Jule Schultz, the Spokane Riverkeeper Technical Lead, sampled water near the mouth of both Hangman Creek and California Creek on 2/10/2015 after the heavy rains of the weekend.  California Creek, a small tributary of Hangman Creek, flows from some of the most ecologically intact watershed in the Hangman basin.  Lined with streamside woody vegetation, this stream contains small populations of trout, although it flows through working farmland and forestland in the upper reaches.

The mouth of California Creek.

Hangman Creek from the 11th bridge, flowing at 2,100 cfs on 2/10/15.

Hangman Creek on the other hand has had most of its streamside vegetation ripped out from farming activities.

stream

Comparing the two samples, the results are striking, at least in terms of water clarity (turbidity).  Visibility was 5.9 cm in Hangman Creek and 50.9 cm in California Creek.  Measured scientifically, the results are even greater, with Hangman Creek over 100 times more turbid than California Creek (210 ftu vs 2 ftu).  Trout begin to look for refuge from the dirty water at 30 FTU.  So it seems clear to me why trout would choose to live in California Creek.

California (left) and Hangman (right) Creek water samples.  The difference is clear.