On September 27th, twenty stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers; five of these stations were also sampled for enterococci bacteria. In the five days prior to sampling, precipitation totaled 2.77 inches as recorded at TF Green.
Overall, bacteria levels were lower in both the Seekonk and Providence Rivers this week than during the previous sampling event on September 14th, likely because the first event had less time in between the rainfall and sampling. Fecal coliform levels were higher in the Seekonk River sites than in the Providence River sites (geometric means of 475 MPN/100 mL and 237 MPN/100 mL, respectively). The maximum concentration (930 MPN/100 mL) was measured at both Phillipsdale Landing and Point St Bridge.
Enterococci results had an overall geometric mean of 102 MPN/100 mL and ranged from 31 MPN/100 mL Conimicut Point to 1,354 MPN/100 mL at Point St. Bridge.
The table below lists the Rhode Island bacteria standards for primary contact and shellfishing established by the Rhode Island Department of Environmental Management (RIDEM). RIDEM defines primary contact as any recreational activities in which there is prolonged and intimate contact with water, involving considerable risk of ingesting water (e.g., swimming, diving, water skiing and surfing). Please note that the RIDEM bacteria standards are provided here for informational purposes only and are not intended to indicate official state compliance with primary contact or shellfishing standards.
Summary of Rhode Island Bacteria Standards for Saltwater Primary Contact and Shellfishing
| | Fecal Coliform | Enterococci |
| Primary Contact1 | Geometric mean ≤50 MPN/100 mL <10% of samples >400 MPN/100 mL | Geometric mean ≤35 colonies/100 mL All samples ≤104 colonies/100 mL2 |
| Shellfishing | Geometric mean ≤14 MPN/100 mL <10% of samples >49 MPN/100 mL3 | NO ENTEROCOCCI CRITERIA |
1Fecal coliform primary contact criteria applied only when adequate enterococci data are not available; 2Single sample maximum criterion for determining beach swimming advisories at designated beaches as evaluated by the Rhode Island Department of Health; 3For a three-tube decimal dilution
Table adapted from Rhode Island Water Quality Regulations (250-RICR-150-05-1); see regulations for complete details.