Assessment of Water Quality in James Brook,Groton, Massachusetts

Bioassessment and Chemical Testing

Goals of the Study

• Assess change in the water quality of James Brook over time

• Evaluate the probably contributions of different non-point sources of pollution on water quality and ecosystem health

• Provide baseline work that will serve to evaluate a future restoration project

The Basic Model

Bioassessment: how it works

• Diversity Indices (limiting factors)– Simple Diversity– Shannon-Weiner

• Biotic Indices– Presence/Absence of Intolerant Species– Beck’s Index (many others exist)

Beck’s Biotic Index

• Class I Organisms (Sensitive or Intolerant)• Class II Organisms (Facultative)• Class III Organisms (Tolerant)

BBI = 2 x (number of Class I Organisms) + (number of Class II Organisms)

Why aren’t Class III organisms used?

Costs and Benefits

Advantages

• Likely to identify effects of a broader range of pollutants• Likely to identify pollutants discharged over time as opposed to the

snapshot of chemical testing• Less costly

– Equipment– Training

Disadvantages

• Does not identify specific pollutants• Habitat and Ecological factors influence species distributions• Will not indicate pollutants that have no effect on non-human• Selection of groups for study is critical to valuable information

Chemical Testing

Choice of Pollutants

• Watershed Analysis• Indicator Pollutants• Field Observation

• DO• BOD• pH• Colorimetry• Turbidity• More sophisticated testing

Watershed Analysis

Indicator Pollutants

Based on sources of pollution in the watershed– Residential– Agriculture and Forestry– Industrial– Roadways– Hazardous Waste Sites

Use of the Analysis in Planning

http://www.nashuariverwatershed.org/5yr_plan/subbasins/james.htm