Historical News
Fixed Site Network
Fixed Site Network
Phillipsdale Landing
Water quality at Phillipsdale Landing was fair-to-poor this week. Sondes were swapped for routine maintenance during the morning of August 31st. Rainfall this week totaled 3.95 inches at TF Green, with a majority of the rainfall (3.89 inches) occurring in the first two days of September. Impacted by the heavy rainfall at the end of the week, Blackstone River flows increased as the week progressed while remaining elevated over historical median levels. In response to the heavy rainfall, surface salinity decreased this week, averaging 3.8 ppt with a maximum value of 12.8 ppt. Bottom salinity averaged 15.4 ppt, with a maximum value of 30.1 ppt. Water temperatures averaged 22.5°C on the surface and 22.3°C on the bottom. Temperatures ranged from 19.0°C to 25.7°C at the surface and from 19.0°C to 24.8°C at the bottom.
This week, surface dissolved oxygen (DO) averaged 7.5 mg/L, with a minimum of 3.8 mg/L. Bottom DO generally increased over the course of the week, averaging 4.1 mg/L and ranging from <1.0 mg/L to 10.1 mg/L. Bottom water hypoxia (DO ≤ 2.9 mg/L) was persistent throughout the first half of the week. Chlorophyll concentrations were slightly lower than the previous week, averaging 5.2 ug/L on the surface and 3.5 ug/L on the bottom, with a surface maximum of 16.2 ug/L. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and DO at this location.
Bullock Reach
Water quality at Bullock Reach was fair-to-poor this week. Overall, salinity remained similar over the course of the week, averaging 22.4 ppt at the surface, 28.7 ppt at mid-depth, and 31.0 ppt in bottom waters. Lowest salinity (15.5 ppt) occurred in surface waters, while greatest salinity (32.3 ppt) occurred in bottom waters. Temperatures averaged 23.2°C, 23.0°C, and 22.2°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 20.5°C to 25.7°C, mid temperatures ranged from 21.2°C to 24.7°C, and bottom temperatures ranged from 20.5°C to 23.5°C.
This week, DO averaged 7.2 mg/L at the surface, 4.0 mg/L at mid-depth, and 3.4 mg/L at the bottom. Hypoxic conditions (DO ≤ 2.9 mg/L) were observed at the mid and bottom depths. The minimum DO value, 1.7 mg/L, occurred in bottom waters during the morning of August 31, which was during a period of prolonged hypoxia that lasted approximately 13 hours. Chlorophyll concentrations averaged 15.2 ug/L at the surface and 10.8 ug/L at mid-depth. The maximum chlorophyll value in surface waters was 35.4 ug/L.
Benthic Video Blog
The boat crew conducted benthic video surveys along the Bullock Reach, Edgewood, and Sabin transects on August 17, 2021. Scale lasers were used in the footage, separated by 29 cm (no lasers visible at Sabin). Visibility through the water column was fair to good this week across the transects. The bottom of all sites was characterized by sands and muds. Sabin and Bullock Reach both hosted dense patches of shell hash and rubble, as well as areas of cobbles and boulders at Sabin. All sites featured sparse patches of branched algae and Ulva, with Sabin additionally having large areas of dense filamentous algae. Dense diatom felt was also present at Sabin and Bullock Reach. Sabin and Bullock Reach experienced higher general biotic activity as noted by frequent tracks and trails, as well as observed faunal diversity. Rare benthic video sights included many small schools of juvenile black sea bass (all sites), mantis shrimp Squilla (Sabin and Edgewood), horseshoe crab (Bullock Reach), egg masses produced by the lugworm Arenicola (Edgewood), and a sea star (Sabin). Infaunal activity was highest at Sabin and Edgewood this week. Frequent large burrows (likely from Squilla), small burrows, parchment tubes, and other tube-building fauna were present at all sites. Common observations were spider crabs (Bullock Reach, image below), boring sponges (all sites), blue crab (Sabin), hermit crabs (all sites), ctenophore swarms (all sites), slipper snail Crepidula (all sites), Nassariid mudsnails (Bullock Reach and Edgewood), and large colonies of mermaid’s glove sponges and red bearded sponges (Sabin). Dense amphipod tube mats were observed at both Sabin and Edgewood.
