The rivers and lakes of North America provide drinking water to millions of citizens. Not only do these surface waters constitute a critical resource for communities and agriculture, but they are also home to myriad species that rely on a healthy environment to survive. Citizens have a vested interest in monitoring the health of these systems to help identify potential problems early on and educate the population at large on the potential for water supplies to be compromised.
Municipalities and corporations have the responsibility to treat and meet drinking water standards before it is made available to citizens and customers. Reducing or eliminating negative impacts on surface waters and monitoring the general health of these systems is increasingly coming under the charge of citizen action groups.
There are three general approaches to monitoring the health of freshwater ecosystems:
- Chemical and physical parameters: Testing the water for specific parameters. Several analytical tests are readily available and fairly easy to complete that can be used to evaluate the chemical and physical properties of the surface waters. Because conditions can change quickly based on weather, seasonal fl uctuations or anthropogenic activity, samples should be taken at various times during the year.
- Study of the aquatic life: Studying the presence of certain species at within a surface water body can be used to evaluate the overall health of an aquatic ecosystem. Because of their abundance and because they have been studied extensively for decades, benthic macroinvertebrates are particularly useful in calculating a biotic index – or a measure of stream, river or lake’s health based on the diversity and abundance of these organisms. Macroinvertebrates have what is called referenced tolerance values, which indicate the degree of tolerance or sensitivity of particular groups to pollution. For example, if the predominant species in a water body are known to be very tolerant of pollution, that would provide an indication that the habitat is under stress. In contrast, if the predominant species identified are known to be sensitive to stressors that would provide a good indication of a healthy aquatic ecosystem.
- Physical assessment: Visual observations of the in-stream habitat and riparian zone to assess the state and evidence of potential impacts.
The most comprehensive evaluation of a freshwater body and adjacent habitat will include all three methods.