Updated: Steelhead Emergence Forecast

Posted on Sunday, April 12th, 2015

Using temperature data that we collected at several locations, we have estimated the amount of Steelhead that have already emerged from the gravel AND we have forecasted when the rest of this year’s brood will emerge.  While in the gravel, the Steelhead eggs and Alevin are very sensitive to temperatures.  Once they emerge, they are both less sensitive and able to seek cooler water.


This graph shows that as of 4-8-15, we estimate that about 88% of the Steelhead have emerged.  This emergence rate is a bit slower than when last estimated (about a week ago) because water temperatures have been cooler.  However, the cooler water temperatures also means that the survival rate of the emerging Steelhead will be higher.  We estimate that we should hit about 90% emergence on Moday 4-13-15 and 99% around  April 22nd.SH emergence 4-8-15Additional notes:  We have estimated and forecasted emergence using measured water temperatures and redd surveys at three different river reaches:

  • Lower (L):  Between Watt Ave and William Pond
  • Middle (M): Around Roosmoor Bar
  • Upper (H): Around Sunrise

Each point on the graph represents a group of redds that emerge at the given date.  The code next to each point tells the location (river reach) and number of those emerging redds.


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PostedSunday, April 12th, 2015