USGS Scientific Investigations Report 2010–5016 Development of an Environmental Flow Framework for the McKenzie River Basin, Oregon

Table 13. Pre- and post-dam streamflow statistics from measured and estimated daily mean streamflow for McKenzie River, Oregon.

[1-day max.: Median of 1-day maximum annual flows; 7-day min.: Median of 7-day averaged minimum annual flows. Indicators of Hydrologic Alteration (IHA) significance count value: Output from the IHA software package and is equivalent to a p value for significance. Reaches 8 and 10 statistics computed from Leaburg and Walterville canal bypass river flow data only. Pre-dam period data were unavailable for Reaches 8 and 10. Abbreviations: na, not available; Unreg, statistics based computed unregulated daily flows from the U.S. Army Corps of Engineers; Reg, statistics based on simulated regulated daily flows from the U.S. Army Corps of Engineers; na, not applicable]

Reach No.	Streamflow-gaging station No.	Period of record (water years)		1-day max.	7-day min.	Mean streamflow	Standard deviation
1	14158850	Pre-dam	1936–1962	3,111	614	1,003	440
		Post-dam	1963–2008	2,465	572	1,007	405
		Percent change		-21	-7	0	-8
		IHA significance count value		.22	.11	na	na
2	14159110	Pre-dam	1936–1962	8,095	1,537	2,603	441
		Post-dam	1963–2008	7,780	1,492	2,624	441
		Percent change		-4	-3	1	0
		IHA significance count value		.64	.46	na	na
3	14159500	Pre-dam	1936–1963	6,321	214	853	860
		Post-dam	1964–2008	4,410	265	821	716
		Percent change		-30	24	-4	-17
		IHA significance count value		.00	.00	na	na
		Pre-dam	1936–1963	6,321	214	853	860
		Unreg	1964–2008	5,318	252	829	788
		Percent change		-16	18	-3	-8
		IHA significance count value		.25	.00	na	na
		Pre-dam	1936–1963	6,321	214	853	860
		Reg	1964–2004	4,303	300	830	664
		Percent change		-32	40	-3	-23
		IHA significance count value		.00	.00	na	na
4	na	Pre-dam	1936–1962	14,490	1,809	3,526	2,010
		Post-dam	1963–2008	10,210	2,053	3,510	1,615
		Percent change		-30	13	-0	-20
		IHA significance count value		.00	.00	na	na
5	14162200	Pre-dam	1936–1968	4,982	23	455	700
		Post-dam	1969–2008	3,010	47	459	563
		Percent change		-40	102	1	-20
		IHA significance count value		.00	.00	na	na
		Pre-dam	1936–1968	4,982	23	455	700
		Unreg	1969–2008	5,125	25	467	691
		Percent change		3	9	2	-1
		IHA significance count value		.49	.18	na	na
		Pre-dam	1936–1968	4,982	23	455	700
		Reg	1969–2004	3,000	50	470	648
		Percent change		-40	116	3	-7
		IHA significance count value		.00	.00	na	na
6	na	Pre-dam	1925–1962	23,320	1,522	3,860	3,011
		Post-dam	1963–2008	13,720	1,912	3,988	2,433
		Percent change		-41	26	3	-19
		IHA significance count value		.00	.00	na	na
7	14162500	Pre-dam	1925–1962	23,800	1,553	3,939	3,067
		Post-dam	1963–2008	14,000	1,951	4,070	2,491
		Percent change		-41	26	3	-19
		IHA significance count value		.00	.00	na	na
		Pre-dam	1925–1962	23,800	1,553	3,939	3,067
		Unreg	1963–2004	21,240	1,561	4,091	3,109
		Percent change		-11	1	4	1
		IHA significance count value		.37	.89	na	na
		Pre-dam	1925–1962	23,800	1,553	3,939	3,067
		Reg	1963–2004	14,230	1,950	4,095	2,416
		Percent change		-40	26	4	-21
		IHA significance count value		.00	.00	na	na
8	14163150	Post-dam	1989–2008	14,600	1,010	2,608	2,791
9	na	Pre-dam	1925–1962	27,380	1,786	4,532	3,535
		Post-dam	1963–2008	16,110	2,245	4,683	2,857
		Percent change		-41	26	3	-19
		IHA significance count value		.00	.00	na	na
10	14163900	Post-dam	1989–2008	15,220	1,044	2,828	3,026
11	14164900	Pre-dam	1936–1962	29,810	1,482	4,616	4,016
		Post-dam	1963–2008	18,040	1,791	4,495	3,236
		Percent change		-39	21	-3	-19
		IHA significance count value		.00	.00	na	na
12	14165500	Pre-dam	1936–1962	34,700	1,744	5,581	4,987
		Post-dam	1963–2008	22,200	2,131	5,382	4,038
		Percent change		-36	22	-4	-19
		IHA significance count value		.01	.00	na	na