Like their Facebook Page
https://www.facebook.com/pages/Holtwood-whitewater-park/635767109778733?fref=nf
Releases that are scheduled for times when there is ice on the river or when very high flows occur (> 6 feet over the flashboards on the dam) will be rescheduled.
Holtwood Natural -
Surf Guide - https://drive.google.com/file/d/0B39cwBw61UyJVWNvR1dJSWVUTXc/view?usp=sharing
http://www.americanwhitewater.org/content/River/detail/id/3566/