Two environmental groups characterize the controversy over the future of Capitol Lake. Capital Lake Improvement & Protection Association (CLIPA) prefers a lake and Deschutes Estuary Reclamation Team (DERT) prefers an estuary. Moreover, the local Trout Unlimited chapter took a stand in favor of estuarine restoration, for likely benefits to chinook, chum salmon and sea-run cutthroat trout.
Unfortunately, a compromise “Capitol Lagoon” idea wasn’t considered during past interagency work by Capitol Lake Adaptive Management Plan (CLAMP). This idea differs from the alternative of creating an expensive split basin to segregate fresh and saltwater areas. Instead, it promotes full-estuary flushing during winter, and approach that can improve water quality and control the invasive New Zealand mudsnail.
Presumably, CLAMP’s failure to consider a brackish-lake alternative is because they aren’t as common here as in Oregon and California. But anadromous salmonids regularly occur in stream basins with coastal lagoons there, especially if the freshwater inputs aren’t diverted for other human uses which can reduce winter flushing and worsen pollution problems.
The lagoon idea has merit in Puget Sound, too. Tacoma Metro Parks is planning such a brackish-lake restoration project for Titlow Lagoon.
CLIPA’s bottom line is that the Fifth Avenue dam forming Capitol Lake shouldn’t be breached, which is consistent with the lagoon idea, except that the lake would have saltwater rather than freshwater during summer via dam closure. This contrasts with state agencies’ former promotion of lake backflushing with seawater during summer, as the lake would instead be closed off then, when bats migrate there to feed on insects, which can also thrive in brackish waters.