Narrative Descriptions

Excellent: At these sites you will find a wide variety of organisms with very different body shapes and ways of making a living. There will typically be larvae of true flies (Diptera), stoneflies (Plecoptera), mayflies (Ephemeroptera), caddisflies (Trichopters), beetles (Coleoptera), dobson flies (Megaloptera), molluscs, and several types of soft bodied invertebrates. High biodiversity, or taxa richness, indicates a site with low human influences. If you observed several different types of mayflies, stoneflies and/or caddisflies (or cases) then you have a healthy site. Note: Some mayflies and caddisflies are tolerant of degradation, so the their presence doesn't necessarily indicate good water quality.

Moderate: The total number of different types of organisms declines as degradation increases. About half to two-thirds the number of taxa found at an excellent site are found in a moderate site. The primary change from an excellent site is that there will be many fewer taxa of stoneflies. Mayflies will be present, but fewer taxa. Beetles should still be present. A few types of caddisflies should be present depending on the type of degradation. Freshwater mollusks are probably absent. A single tolerant taxon may represent a large proportion of the total individuals in a sample such as baetid mayfies, simuliid flies, or scuds. The proportion of soft-bodied invertebrates increases.

Poor: The total number of taxa will be low. Most of the taxa found are soft-bodied invertebrates such as midge and fly larvae, cranefly larvae, worms, and in very poor sites, scuds and planaria. Worms are often difficult to distinguish from each other because their body shapes are similarly adapted to living in soft sediments. Stoneflies are absent entirely. The only mayflies present are probably baetids (a family of mayflies). Caddisflies may be presnt, but only one or two kinds. In general, many of the organisms are smaller than those from an excellent site sampled at the same time of the year.