Beaver Flows:
1. 6/1/1878-mid 1909: estimated from flows at The Dalles and Albany on the Willamette.
For 6/1/1878 to 4/30/1888, about 40% of the daily Albany observations are present. No
Albany data are available from 5/1/1888 to 10/31/1892. October 1893 and OctoberDecember 1894 data are also missing. Albany gaps were filled using a regression
relationship between monthly Corvallis or Albany precipitation (Portland in 18786/1880) and flow, 1895-1912. Albany data were then interpolated to daily, using the
observations whenever these were available. Flows for the 4 Feb 1890 freshet are taken
from the 1881 freshet, but scaled to the known peak 1890 flow. Albany flows were then
delayed and scaled up to levels appropriate to Portland. Bonneville flows were estimated
from those at The Dalles, based on a monthly regression based on 1928-38 values. Flows
for other Westside tributaries were based on correlations between Albany and the
tributary in question. These are generally not very strong, so the results are not terribly
accurate.
2. Albany and Beaver files ending in “new” use a new method for 1889-92 and for the gaps
in 1893 and 1894: flows are modeled on daily precip at Corvallis using lags to 5 days.
The 1890 freshet is still interpolated from 1881, however.
3. From 1909 to mid-1928, additional tributaries were brought in as they became available,
so values for Bonneville and for the westside become more realistic. From 7/1/1928 to
6/28/1991 (except for 1968-70) Beaver flows are routed from Portland, all westside
tributaries and Bonneville. Up to 10/1/1961, Bonneville flows are routed from The Dalles
and tributaries, using the values compiled in the BPA “2000-Level Modified Flows”.
This volume uses observed Bonneville flows from 1961-1990, but these are inaccurate.
Because 1961-1991 Bonneville flows are not usable, Bonneville flows were routed from
The Dalles and tributaries.
4. For 5/1/1968 to 6/30/1970 and 6/281991 forward, observed flows at Beaver are used.
The following discussion is now outdated, but these files are in the bits and pieces subdirectory
1. 1912-1950: Daily Beaver flows are routed from The Dalles and 10 or 11 other stations
including Salem on the Willamette using an algorithm due to Orem (1968); not all
relevant stations are available, however, until ca. 1927.
2. 1951-1991: Daily Beaver flows are routed from Bonneville and other stations including
Salem on the Willamette using a modification of the Orem (1968) method. Using flows at
Bonneville instead of The Dalles eliminates several stations. Also, 5/1/1968 to 6/30/1970
are taken from USGS observations at Beaver.
3. 1991-2004: after 6/28/2004, daily Beaver observed flow is available from USGS.