How to interpret the data
OARS' water quality and streamflow data is assessed in several ways. We can ask:
• Does the river or stream meet the state's water quality standards for Class B waters? (below)
• Do the nutrient concentrations exceed EPA's recommendations for unimpaired waters? (below)
• Is there enough streamflow to support fish?
• Using OAR's Stream Health Index, do the overall conditions provide healthy habitat for fish?
| Massachusetts Standards | |
| Parameter | Standard |
| Dissolved oxygen* | >= 5.0 mg/l and 60% saturation for warm water fisheries >= 6.0 mg/l and 75% saturation for cold water fisheries |
| pH* | 6.5-8.3 for inland waters |
| Nutrients* | "control cultural eutrophication" |
| Temperature* | <= 28.3 C and less than 2.8 C deviation for warm water fisheries <= 20.0 C and less than 1.7 C deviation for cold water fisheries |
| Suspended Solids** | Aquatic life: 25 mg/L maximum and <= 10 mg/l increase due to a discharge |
| Aesthetics Biocommunity** |
Primary or secondarily contact recreational use: no nuisance organisms that render the water aesthetically objectionable or unusable, "best professional judgment"; cover of macrophytes < 50% within any portion of the lake area at maximum extent of growth. |
| Fecal coliforms** | Primary contact recreational use -- Dry weather guidance: (<5 samples taken) <= 400 cfu/100ml. Wet weather guidance: dry weather samples meet and wet samples <=2000 cfu/100ml. Secondary contact recreational use -- Dry weather guidance (< 5 samples taken) <=2000 cfu/100ml. Wet weather guidance: dry weather samples meet and wet samples <= 4000 cfu/100ml. |
| *MADEP 1997 Massachusetts Surface Water Quality Standards - 314 CMR 4.00 1997. ** MADEP 2002 Massachusetts Year 2002 Integrated List of Waters, Part 1. |
|
| Reference Conditions for Ecoregion XIV Subregion 59 Streams* | ||
| Parameter | Reference condition (25th percentile of June - September data) |
Reference condition (50th percentile of June - September data) |
| Total Phosphorus (mg/L) | 0.025 | 0.050 |
| Total Nitrogen (calculated) (mg/L) | 0.44 | 0.74 |
| NO2 + NO3 (mg/L) | 0.34 | 0.43 |
| chlorophyll-a (micrograms/L) | 2.00 | 4.00 |
| * adapted from USEPA. 2000. Ambient Water Quality Criteria Recommendations: Rivers and Streams in Nutrient Ecoregion XVI. EPA 822-B-00-022. United States Environmental Protection Agency: Office of Water, Office of Science and Technology, Health and Ecological Criteria Division. Washington, D.C. December 2000. | ||
Useful references:
