Region 1: EPA New England
Habitat Assessment
General Description
The habitat assessment sheets described below are utilized in evaluating the physical characteristics of a stream system. By evaluating these different stream attributes, determinations can be made or allude to whether or not causes in impairments to the water body are physical or chemical in nature.
The habitat assessment sheets are completed after team members have completed all other tests, including electro-fishing, water sampling, and macro invertebrate collections. This ensures that each team member has had the opportunity to observe the overall habitat characteristics of the stream. Each team member then ranks each stream characteristic, using the following habitat parameters:
- Epifaunal substrate/ Available cover: There is a mixture of available cover- mix of snags, submerged logs, undercut banks, cobble or other stable habitat and at a stage to allow full colonization potential.
- Substrate cover: Riffle substrate consists of gravel, cobble, and boulder particles that are 0-25% surrounded by fine sediment. Pool substrates are a mixture of substrate materials with little to no deposition of fines and gravel or cobble prevalent.
- Velocity/Depth regime: All velocity/depth regimes are present (slow-deep, slow-shallow, fast-deep, fast-shallow) and a mix of pools (large-shallow, large-deep, small-shallow, small-deep) present.
- Sediment deposition: Little or no enlargement of islands or point bars and less than 10% of the bottom affected by sediment deposition.
- Channel flow status: Water reaches base of both lower banks, and minimal amount of channel substrate is exposed.
- Channel alteration: Channelization or dredging absent or minimal; stream with normal pattern.
- Frequency of riffles: Occurrence of riffles relatively frequent; variety of habitat is key.
- Bank stability: banks stable; evidence of erosion or bank failure absent or minimal; little potential for future problems. <5% of bank affected
- Vegetative protection: More than 90% of the stream bank surfaces and immediate riparian zone covered by native vegetation, including trees, understory shrubs, or non-woody macrophytes; vegetative disruption through grazing or mowing minimal or not evident; almost all plants allowed to grow naturally.
- Riparian Vegetative Zone Width: Width of riparian zone >18 meters; human activities (I.e., parking lots, roadbeds, clear-cuts, lawns, or crops) have not impacted zone.
Significance to Biological Integrity of Stream Ecosystem
Each habitat parameter represents a different key aspect of the physical attributes that lend themselves to supporting healthy stream ecosystems. Poor ratings in any one of these parameters may be reflected in any number of the other sampling areas (ie chemistry, biology ) and point to being a causal factor in stream degradation. Physical habitat impairments are some of the most common elements contributing to the degradation of high quality stream systems in New England.