OMBEP monitors changes to physical habitats by recording their status on a regular basis. This is achieved through a suite of indicators sampled at spatially-balanced sites that are designed according to policy from the U.S. Environmental Protection Agency’s Environmental Monitoring and Assessment Program (EMAP). The EMAP design allows OBMEP to sample a broad selection of sites every year with a system of rotating panels. Annual panel sites are revisited every year while regular panel sites are revisited once every 5 years (see Figure 1).
The essential physical and environmental parameters monitored include: water quality, habitat access, habitat quality, channel condition, riparian condition, flows and hydrology, and watershed condition. Some of the key indicators within these categories include width/depth ratio, gradient, pool/riffle frequency, migration barriers, flow characteristics, water temperature, riparian disturbance, canopy cover, substrate size, and large woody debris. A complete list of the variables measured can be found in the habitat sampling protocols.
Habitat variables are usually collected by a team of two to three individuals from August to October. The habitat sites are flagged prior to data collection and snorkel surveys are conducted before habitat sampling commences. The first data collected is out-of-stream measurements (macroinvertebrates, water quality, densiometer readings, etc.). The field crew then proceeds upstream from the transect furthest downstream to collect in-river measurements (substrate size, large woody debris, gradient, etc.). This information is entered into a template on a handheld GPS unit which also plots points for each transect. At the OMBEP office, data is and analyzed for accuracy and completeness before being uploaded into the OBMEP database.
As of 2012, the number of panels was reduced from five to four, and some sites in the fifth panel were redistributed amongs the other panels or were removed. The overall number of sites was also decreased in this effort so that the same number of sites will still be done every year. This was done in response to a request from BPA to shorten the amount of time of reporting from 5 to 4 years.