Summary

• Temperature profiles suggest a broad range of predicted emergence times among study reaches in the upper Yakima River Basin.

• Differential developmental rates appear to be, in part, attributable to temperature related factors; suggesting the need to evaluate time of emergence at a reach scale.

• Survival and developmental stage at 900 ATU was not significantly different between egg boxes and emergence traps, suggesting they should be appropriate for use in evaluating emergence time over a larger spatial scale.