Terms

Many of these terms are associated with the stream monitoring that schools like Washington Middle School students are carrying out.

Bankfull Flow

Bankfull Flow refers to the highest flow that occur almost every year usually during spring snow melt here in Montana. This flow occurs about every one and a half years and plays a major role in shaping the channel. Bankfull flow has to be estimated by looking for indications where high flow typically reaches.

Cross section profile

A cross section of the water column is measured at various points along the stream. This involves taking depth measurements across the channel and plotting them. Cross sections allows you to keep track of the water level and shape of your stream throughout the seasons and years.

DO (Dissolved Oxygen)

Except for some micro organisms, all living things require oxygen to live. Oxygen dissolves in water but exists at much lower concentrations (parts per million) those in air sre (parts per hundred). Organisms that live in aquatic systems have specialized ways of extracting oxygen from the water. Many natural factors affect the amount of dissolved oxygen in water including, temperature, flow, altitude,water chemistry, bio processes. Human actions affect dissolved oxygen levels also. Including removal of riparian vegetation, urban activities, organic waste and nutrient inputs and dams.

Flow

Flow is the volume of water that passes a point in the stream in a given unit of time. Flow=volume/time. It is estimated by measuring the velocity of the water (length/time) and multiplying it by the cross section area of the water column. When interpreting flow, it is important to keep track of the amount of precipitation that occurs and the time between the last storm and your flow measurement.

pH

pH is the measurement of how acidic or basic the water is. It is measured on a scale of 1-14. From 0-7 is considered more acidic and from 7-14 is more basic.  The pH determines what can and cannot live in the stream. 6.5-8.2 is the optimal range for most life.

Stream bed Composition

Depending on where in stream you are measuring, the composition of the streambed will vary in size. The particles that compose the stream bottom are known as the substrate. In the upper headwaters of the stream, the substrate is usually larger in size. As you go further down the stream and it gets wider and has more volume, the substrate is usually smaller.

Substrate Size classes are:

    Sand < .01 inches
    Gravel 0.1-2 inches
    Cobble 2-10 inches
    Boulder >10 inches
    Solid Bedrock

Temperature

Temperature affects the rate of all life processes including metabolism, growth, reproductive activities. Most organisms that live, in the water are said to be cold blooded (cannot control their body temperature). The temperature around them determines their body temperature. If the temperature increases or decreases too drastically,they will be stressed o even die. Different aquatic organisms have different optimal temperatures.

Wetted Edge

Where the water meets the stream bank at the time of measurement.  This is part of a cross section measurement.

Wetted Stream Depth

Wetted stream depth is the distance from the bottom of the stream to the surface of the water. This is measured across the stream to develop a cross section profile.

Biological Indicatotrs:

Ephemeroptera (Mayflies)

There are extremely wide varieties of mayflies found in standing and running water habitats. They prefer rocky, headwater type streams with cooler temperatures. Most ephemeropteras are collectors or scrapers and feed on detritus, algae, macrophytes and animal material. Some species also have the ability to decompose fine particulate organic matter.

Plecoptera (Stoneflies)

Stoneflies are associated with clean, cool running waters. Several species inhabit streams that warm up or dry up in the summer, or that are organically enriched. They inhabit different substrates according to their specific class. Some inhabit cobble or boulder surfaces, others prefer debris accumulated or leaf stream bottoms. Particular species of stoneflies are known as shredders or predators, depending on their life cycles.

Tricoptera (Caddisflies)

Caddisflies are one of the largest groups of aquatic insects. They are adapted to life out of water and also life in the water, during their immature stages. They are found in spring streams, seepage areas, rivers, lakes, marshes and temporary pools. Tricoptera have both herbaceous and predaceous feeding habits, depending on their species. Many carry their houses on their backs, making cocoon like shells out of stones leaves and other material.

Diptera (True flies)

These insects are considered the true flies and the most diverse orders of almost 120,000species. They are also one of the most diverse species in morphological and ecological characteristics. Most diptera are only breifly aquatic. They have successfully colonized in nearly every aquatic habitat, except open oceans. Habitats for diptera range from slow silty rivers, to clear torrential streams. Their feeding habits range from shredders and collectors, to gatherers and grazers, to predators. Blackflies, midges and mosquitoes are some of the well-known types of diptera.