Election season is gaining steam here in California (as a non-swing state, things have been a little later coming than in other parts of the country, I know). So this means that the press is finally producing some in-depth coverage of ballot initiatives like Measure F in San Francisco, which would approve an $8-million study to remove and drain the Hetch Hetchy reservoir. The San Jose Mercury looked into how long it would actually take for the Hetch Hetchy valley ecosystem to recover. A lot of recovery would occur in the first 20 years after the dam removal, only with extensive help from volunteers to ensure that invasive species don’t take over the valley. Ultimately, though, it would probably take 100-150 years before a visitor to the valley would have no visual evidence of the former reservoir. Worth noting, sure.
But what about removing the dam itself? “Removing it would involve constant blasting and thousands of truck trips. A rail line might have to be built to carry away the debris.” Sounds very pristine. That blasting could even temporarily disturb parts of Yosemite, depending on how loud it is…
The real kicker is that no one understands the impact of the loss of water supply reliability. Would anyone today suggest that the proximity of Lakes Powell and Mead on the Colorado River makes at least one of those reservoirs unnecessary? Well, if not for the combined capacity of both, the Colorado River would not have been able to supply Arizona, Las Vegas, and Southern California for so long. Lake Powell has been able to mitigate the effects of long-term drought, with its storage varying from 22.5 million acre-feet in the mid-1980s to 9.9 million acre-feet in 2005. Lake Mead has similarly ranged from 25 million acre-feet in 1983 down to 10.8 million acre-feet in 2010. Yes, both are located in beautiful canyon country in the desert southwest, but these two dams have been able to sustain a loss of roughly 26.8 million acre-feet from the regional water supply between the 1980s and the mid- to late-2000s, without people having to forego drinking water. The capacity of Lake Powell alone is 24 million acre-feet…think the system doesn’t need that extra buffer?
I won’t get into the issues around power generation from water supply dams, but suffice it to say, you should be skeptical of anyone promising complete ecosystem recovery with no impact on the water supply. The other cities in the Bay Area that get their water from the Hetch Hetchy also have reason to be concerned — why should San Francisco get to determine the fate of the reservoir without any voter input from the other affected cities?