Monday, April 21, 2014

Western US Hydroelectric Generation Update: Lower Estimates

The hydro picture out west is mixed.

Stream flow forecasts continue to hold above normal in the Northwest, up slightly from last week to 105.5% of normal:

But the Sierra Nevada outlook is dry, with the statewide snow pack estimate down to 18% of normal for this date.

But this has not translated into significant declines in hydro generation in CAISO yet, with daily generation only off by about 15 GWh per day lately, versus last year.  Lower snow pack should show itself by June, as flows fall off earlier than normal.

Meanwhile the BPA generation in the Northwest is running above last year again, lately averaging about 11 GW, or about 1 GW above this time last year.

Finally, the snow pack in the Colorado River Basin has fallen, with melt beginning sooner than normal.  This is raising river levels and filling the larger reservoirs (Lake Powell and Lake Mead) more quickly than normal.