Background
Summer irrigation withdrawals from Catherine Creek, a tributary to the Grande Ronde River in NE Oregon, reduce stream discharge to levels below natural baseflow on an annual basis. This impacts suitable rearing habitat for ESA listed juvenile Chinook salmon and steelhead downstream of the town of Union, OR.
Additionally, low stream flows exacerbate hot summer temperatures in this reach, which are regularly >20C during summer. Despite this, we have observed very high densities of those same fish during summer snorkel surveys in that stream reach. One proposed restoration action is to purchase instream water rights to improve summer rearing habitat in this reach. Keeping more water in the creek during this critical period would likely benefit fish by reducing crowding and keeping the water slightly cooler than under the recent flow regime.
Objectives
To model changes in habitat quantity and quality available to fish in Catherine Creek below Union, OR at a variety of flows representative of a typical summer.
Primary Method
Utilize CHaMP-derived channel morphology from four sites to quantify changes in wetted area, usable wetted area and habitat suitability at flows ranging from approximately 5 – 30 cfs.