I haven’t been following this in detail, but have seen the photos. Yesterday(?) they thought that they could use the main spillway (with the concrete failing and built on rock). It sounds like they got more rain snowmelt than they thought so had to dump more water to keep the dam from over-topping.
So I THINK that the flooding will be due to a “controlled” release of the water using the two spillways to avoid a major failure in the dam. And that this “controlled” release will cause the flooding.
“It sounds like they got more rain snowmelt than they thought so had to dump more water to keep the dam from over-topping.”
There is NO SNOW MELT at this time of year! I had planned to go skiing this weekend, but it was going to snow followed by very low temperatures. We were going to go to Kirkwood where it was 17 degrees for the low Friday and 22 degrees for the high. Right now it’s all rainfall.
Here is a chart showing the rainfall to date and a comparison with last year and historical norms:
http://weather.sfgate.com/auto/sfgate/geo/precip/index.html