As others have indicated, Tacoma has a higher energy demand during the week than on weekends, so they generate more on weekdays which results in higher streamflow.

I'm not sure I buy into the money and greed allegation, as it seems to imply that Tacoma "should" do something different than what it does. What would you have them do differently, and why?

Tacoma built and operates the dams to provide electricity. The way that makes the most sense for them is to store water when they don't need energy and generate when they do. Tacoma's interest is compromised by regulations. It would make energy and ecomomic sense for Tacoma to shut off Mayfield and dry up the lower river when they don't need the energy. Of course, they're not allowed to do that. They are required to provide minimum streamflows to protect fish migration, spawning, and rearing. Perhaps they "should" provide different flows than they do, but persuasive arguments would have to be made.

As it is, Tacoma releases more water from Mayfield during the late summer and fall than flows into the reservoirs. If Tacoma were required to run the dam "like a natural river", then we would see the lower Cowlitz flowing as little as 600 cfs at times, instead of the usual 2,000 or 2,500 cfs. That would be quite a sport to run your sled in the river at 600 cfs!

With major dams, you get some good things and you get some bad things. You get higher summer flows usually and lower peak winter flows. Cooler summer water temperature and warmer winter water temperature. Less salmon redd scour because of reduced flooding. Loss of side channel rearing habitat due to less flooding. Loss of spawning and rearing habitat and access due to dams and reservoirs. Fish usually, but not always, lose more than they gain. Fishermen, well it depends. On the Cowlitz, there aren't many wild salmon or steelhead. However, there much more likely than not, are more salmon and steelhead available to catch because of the Cowlitz mitigation hatcheries than there would be today if Tacoma had never built their dams.

Oh, and Tacoma gets electricity. Tacoma got a good deal, no question in my mind. Wild fish got a very bad deal (extinction). Fishermen got a mixed deal. More fish to catch, but a loss of wild fish and the quality experience that some anglers attach to that. A more navigable river during the summer and a less navigable and fishable one in winter.

Now you know why Tacoma changes the river flow and then some. Should Tacoma do it differently? Why or why not?

Sincerely,

Salmo g.