Next month, contractors will start removing two massive dams on the Elwha River which runs through Washington’s Olympic peninsula. It is expected to bring about the largest single increase of salmon habitat and population in the Northwest.

The dam removal caps efforts started more than 20 years ago by a local tribe and visionary activists with support from Earthjustice. The dams once provided power for a paper and pulp mill, but other sources will now provide the power.

As the river returns to its historical conditions, 392,000 fish will eventually reoccupy 70 miles of habitat now blocked by the dams. This compares to about 4,000 salmon the dammed river produces annually.

Unlike many rivers in the northwest, the Elwha is still in very good condition because much of the river flows through Olympic National Park where it has been protected from logging and other development.

One of the two dams slated for removal was built on a part of the river that later became part of Olympic National Park. The dam was never legally grandfathered out of the national park and laws protecting national parks made clear the dam couldn’t legally be licensed. River restoration activists pressed this point in challenging a permit that came up for renewal in 1977. The permit was renewed on a one-year basis for years as the fight played itself out, until finally Congress got involved and legislated their removal.

The Elwha Dam story illustrates that sometimes environmental activism and use of the law can stop a bad thing from happening (like rubber stamping a dam relicensing), while shining a light on the need and opportunity to restore the environment. In this case, the legal dispute bought time until politicians took notice and addressed the problem. As Earthjustice Seattle managing attorney Todd True put it:

The take down of the Elwha River dams is like running a marathon that takes 25 years to complete. Amid the elation of heading down the homestretch to the finish line you are reminded that good things come slow, that anything is possible, and that enforcing our environmental laws actually does bring about lasting change.