No, they don't get past the dam anymore…
"The main purpose of the Seymour Hatchery is to enhance fish stocks in the Seymour River that have been cut off from their traditional spawning grounds by the construction of the Seymour Falls Dam."
http://www.seymoursalmon.com/whatwedo.php
OK … they can get past the Cap dam, for sure, then. Otherwise my comment should be edited to "I guess they're screwed".