Comment by foolfoolz
11 hours ago
dams have trade offs that they stop sediment outflows which can cause faster erosion. this is a big reason many california beaches have gone from mostly sandy to mostly rocky
11 hours ago
dams have trade offs that they stop sediment outflows which can cause faster erosion. this is a big reason many california beaches have gone from mostly sandy to mostly rocky
Yeah, and with California's typical topography (relatively younger mountains), there's a lot of sediment at the ready than can fill dams and render them worse than useless -- i.e., costs money, loses capacity fast, alters river and coast.
E.g.: https://en.wikipedia.org/wiki/Matilija_Dam#History
> Almost immediately after construction, the dam began silting up. The dam traps about 30% of the total sediment in the Ventura River system, depriving ocean beaches of replenishing sediment. Initially, engineers had estimated it would take 39 years for the reservoir to fill with silt, but within a few years it was clear that the siltation rate was much faster than anticipated.
There are similar sites all over the state. If you happen to live in the LA area, the Devil's Gate Dam above Pasadena is another such (but originally built for flood control, not for storage).
It's just not as easy as GP comment imagines.