Bonneville Dam & Lake on Columbia River

December 2025

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	12814	534	96	131.10	125.10	116.60	1.10	74.40	73.40	11.60	61.80	11.60	10843	99.10
2	12665	528	96	129.60	122.60	114.20	1.10	75.10	74.00	11.60	62.40	11.60	10909	98.80
3	13441	560	96	120.60	129.60	121.20	1.00	74.20	74.30	12.00	62.30	12.00	11085	100.50
4	14329	597	96	133.00	140.00	132.00	0.60	73.50	73.60	13.00	60.60	12.90	11036	102.30
5	14375	599	96	137.20	143.20	134.80	1.00	72.50	73.20	13.60	59.60	13.50	10551	99.50
6	14463	603	96	156.60	144.60	136.30	1.00	73.90	73.90	14.20	59.70	14.20	11069	104.30
7	15236	635	96	148.80	151.80	143.40	1.00	73.60	74.50	14.50	60.00	14.50	11603	109.20
8	15097	629	96	155.20	153.20	144.20	1.40	73.80	74.50	14.90	59.60	14.80	11725	111.80
9	16321	680	96	170.20	165.20	157.30	0.50	74.30	74.70	16.40	58.30	16.40	11476	111.20
10	16747	698	96	181.50	169.50	161.60	0.50	75.50	75.30	17.20	58.10	17.20	11765	114.20
11	19395	808	96	179.70	197.70	192.50	0.50	73.70	74.60	18.40	56.20	18.30	12570	126.10
12	19196	800	96	186.60	203.60	199.20	0.50	72.00	72.40	18.50	53.90	18.30	12451	130.60
13	18597	775	96	195.60	196.60	192.20	0.50	71.90	71.90	17.80	54.10	17.60	12060	126.00
14	17957	748	96	191.90	183.90	179.50	0.50	72.80	72.40	16.70	55.70	16.50	11476	116.00
15	17994	750	96	183.70	184.70	179.10	0.50	72.50	72.50	16.60	55.90	16.40	11066	111.20
16	18623	776	96	197.40	193.40	185.40	0.50	72.90	72.90	17.30	55.60	17.00	11498	115.10
17	19275	803	96	204.80	206.80	197.40	0.50	72.80	72.60	18.40	54.20	18.10	11796	121.10
18	20907	871	96	252.60	239.60	221.90	8.80	74.10	73.10	20.30	52.80	20.10	13035	138.90
19	20355	848	96	258.70	263.70	223.20	31.60	73.50	74.00	23.10	50.90	22.80	12973	143.50
20	19484	812	96	239.00	245.00	217.10	19.00	73.00	72.70	22.40	50.30	22.10	12406	138.30
21	19765	824	96	224.90	216.90	209.80	0.50	73.80	73.00	20.50	52.50	20.30	12448	132.10
22	19762	823	96	211.30	203.30	199.10	0.50	74.70	74.40	19.40	55.00	19.30	12466	125.80
23	19895	829	96	204.70	196.70	192.50	0.50	75.50	75.60	18.60	57.00	18.50	12855	124.70
24	20480	853	96	195.70	209.70	205.60	0.50	74.10	74.10	18.90	55.20	18.70	13550	136.80
25	19723	822	96	197.60	201.60	197.60	0.50	73.70	73.50	18.20	55.30	18.00	13252	133.60
26	19919	830	96	201.90	203.90	199.90	0.50	73.40	73.40	18.30	55.10	18.10	13382	135.10
27	19829	826	96	204.30	205.30	201.30	0.50	73.30	72.90	18.30	54.60	18.10	13352	136.40
28	19978	832	96	210.80	201.80	197.70	0.50	74.30	73.70	17.80	55.90	17.60	13378	133.30
29	20256	844	96	215.30	197.30	193.30	0.50	76.10	75.10	17.20	57.90	17.00	13422	128.80
30	20450	852	96	189.40	196.40	192.40	0.50	75.30	75.50	16.90	58.60	16.80	13338	126.00
31	21031	876	96	200.70	212.70	208.60	0.50	74.10	74.00	18.10	55.90	17.90	13607	135.60

TOT	558359		2976
AVG	18012	750	96	187.43	187.27	178.93	2.50	73.82	73.73	17.12	56.61	16.97	12208	121.48

MAX	21031			258.70	263.70	223.20	31.60	76.10	75.60	23.10	62.40	22.80	13607	143.50
MIN	12665			120.60	122.60	114.20	0.50	71.90	71.90	11.60	50.30	11.60	10551	98.80