The objective of this project is to monitor status and trends of the steelhead population in the Toppenish Creek watershed.  We intend to use a redd count census conducted on all known spawning habitats in the basin to obtain an index of steelhead spawner abundance.  We will attempt to use methods and models under development in the upper Columbia to arrive at an estimate of steelhead adult spawner  abundance.  Abundance estimates will incorporate redd counts, information on redd life, regional data on the number of redds per female (or information obtained from the Yakima VSP 201003000 monitoring radio tracking study), annual Yakima basin sex ratios observed at Prosser dam, and mark-resight data collected to evaluate observer efficiency.

We will evaluate the steelhead abundance estimate by using radio tracking data collected under the Yakima VSP project during years 2011-2013.   Prosser Dam Counts will be partitioned to individual tributaries including Toppenish Creek based on proportions of a representative sample radio tagged at Prosser and tracked to their final spawning location.  When Genetic Stock Identification (GSI) data collected from Prosser dam and analyzed as part of the Yakima VSP project becomes available for the Yakima MPG we will use this information to compare estimates.  Like the radiotracking study, GSI data will be used to disaggregate the Prosser dam count into the four distinct populations (including Toppenish).  If spawner estimates from these different methods differ substantially we will consider constructing a total upstream/downstream resistance board weir at the mouth of Toppenish Creek the following year (summer 2012).

We will operate a rotary screw trap continuously capturing the entire spawning season to obtain an estimate of steelhead juvenile outmigration.  In addition to monitoring the Toppenish Creek  steelhead population viability, we will use this information in the development of an IMW to evaluate restoration activities planned in the basin.