Please note: this blog publication has been post-dated to retain chronological order as a backlog of video footage is reviewed.
Nutrients Sampling
Among the river stations sampled, total nitrogen (TN) ranged from 462 ppb (average of 2 duplicates) at Moshassuck River at Higginson Ave. to 1,530 ppb at the Warren Reservoir/Kickemuit River. Concentrations of total dissolved nitrogen (TDN) were also lowest at the Moshassuck River at Higginson Ave. site (average of two duplicates = 468 ppb), while highest TDN concentration was measured at the Ten Mile River at Central Ave. site (1,260 ppb). Additionally, dissolved inorganic nitrogen (DIN) ranged from 163 ppb at the Runnins River at River Road sampling location to 901.3 ppb at the Ten Mile River at Central Ave. site.
Among the Bay stations sampled, the highest nitrogen results occurred at Pawtuxet Cove, which had TN, TDN, and DIN results of 944 ppb, 1,140 ppb, and 613.4 ppb, respectively. The lowest TN (540 ppb), TDN (662 ppb), and DIN (115.2 ppb) occurred at the Bullock Reach Buoy site (average of duplicates reported). Chlorophyll a concentration at the Bay sites decreased from the previous week, averaging 8.68 ug/L. The maximum chlorophyll result, 16.77 ug/L, occurred in one of the duplicate samples at Bullock Reach Buoy (average of duplicates = 14.38 ug/L).
Results from nutrient sampling on September 8 and September 22 are pending analysis. The next scheduled sample date is October 6.
Fixed Site Network
Phillipsdale Landing
Water quality at Phillipsdale Landing was fair-to-poor this week. Conditions this week were mostly wet, with 1.78 inches of rainfall recorded at TF Green. Blackstone River flows remained elevated over historical median levels, based on heavy rainfall this week. Surface salinity averaged 5.4 ppt, with a maximum value of 13.1 ppt. Bottom salinity averaged 17.2 ppt, with a maximum value of 27.5 ppt. Water temperatures averaged 25.4°C on the surface and 24.3°C on the bottom. Temperatures ranged from 23.6°C to 29.1°C at the surface and from 23.3°C to 26.1°C at the bottom.
This week, surface dissolved oxygen (DO) averaged 6.3 mg/L, with a minimum of 3.9 mg/L. Bottom DO generally decreased over the course of the week and ranged from 1.7 mg/L to 6.8 mg/L; bottom hypoxia (DO ≤ 2.9 mg/L) was common. Chlorophyll concentrations were lower than the previous week, averaging 5.6 ug/L on the surface and 4.8 ug/L on the bottom, with a surface maximum of 17.7 ug/L. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and DO at this location.
Bullock Reach
Water quality at Bullock Reach was fair-to-poor this week. Sondes were changed out for routine maintenance on August 24. Salinity generally increased slightly over the course of the week, averaging 22.2 ppt at the surface, 27.3 ppt at mid-depth, and 29.9 ppt in bottom waters. Salinity ranged from 18.3 ppt to 26.1 ppt at the surface, 21.6 ppt to 29.6 ppt at the mid-depth, and 27.9 ppt to 31.2 ppt at the bottom. Surface temperature averaged 25.4°C and ranged 24.0°C – 27.8°C, mid temperatures averaged 24.3°C and ranged 23.4°C – 26.0°C, and bottom temperatures averaged 23.2°C and ranged 22.3°C – 24.2°C.
This week, DO averaged 7.5 mg/L at the surface, 4.8 mg/L at mid-depth, and 3.9 mg/L at the bottom. Hypoxic conditions (DO ≤ 2.9 mg/L) were observed at the mid and bottom depths. The minimum DO value, 2.6 mg/L, occurred in bottom waters on August 28, during a period of hypoxic conditions that lasted approximately two hours. Chlorophyll concentrations averaged 15.7 ug/L at the surface, 9.8 ug/L at mid-depth, and 1.7 ug/L at the bottom. The maximum chlorophyll value in surface waters was 119.4 ug/L.
