Lonely Planet review
On the southern side of the Hiram M Chittenden Locks, the fish ladder was built in 1976 to allow salmon to fight their way to spawning grounds in the Cascade headwaters of the Sammamish River, which feeds Lake Washington. Visitors can watch the fish from underwater glass-sided tanks or from above (there are nets to keep salmon from over-leaping and stranding themselves on the pavement). Sea lions munch on the salmon while the fish attempt to negotiate the ladder. Just what to do about the sea lions has stymied environmentalists, anglers and the local Fish & Wildlife Department. The best time to visit is during spawning season, from mid-June to September.
On the northern entrance to the lock area is the Carl English Jr Botanical Gardens , a charming arboretum and specimen garden. Trails wind through gardens filled with flowers and mature trees, each labeled. Flanking the gardens is a small museum and visitors center documenting the history of the locks. Free tours are offered at 1pm and 3pm daily from March to November; call ahead to arrange a time.