On Tuesday Oct 18, students from ENVS 490 (Culture and Environmental Conflict) visited Bonneville Dam east of Portland to learn about the dam and the issue of sea lion predation on threatened salmon runs.
We traveled up the Columbia River, then crossed via Bridge of the Gods to the Washington side.
The powerhouse on the Washington side of Bonneville Dam is open to visitors, and the primary site of California sea lion predation of spring Chinook (and other) fish runs…
…so down we went! (And just in time, as a power outage was imminent...ironic, no?)
We learned all sorts of engineering facts and figures: e.g., each generator can power about 30,000 homes.
Here's our guide, Jacob from the US Army Corps of Engineers.
Jacob gave us a background to this powerhouse, explaining that a whole community on the WA side was relocated to build it in the 1970s/early 1980s.
He noted that current generator turbines are far less threatening to juvenile fish runs due to design improvements.
Here's a passage for fish from one ladder to the next and out above the dam.
And here's a fish ladder getting renovated.
Speaking of fish, here's the fish counting area on the WA side…
…and occasionally a sea lion is spotted in this area as well! They are smart predators.
Why the salmon decline over time? Jacob allowed that structures such as Bonneville have made recovery difficult, but argued that the main source of trouble was fishing by Europeans, who took as much as 85% of the run in a given year.
Here, for instance, is this clever device called a fishwheel: it basically scooped up each and every fish in the river.
Here's the area just below this powerhouse where sea lion predation is most intense. Jacob said a few sea lions were spotted just today, though many more are found munching on the spring Chinook run.
After leaving the Washington powerhouse, we briefly visited the Bonneville fish hatchery, searching for Herman the sturgeon!
Others were searching too.
Here he (or a cousin) is, with a rainbow above him.
All in all, a beautiful fall day to learn about the massive transformation of the Columbia River, and the complicated dilemmas we face today when one listed species eats another!