Research, Surveys & Monitoring

Biological Stream Monitoring supplements water quality data by determining what aquatic invertebrates are found in a stream. 

Since some invertebrates (small creatures without a backbone) are sensitive to pollutants and others are tolerant, different types are assigned point values that correspond to their pollution tolerance. A sensitive invertebrate, such as a mayfly nymph, is worth three points. A moderately tolerant type, such as a crayfish, is worth two points. A tolerant type, such as a sowbug, is worth only one point. The total score of a given stream will indicate how good the water quality is. Streams that support populations of a variety of invertebrates from all three groups score highest and are therefore of the best quality. 

Biological stream monitoring is conducted by volunteers. Those interested in assisting with stream monitoring can contact Volunteer Services or email us.

Aquatic Resource Monitoring

Every year, volunteers evaluate macroinvertebrate communities in streams across Great Parks. Macroinvertebrates are invertebrates that are large enough to see without a microscope. The presence of some macroinvertebrate groups, such as caddisflies and mayflies, can indicate good stream health, while the dominance of other macroinvertebrate groups, such as aquatic worms, can signify potential stream pollution.

Volunteers use the Pollution Tolerance Index (PTI) to generate a score for each stream, which can be used to track changes in stream health. Great Parks staff also conduct evaluations of primary headwater streams, which are tiny streams with watersheds of less than one square mile. Each stream’s physical characteristics are assessed to produce an HHEI (Headwater Habitat Evaluation Index) score. The HHEI score contributes to Great Parks’ management decisions. Additional efforts are made to evaluate lake environments and stormwater issues.

With more than 80% of our Great Parks' total acreage set aside as natural areas, managing for the widest biodiversity is a challenge. To understand the various habitats and help us prioritize our resources, Great Parks has embarked on an ambitious series of biological surveys to evaluate aquatic and terrestrial habitat. The surveys are based on using indicator species to tell us the relative health of each habitat. An indicator species is a plant or animal whose presence or absence in an area indicates certain environmental conditions. 

Assessment sites are randomly selected in each of Great Parks’ habitats, where we identify the species present and their abundance. We assign a measurable value to each site and rank them to identify those areas most in need of protection or improvement. This process will help Great Parks provide habitat for a wider variety of plants and animals. 

Great Parks staff and volunteers have conducted vegetative cover mapping of most of the Great Parks to help determine the number of acres or percentages of each habitat type found in our parks. This is helpful information when determining habitat type needs for various wildlife populations. Color coded maps can be generated for each park showing the different habitat types.