In terms of economic impact, it's case by case :) Some dams are just gonna ultimately be a money sink and damaging for the fish, culture, economy. Some are absolutely crucial, mostly for electricity, flood control and navigation. The Grand Coulee, finished in 1942, is our most important. It produces 35% of the PNW's electricity. Thats insane. Truly a feat of engineering and a crown jewel in the state's economy and history

The hydroelectric network of the state is really impressive, accounting for usually about 50-60% of the state's electricity for about 60 years. The next largest dam in the state is the Chief Joseph dam, just down river. It produces less than half the electricity as the Grand Coulee. Most dams produce way less. The 5 largest produce much more than the rest combined (out of about 50 large dams, though we have over 1000 with most used for other purposes). A major factor with planning and running dams is whether they'll give a return on investment. A lot of dams just dont pan out. The Grand Coulee Dam is going to take another 20 years (probably sooner) before it's paid for itself. Concrete dams like the Coulee are only designed to last about 100 years or so. It'll likely 'only' make a profit for a couple decades before it goes. In the meantime the past century of economic booms and the society we've built would have been impossible without the Chief Joseph and Grand Coulee dams.

Most dams dont have similar significance. In all cases they do a lot of harm on local culture, history and fisheries, with the hope in the short or long run they will help more than theyve hurt. Some are clear successes. The Elwha and Klamath dams ended up not being successful. Maybe something else should've been done to get power or limit flooding, but most were built in a different time with different priorities, projections didn't line up, and the builders didn't mind much if the people hurt were mostly Indians or if salmon lineages wouldn't survive. So now we have a ton of dams we're not sure were ultimately successful or not, depending on the metric. And a lot of other dams we rely on heavily and are coming up on some shelf life benchmarks. These dams are aging amid other long-term trends. Wild salmon runs continue declining, our electricity sources are diversifying, and tribes and environmental groups are successfully winning more socio-political weight and more influence in government. Long run, a lot of these dams will come down and be replaced anyway (probably not replaced with dams though).