An important measure of stream health is its biological community. What type of organisms live there? How diverse is the community? How healthy are the individual organisms? These are important indicators of the overall health of the stream. We collect information on all stages of the food chain in streams, including the algal or periphyton (attached algae) community, fish, and aquatic insects. See what is in streams in your area with our Interactive Stream Health Map.

ALGAE

An important measure of aquatic ecosystem health is the status of its algal community. We mainly concentrate on the density of the Periphyton (attached algae) community. Sometimes we also consider what types or species of algae are dominant in the stream to help us determine what might be negatively affecting the water quality. Nutrients from animal or human waste, or fertilizer, can cause increased algae growth. In Oklahoma streams, we most commonly see blue-green, common green, and filamentous algae.

FISH

To determine the overall health of a stream, it is important to consider the type and health of fish that live there. Certain fish are more or less tolerant of pollution than other fish. While fish tolerant of pollution are often found in streams with excellent, good, or poor water quality, sensitive fish are intolerant of pollution and cannot thrive in streams with poor water quality. Therefore, sensitive fish are only found in streams with excellent water quality. It is often the absence of sensitive species, or a high ratio of tolerant to sensitive species, that indicates poor water quality.  We collect fish from each monitored stream every one to five years by seining and/or electroshocking in a 400-meter reach of the stream. One of every species of fish caught is kept as a sample specimen and all others are counted and released.

MARCOINVERTEBRATES

Another important measure of aquatic ecosystem health is the status of its aquatic insects, called benthic macroinvertebrates.  We measure the type and densities of benthic macroinvertebrates (aquatic insects) that live in the stream. These organisms are fish food, and so are very important in determining what else can live in a stream. Certain species are indicators of poor water quality. Others indicate pristine water quality. By looking at what kinds of “bugs” live in the water, we can tell whether or not the community is well balanced and diverse, which is a good indicator of pristine or excellent water quality. OCC follows Standard Operating Procedures (SOPs) based on EPA’s Rapid Bioassessment Protocols (RBP) to collect and analyze this data. Benthic macroinvertebrate collections are usually made twice a year. Biological communities are assessed according to procedures outlined in an EPA approved SOP.

Western Oklahoma

Northeastern Oklahoma

Southeastern Oklahoma

Assessment of Stream Macroinvertebrates

Indicators of Poor Water Quality	Indicators of Fair Water Quality	Indicators of Good Water Quality
Blackfly Larvae	Cranefly Larvae	Caddisfly
Leech	Crayfish	Gilled Snail
Midgefly	Damselfly	Mayfly
Midges	Dobson Fly (helgramite)	Stonefly
Pouch Snail	Dragonfly
Pulmonate Snail	Riffle Beetle
Worm	Scud

Stream aquatic communities are assessed along with stream habitat and stream water quality to determine the stream’s overall health.