What is Stream Assessment?

Stream Assessment was designed to be an introductory screening-level assessment method for streams. It was designed by the Nez Perce Soil and Water Conservation District (District) from a compilation of assessments, and specialized to best serve the watersheds in our area. The components of stream assessment are a combination of numerous scientific protocols. The assessment measures approximately 20 elements and is based on visual inspection of the physical and biological characteristics of the stream. Each element is assigned a numerical score relative to reference conditions and an overall score for the stream reach is calculated. A qualitative description of the stream reach is made based on overall numerical score. While stream assessment is not intended to replace more robust stream assessment protocols, it provides quick and reliable information for the use in the Districts conservation programs. It is also an educational tool through which landowners can learn about conservation of aquatic resources.

Stream Assessment Inventory Steps

1. Reaches (specific segments) of the stream within a watershed are designated. A combination of topographic maps, aerial photography, and soil data are used to determine where a reach starts and ends.
2. Once reaches are designated landownership is identified.
3. Prior to accessing private property, landowners are contacted to obtain permission. Landowners may be contacted either by phone or letter.
4. After permission is received trained District staff are sent out to the field to collect the data.
5. Once the data is collected a quality assurance is conducted to ensure that the data is accurate.
6. When the quality assurance is complete we will analyze the data and find the locations in each watershed that we would like to target our conservation work.

Components of Stream Assessment

Stream Visual Assessment Protocol (SVAP): this protocol was created by the Natural Resource Conservation Service (NRCS) to describe the general stream condition and identify potential areas of resource concerns.

Stream Channel Classification: the Rosgen Stream Assessment protocol is completed at a representative site within each reach. The following are collected: stream length, valley length, sinuosity, bankfull width, bankfull depth, floodprone width, entrenchment ration, width depth ratio, gradient, and cross-section.

Pebble Count: these are collected at riffles, and are performed by walking heal to toe perpendicular to stream flow. After each step, the pebble touching the tip of the toe will be measured. This is repeated until 100 samples have been completed.

Stream Erosion Inventory: while staff are walking the reach various erosion sites will be assessed and measured by the field crew. Bio-Assessment: at each site the field crew will collect a sample of insects, the site will then be assessed on the different types of insects found in the sample.

Cross Section: the cross section is completed at a riffle. Staff will stretch a tape from left bank to right bank and take an elevation at 1 foot increments along the section.

Plant Inventory: as the field crew are walking the reach, they will take a visual assessment of any plants they see in the reach. Taking care in noting any noxious and rare plant populations.

What’s in it for the Landowners?

The stream assessment is our preliminary step in a field assessment. The data we collect while out on your property helps to target areas of the stream that we would like to improve in the future. Some projects that we are interested in are erosion control, weed control, tree plantings, water developments, etc. This all depends on what we find upstream and downstream of your property. In other words the stream assessment is the first step in getting you, the landowner, technical and financial assistance on your property.

Landowner Participation

The stream assessment is a tool the District uses to collect natural resource information. Landowner participation is voluntary. If the landowner agrees to allow District staff on their property to collect the natural resource data, then during the inventory period District staff will walk into the property and collect the data needed for our research.

There is minimal effort required from the landowner in allowing District staff to collect data.