The primary focus of snorkel surveys in the Okanogan River Basin is to estimate the production of juvenile summer steelhead, a species listed as endangered under the federal Endangered Species Act. Snorkel monitoring provides an estimate of the egg-to-parr survival of juvenile steelhead in the Okanogan River Basin. Additionally, estimating the abundance, species, and density of all fish at sites located throughout the Okanogan River Basin can be used as an indicator of habitat change.
Snorkel surveys are conducted at all EMAP habitat sites (see Physical Habitat Sampling), from August through September. In the mainstem of the Okanogan and Similkameen Rivers, a team of five individuals enters the water at the furthest upstream transect (transect K). The team then floats side-by-side through the site, identifying fish in each transect and marking them on wrist slates. After snorkeling, all observations are recorded in a field notebook. In the smaller, shallow tributaries, a team of two individuals snorkel the site, beginning downstream and slowly progressing upstream so as not to frighten the fish.