Most west coast hydro comes from the Pacific Northwest, in the Bonneville Power Administration. Thusfar in '19, output has been far far below 2018, averaging 7.7 GW vs. 11.0 GW in '18. That's about 2/3 of a BCFD in gas equivalent.
Snowpack suggests these reduced flows will continue. As of 4/18, Washington snowpack was 82% of average, while last year on this date it was 128%.
There is less hydro potential in California, but snowpack is much healthier. It sits at 199% of normal, vs. 73% last year.
See the snowpack table from the NRCS here.