A primary goal of OBMEP is to determine if there is a meaningful change in selected physical salmonid habitat parameters over time. OMBEP monitors changes to physical habitats by recording their status on a regular basis.
Transect-Based Habitat Sites
The OBMEP transect-based habitat site selection process began in 2003 using the Environmental Protection Agency’s (EPA) Generalized Random Tessellation Stratified (GRTS) design with a random sample of 300 possible sites in the Okanogan basin. Once selected, OBMEP verified these sites for access, secured landowner permissions when necessary, and reduced the list to the 150 sites spilt between the United States and Canada portions of the Okanogan basin. After the first 5 years and statistical analysis conducted on data collected from the Wenatchee ISEMP, we adjusted our site selection in the Okanogan River basin to a 4-year rotating panel design and included stratification for hydrologic, biologic, and modeling stream reach breaks for 125 sites that are sampled within a given full panel rotation.
Information is collected pertaining to presence and composition of large woody debris, riparian vegetation structure, canopy cover, human disturbance, substrate composition, embeddedness, side channel habitat, stream channel habitat types (pool, riffle, glide, etc.), and channel widths and depths.
From 2004 through 2012, OBMEP collected habitat, biological and water quality data on randomly generated, transect-based sites. Each transect-based site falls within a geographic unit of analysis called a reach in the Ecosystem Diagnosis and Treatment (EDT) model. Since it would not be financially possible to monitor transect-based sites on every reach in the Okanogan Subbasin, methods were developed in 2012 to rapidly assess stream reaches through stream walks by experts in the field. The data collected directly fills the current gaps in the EDT model as opposed to using data from an adjacent reach we know is not similar, or averaged values which are not representative of the landscape. The data collected during a Rapid Assessment is similar to that collected during a transect-based site survey but while a transect-based site survey intensively measures data along multiple transects in predetermined stream lengths, the Rapid Assessment survey relies on walking the length of an entire reach and rating environmental attributes with empirical observations and fewer measurements.
Additional data pertaining to stream bed scour and fine sediment will be collected at identified spawning locations. These discrete data collection events will be used globally to help inform the habitat model using quantifiable data.
Physical Habitat Sampling Protocols