-year median flow rates for this time of year. Surface salinity from the latter half of the week averaged 7.4 ppt and ranged from 2.0 ppt to 20.3 ppt. At the bottom, salinity averaged 20.6 ppt and ranged from 5.2 ppt to 29.8 ppt. Temperatures at the surface (latter half of the week) averaged 6.4°C, ranging 4.4°C – 8.1°C. At the bottom, temperatures averaged 5.4°C and ranged 4.6°C – 7.0°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold of 2.9 mg/L throughout the week. Surface DO (latter half of the week) averaged 11.3 mg/L and ranged 10.1 – 12.4 mg/L. Bottom DO concentrations averaged 9.9 mg/L and ranged from 8.8 mg/L to 12.3 mg/L. Chlorophyll readings generally remained low, averaging 0.8 ug/L at the surface (latter half of the week) and 2.9 ug/L at the bottom. Maximum chlorophyll at the surface reached just 6.8 ug/L in the data available this week. At the bottom, chlorophyll hit an isolated maximum of 25.1 ug/L on February 17th, though this does not appear to be related to phytoplankton activity as there were no concurrent changes to pH or DO. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Bullock Reach sondes will be deployed later this spring for the 2023 monitoring season.

February 5-11, 2023

Phillipsdale Landing

Sondes were swapped for routine maintenance on the morning of February 7th. The surface sonde continued to exhibit unusual buoyancy as began with the cold snap on February 3rd; for this week, approximately 27 hours of surface data were excluded from February 5th and 6th when the sonde was out of position. In addition the new surface sonde deployed on February 7th failed to log data, and so there is a data gap from this point through the end of the week. For these reasons, there are very limited surface data included in the following summary.

Weather conditions this week were mostly dry, with just 0.05 inches of rainfall on February 7th and trace rainfall on the 8th and 9th. Blackstone River flows continued to decline all week, but overall remain above the 18-year median flow rates for this time of year. Surface salinity from the limited data available early in the week averaged 5.0 ppt and ranged from 1.4 ppt to 9.3 ppt. At the bottom, salinity averaged 18.4 ppt and ranged from 3.6 ppt to 29.5 ppt. Temperatures at the surface (limited data) averaged 1.7°C, ranging -0.4°C – 2.9°C. At the bottom, temperatures averaged 3.8°C and ranged 0.5°C – 6.0°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold of 2.9 mg/L throughout the week. Surface DO (limited data) averaged 13.0 mg/L and ranged 12.3 – 14.2 mg/L. Bottom DO concentrations averaged 11.0 mg/L and ranged from 9.2 mg/L to 14.2 mg/L. Chlorophyll readings remained low, averaging 1.5 ug/L at the surface (limited data) and 7.4 ug/L at the bottom. Maximum chlorophyll at the surface reached just 2.3 ug/L in this limited dataset. Chlorophyll at the bottom was elevated early in the week, though this does not appear to be related to phytoplankton activity as there were no concurrent changes to pH or DO; the spikes may have been related to the very cold temperatures or sediment interference. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Bullock Reach sondes will be deployed later this spring for the 2023 monitoring season.

February 5-11, 2023

Nutrient samples were collected from one bay station and seven local river stations on February 8th, 2023. Bay station Phillipsdale Landing was sampled at the surface and the bottom. In the five days prior to sampling, 0.05 inches of rainfall was recorded at T.F. Green.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed at Ten Mile River at Roger Williams Ave. The TN, TDN, and DIN were 2,310 ppb, 2,370 ppb, and 2,023.9 ppb respectively. The lowest TN, TDN, and DIN were observed in the duplicates at Moshassuck River at Higginson Ave. The TN, TDN, and DIN were averaging 877 ppb, 878 ppb, and 740.6 ppb, respectively.

The Phillipsdale Landing station had TN, TDN, and DIN concentrations of 1,500 ppb, 1,350 ppb, and 1,142 ppb, respectively. Chlorophyll a concentration has decreased at Phillipsdale Landing (0.566 ug/L) since it was last sampled in January. The maximum result (10.65 ug/L) occurred at Bullock Reach Buoy.

Data from additional sampling dates (typically every two weeks) are pending analysis and writeup.

