Interesting article in SeattlePI about tide gates, culverts and salmon
SeattlePI -- by Robert McClure
"Probably the biggest bottleneck for Skagit salmon, biologists say, is the destruction of the river's delta, where fresh water and salt water mix. Historically, young salmon could hang out here, getting acclimated to the brine of Puget Sound while hiding from predators.
But more than three-quarters of that so-called 'estuary' is gone, blocked with dikes installed to keep salt water out and create farmland. The dikes included 'tide gates' to allow rainwater to drain off the fields."