Bonneville Dam & Lake on Columbia River

May 2026

Day of Month	Inflow kcfs	Total Outflow kcfs	Generation Flow kcfs	Spill kcfs	Midnight Reservoir Elevation	Average Forebay Elevation	Average Tailwater Elevation	Average Head feet	Project Average Tailwater	2nd Powerhouse Flow kcfs
1	247.50	244.50	82.50	149.60	73.90	73.40	19.90	53.50	19.90	79.20
2	225.20	213.20	48.90	151.90	75.00	74.20	18.20	56.00	18.20	48.90
3	229.80	235.80	73.40	150.00	74.40	74.70	19.20	55.50	19.20	70.40
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TOT
AVG	234.17	231.17	68.27	150.50	74.43	74.10	19.10	55.00	19.10	66.17

MAX	247.50	244.50	82.50	151.90	75.00	74.70	19.90	56.00	19.90	79.20
MIN	225.20	213.20	48.90	149.60	73.90	73.40	18.20	53.50	18.20	48.90