Steelhead Spawning Ground Surveys, Temperature, and Discharge Monitoring in Small Tributaries of the Columbia River Upper Middle Mainstem Subbasin, 2005-2007

The primary objective of this project was to determine the distribution and abundance of summer steelhead redds, monitor temperature, and discharge in 12 small tributaries to the Columbia River in the Upper Middle Mainstem Subbasin. This area is included in the Upper Columbia summer steelhead DPS and adult steelhead distribution in these creeks has been identified as a data gap for determining abundance and spatial structure. Tributaries that were monitored as part of this study included Swakane, Squilchuck, Stemilt, Colockum, Tarpiscan (North and South Forks), Tekison, Trinidad, Quilomene, Brushy, Skookumchuck, Whiskey Dick, and Johnson Creeks. Additional information was also included for Rock Island Creek and Sand Hollow; however, they were surveyed by the Foster Creek Conservation District and the USBR, respectively. The spawning ground surveys identified steelhead spawning, live adult steelhead, or carcasses recovered in Squilchuck, Tarpiscan, Trinidad, Tekison, Quilomene, Brushy, Skookumchuck, and Johnson Creeks. However, no consistent spawning locations were identified between years in any of the creeks. The highest abundance of steelhead spawners occurred in Trinidad Creek in 2005. Eleven redds and as many as 23 adult steelhead were identified in Trinidad Creek between 31 March and 2 May 2005. Of the 3 carcasses recovered in 2005, two of them (one in Tarpiscan Creek and one in Trinidad Creek) had elastomer tags and were from a release at the Chiwawa River Hatchery. The temperature regime was variable, some creeks had a pattern of consistent temperatures (10-12 °C) throughout the spawning period (Trinidad, Skookumchuck, Whiskey Dick) combined with relatively cool conditions in late summer. Many other creeks started off cold (~5 °C in mid-late March) and warmed up to 12-14 °C by the end of the spawning period in mid May. Spring temperatures were within the preferred range for egg incubation and smoltification. Late-summer mean weekly temperatures were generally within the preferred range for juvenile steelhead rearing, though some creeks did have mean weekly maximum temperatures that exceeded 20 °C. The discharge measurements recorded in this study were not measured often enough to serve as a comprehensive evaluation of seasonal flow patterns. However, our data indicate that some creeks had relatively flashy spring runoff patterns and tended to go dry near their mouths such as Brushy, Tekison, and Tarpiscan Creeks. Other creeks (Swakane, Skookumchuck, Whiskey Dick) had relatively low flows in the spring but retained some flow during late summer. Trinidad Creek was the exception with moderate but consistent flows. The information in this study is relevant for evaluating the abundance and spatial distribution of steelhead in the Upper Columbia ESU. It should also be helpful for managers and researchers to determine if and how to include these creeks into future sampling designs for the Wenatchee summer steelhead population monitoring.