Table 2. Streamflow gains and losses in the lower Clackamas River, Oregon, 1963–2006.
[Site number: See table 1. Locations of reaches and sites are shown in figure 2. Values greater than streamflow uncertainty are depicted in bold. Downstream site streamflows are adjusted for tributary or withdrawal. Noted gains and losses are from upstream to downstream sites. Abbreviations: ft3/s, cubic foot per second; +, gain from upstream site; - , loss from upstream site; (a), value from streamflow monitoring site; WY, water year (the year extending from October 1 of the previous year to September 30 of the year indicated]
Date |
Upstream site |
|
Downstream site |
Streamflow
uncertainty
(percent) |
Gain or loss |
Remarks |
Site number |
Streamflow (ft3/s) |
Site number |
Streamflow (ft3/s) |
(ft3/s) |
(percent) |
Previous studies |
08-26-1987 |
5 |
650 (a) |
|
25 |
754 |
10 |
+104 |
+16 |
Estimated tributary inflow (site numbers 11, 14, 20, and 23) equal to September 2006 measurements. |
05-14-1992 |
5 |
1,350 (a) |
|
13 |
1,200 |
10 |
-150 |
-11 |
09-01-1998 |
5 |
1,000 (a) |
|
13 |
1,060 |
10 |
+60 |
+6 |
Estimated tributary inflow (site number 11) equal to September 2006 measurement. |
09-01-1998 |
13 |
1,080 |
|
21 |
1,280 |
8 |
+200 |
+19 |
Estimated tributary inflow (site numbers 14, 20) equal to September 2006 measurements. |
Long-term streamflow data |
WY 1963–1983 average of daily means (August and September) |
5 |
943 (a) |
|
25 |
992 (a) |
10 |
+49 |
+5 |
Estimated tributary inflow (site numbers 11, 14, 20, and 23) equal to September 2006 measurements. |
WY 2001–2006 average of daily means (August and September) |
5 |
848 (a) |
|
32 |
853 (a) |
10 |
+5 |
+1 |
Estimated tributary inflow (site numbers 11, 14, 20, and 23) equal to September 2006 measurements. Includes reported withdrawals (site numbers 27, 29, and 31). |
Summary of 2006 seepage study |
09-06-2006 |
6 |
756 |
|
10 |
751 |
8 |
-5 |
-1 |
Reach A |
09-06-2006 |
10 |
751 |
|
13 |
693 |
8 |
-58 |
-8 |
Reach B |
09-06-2006 |
13 |
714 |
|
17 |
726 |
5 |
+12 |
+2 |
Reach C |
09-06-2006 |
17 |
731 |
|
22 |
830 |
8 |
+99 |
+14 |
Reach D |
09-06-2006 |
22 |
845 |
|
25 |
741 |
11 |
-104 |
-12 |
Reach E |
09-06-2006 |
25 |
742 |
|
28 |
782 |
11 |
+40 |
+5 |
Reach F |
09-07-2006 |
5 |
779 |
|
25 |
730 |
10 |
-49 |
-6 |
Reach A through E |
09-07-2006 |
25 |
772 |
|
28 |
817 |
11 |
+45 |
+6 |
Reach F |
|
First posted November 28, 2011
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