Bonneville Dam & Lake on Columbia River

September 2026

Day of Month	Total Generation MWh	Average Generation MW	Station Use MWh	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 Total MWh	2nd Powerhouse Flow kcfs
1	8841	368	96	86.30	90.30	75.20	2.80	75.60	75.70	9.30	66.40	9.20	8547	72.70
2	8690	362	96	92.10	88.10	73.30	2.40	76.00	75.80	9.10	66.70	9.00	7178	61.00
3	8605	359	96	89.70	86.70	72.00	2.30	76.40	76.00	8.90	67.10	8.80	6330	53.50
4	9829	410	96		97.80		2.30			9.60		9.50	7616	64.90
5	7758	323	96	76.70	78.70	64.00	2.30	76.10	76.10	8.20	67.90	8.00	5502	45.80
6	7468	311	96	73.90	75.90	61.20	2.30	75.90	76.10	8.00	68.10	7.80	5178	43.00
7				70.80	72.80	58.10	2.30	75.70	75.70	7.80	67.90	7.60		40.30
8				83.20	80.20	65.50	2.30	76.00	75.80	8.20	67.60	8.00		47.40
9				78.60	79.60	64.90	2.40	75.90	76.00	8.20	67.80	8.10		46.60
10				85.10	82.10	67.40	2.40	76.10	75.90	8.60	67.30	8.50		48.90
11				73.40	76.40	61.70	2.40	75.90	75.90	8.40	67.50	8.30		55.50
12				76.20	77.20	62.50	2.30	75.80	75.60	8.40	67.20	8.20		62.50
13				75.80	76.80	62.10	2.30	75.70	75.50	8.40	67.10	8.20		62.10
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TOT	51191		576
AVG	8532	355	96	80.15	81.74	65.66	2.37	75.92	75.84	8.55	67.38	8.40	6725	54.17

MAX	9829			92.10	97.80	75.20	2.80	76.40	76.10	9.60	68.10	9.50	8547	72.70
MIN	7468			70.80	72.80	58.10	2.30	75.60	75.50	7.80	66.40	7.60	5178	40.30