Seven local river stations were sampled for nutrients on January 16, 2019. The five days prior to sampling were cold and dry, with no rain recorded in the area. The highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) results were measured in the Ten Mile River at Roger Williams Ave., with reported values of 1,870 ppb, 1,940 ppb, and 1,671 ppb, respectively. The lowest nitrogen results were measured in the Moshassuck River at Higginson Ave., at 753 ppb (TN), 787 ppb (TDN), and 635 ppb (DIN) in one of two duplicate samples collected.
Water Column Clarity
Water clarity was measured at six locations in the Providence and Seekonk Rivers on February 13, 2019. There was 0.64 inches of rainfall 3 days prior to sampling. Due to inclement boating weather, secchi measurements had not been taken since February 6th. Average water clarity 2.9 m, a slight increase from the last sampling date with 2.7 m.
Water clarity was highest at Bullock Reach with a measurement of 3.9 m. The lowest water clarity was measured at Pawtuxet Cove with a measurement of 2.4 m. There was some evidence of a north to south water clarity gradient.
Seven local and border river stations and six bay stations (surface and bottom) were sampled for nutrients on December 19, 2018. In the five days before sampling, there was 0.16 in of recorded rainfall.
Among the river stations sampled, highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) values were measured in the Ten Mile River at Roger William Ave, with reported values of 1,990 ppb, 2,100 ppb, and 1,956 ppb, respectively. The Woonasquatucket River at Manton Ave had the lowest measured values with a TN of 762 ppb, a TDN of 778 ppb, and a DIN of 663 ppb.
For the bay sites, Phillipsdale Landing had the highest concentrations of surface TN, TDN and DIN with values of 1,170 ppb, 1,040 ppb, and 943 ppb respectively. Conimicut Point had the lowest nutrient concentrations with 593 ppb for TN, 502 ppb for TDN, and 413 ppb for DIN. Chlorophyll concentrations were very low throughout the bay with a maximum of 1.8 ug/L at Phillipsdale and an overall concentration average of 1.2 ug/L.