Another notable issue is that the first duty of these reservoirs is flood control (and even if you deprioritize flood control, you need to maintain the integrity of the dam itself). That means that collecting rainwater mid season isn’t actually all that helpful—most of the dams will be doing large releases to bring their levels down over the next few days and weeks. You can’t absorb the large surge from a flooding event without unused reservoir capacity. Bad things happen when reservoirs are full with more rain on the way, eg Oroville 2017. Once the forecast dries up and snow starts to melt, the reservoirs will shift to maximizing stored volume for the dry season (vs maintaining flood control capacity for the rainy season).
The_Meek t1_j3zldn5 wrote
Reply to comment by DeadwoodNative in Northern California sees more rain while the south dries out by bluelotus214
Another notable issue is that the first duty of these reservoirs is flood control (and even if you deprioritize flood control, you need to maintain the integrity of the dam itself). That means that collecting rainwater mid season isn’t actually all that helpful—most of the dams will be doing large releases to bring their levels down over the next few days and weeks. You can’t absorb the large surge from a flooding event without unused reservoir capacity. Bad things happen when reservoirs are full with more rain on the way, eg Oroville 2017. Once the forecast dries up and snow starts to melt, the reservoirs will shift to maximizing stored volume for the dry season (vs maintaining flood control capacity for the rainy season).