Here's a no-brainer: If you're building a dam across the "Eel" River, expect that you'll likely have to deal with some eels.
The hydroelectric dam on the south fork of the Eel River promised to finally bring a new source of electricity to Sonoma and Marin County, where the "juice" was notoriously flaky. This power from Mendocino County was expected to be more reliable, more affordable (electricity was about 25 times more expensive than it is today) and available in more areas; in a deal brokered by James Wyatt Oates, new lines would carry service "in all directions throughout the county." Only one obstacle stood in the way of all that goodness - and that squirmy obstacle numbered in the many thousands.
So great were the numbers of eels trying to return to their upstream spawning grounds that workers first hauled them out of the water with pitchforks. That either proved too much work or eels continued to slip through and gum up the works, so they decided to electrocute the eels (as well as anything else in the river that was nearby). "Now great loads of dead eels are hauled away and buried every few days."
Those "eels" were not eels at all (or a fish, either): They were Pacific Lampreys, which can grow up to 30" long and like the salmon, must return to fresh water spawning grounds to breed (MORE INFO). They once outnumbered salmon by 100+ to 1, and their vast populations served as a decoy for spawning salmon from hungry seals, bears, and humans. “They may be the prey of choice for just about everything, except - as my tribal elders tell me - the white people. Every creature loves lampreys because of the high fat content,” a fishery biologist recently told a Washington state newspaper. Although whites considered it a "trash fish," tribes in the Northwest used its oil for earaches and the skin as bandage wraps, as well as eating them it's said to taste like a cross between a pork chop and mackerel). The Pacific Lamprey is still mostly ignored by researchers, and is now endangered in the Western U.S.
KILL MANY EELS BY ELECTRICITY
The Snow Mountain Power & Water Company is having great difficulty with the unusual number of eels in the river this season. The wiggling fishy mass gets into the power plant through the canal. Great piles of eels have been removed with pitchforks. Finally the electricians have hit on the novel plan of electrocuting them as they entered the canal, and now great loads of dead eels are hauled away and buried every few days. The eels are supposed to have been attracted by the great run of young trout of which they are very fond. The Fish Commission is much pleased with the solution of the difficulty as it does away with enormous quantities of the worst enemy the trout have in the district.- Press Democrat, May 17, 1908