So, here we go.
As of Wednesday afternoon, rain is starting and is forecast to continue for the next 10 days, dropping about 3" total by May 9. We are 2.5" over Full Pool. The dam, at it's current 250 cfs will dump about 1" by may 9. That gives us 2.5 +3 -1 = 4.5" over Full Pool by May 9th and that doesn't account for the fact that the runoff is likely to dump MORE than the measured rainfall. 4.5" over Full Pool WILL be a problem. And dumping water downstream at the end of the rain will be a problem because they will all be full by then as well.
NOW is the time to open the dam to 500 cfs (or a bit more) and leave it that way until the rain stops and reassess. That would drop an additional 2+" by May 9 and lessen the impact. Then leaving it open at that level to deal with runoff. The goal would be to maintain Full Pool and perhaps an inch or two more as reserve for possible summer dryness.
This is proactive planning. If the rain doesn't happen as forecast, once the level drops to Full Pool, back off the dam flow.
|