January 29-February 4, 2023

Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was good this week. Weather conditions were mostly dry, with just trace rainfall on January 29th and February 1st, and minor snowfall on January 31st. Blackstone River flows declined over the course of the week. Surface salinity averaged 1.7 ppt and ranged from 0.2 ppt to 7.7 ppt. At the bottom, salinity averaged 11.4 ppt and ranged from 0.3 ppt to 29.7 ppt. February 3rd and 4th saw a blast of arctic air temperatures, and the waters responded by cooling dramatically at the end of the week. Temperatures overall averaged 4.0°C at the surface, ranging -0.3°C – 6.5°C. At the bottom, temperatures averaged 4.4°C and ranged 0.0°C – 6.0°C. During the cold snap, the surface sonde went out of position, possibly due to ice formation impacting sonde buoyancy; approximately 19 hours of surface data were excluded from this summary when the sonde was out of position.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold of 2.9 mg/L throughout the week. Surface DO averaged 12.9 mg/L and ranged 12.0 – 14.8 mg/L. Bottom DO concentrations averaged 11.8 mg/L and ranged from 8.4 mg/L to 14.2 mg/L. Chlorophyll readings remained low, averaging 2.0 ug/L at the surface and 9.9 ug/L at the bottom. Maximum chlorophyll at the surface reached just 8.4 ug/L this week. Chlorophyll at the bottom was elevated late in the week, though this does not appear to be related to phytoplankton activity as there were no concurrent changes to pH or DO; the spikes may have been related to the very cold temperatures or sediment interference. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Bullock Reach sondes will be deployed later this spring for the 2023 monitoring season.

January 22-28, 2023

Phillipsdale Landing

Sondes were swapped for routine maintenance on the morning of January 24th. Overall, water quality at Phillipsdale Landing was good this week. Weather conditions were rainy, including 0.34 inches on January 22nd, 0.92 inches on January 23rd (included some snow), 0.75 inches on January 25th, and 1.09 inches on January 26th (all as recorded at T.F. Green). Blackstone River flows were heavy all week in response to the precipitation, resulting in decreased salinity at Phillipsdale, particularly at the end of the week. Over the whole week, surface salinity averaged 2.0 ppt and ranged from 0.2 ppt to 9.9 ppt. At the bottom, salinity averaged 9.5 ppt and ranged from 0.2 ppt to 28.6 ppt. Temperatures cooled this week, averaging 3.8°C at the surface and ranging 2.3°C – 5.3°C. At the bottom, temperatures averaged 4.4°C and ranged 2.6°C – 5.9°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold of 2.9 mg/L throughout the week. Surface DO averaged 13.4 mg/L and ranged 12.0 – 14.2 mg/L. Bottom DO concentrations averaged 12.4 mg/L and ranged from 9.4 mg/L to 14.6 mg/L. Chlorophyll readings remained low, averaging 1.7 ug/L at the surface and 2.5 ug/L at the bottom. Maximum chlorophyll at the surface reached just 3.0 ug/L this week. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach

Bullock Reach sondes will be deployed later this spring for the 2023 monitoring season.

January 22-28, 2023

Nutrient samples were collected from 15 local river stations on January 25th. Bay sampling was cancelled due to a small craft advisory. In the five days prior to sampling, 1.48 inches of precipitation were 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 = 1,930 ppb, TDN = 1,980 ppb, DIN = 1,640 ppb). The lowest TN was observed at Palmer River @ Rt. 6 (TN = 624 ppb). The lowest TDN was measured in one of the duplicate samples from Coles River @ Milford Rd. (649 ppb), while the other duplicate was slightly higher at 657 ppb; TDN was similarly low at Palmer River @ Rt. 6 (652 ppb). The lowest DIN was observed at Coles River @ Milford Rd. (DIN = 221 ppb, average of duplicates).

Data from additional sampling dates (typically every two weeks) are pending analysis and writeup.

January 15-21, 2023

Water clarity was measured at six locations in the Providence River and Seekonk River estuaries on January 18. Rainfall totaling 0.52 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.7 meters, compared to 3.3 meters on the previous survey (January 10). The lowest clarity this week (2.6 meters) was measured at India Point Park, Phillipsdale Landing, and Pomham Rocks, while the greatest clarity (2.9 meters) was measured at Bullock Reach and Conimicut Point. There was a general north-to-south gradient of increasing water clarity among the sites this week.

January 15-21, 2023

On Wednesday, January 18th, the crew of the R/V Monitor was out on the upper Bay collecting bacteria samples, taking Secchi Disk water clarity measurements, and conducting real-time surface mapping of water quality parameters, including dissolved oxygen, chlorophyll, water temperature, salinity, and pH, all in an effort to document water quality improvements associated with NBC construction projects. Jeff captained the boat while monitoring professionals Amanda and Daryll collected the samples and data. It was mostly cloudy but relatively warm with calm waters. The featured photo taken was of the Pomham Rocks Lighthouse.