Water Velocity and Suspended Solids Measurements by In-situ Instruments in Upper Klamath Lake, Oregon

The U. S. Geological Survey conducted hydrodynamic measurements
in Upper Klamath Lake during four summer seasons (approximately
mid-June to mid-September) during 2003 to 2006. Measurements
included water current profiles made by acoustic Doppler current
profilers at a number of fixed locations in the lake during all
four years as well as from a moving boat during 2005 and
2006. Measurements of size distribution of suspended material
were made at four locations in the lake during 2004-2006. Raw
(unfiltered) data are presented as time series of
measurements. In addition, water-velocity data have been
filtered to remove wind-induced variations with periods less
than thirty hours from the measurements. Bar graphs of
horizontal and vertical water speed and acoustic backscatter
have been generated to discern diurnal variations, especially as
they relate to wind patterns over the lake.

Mean speeds of the horizontal currents in the lake range between
about 3.5 to 15 cm/s with the higher speeds at the deep
locations in the trench on the west side of the lake. Current
directions generally conform to the lake's bathymetry contours
and the water circulation pattern is usually in a clockwise
direction around the lake as established by the prevailing north
to northwesterly surface winds in the region. Diurnal patterns
in horizontal currents probably relate to diurnal wind patterns
with minimum wind speeds near noon and maximum wind speeds near
2100. Diurnal variations in vertical velocities do not appear to
be related to wind patterns; they do appear to be related to
expected patterns of vertical migration of Aphanizomenon flos
aquae, (AFA) the predominant species of blue-green algae in the
lake. Similarly, diurnal variations in acoustic backscatter,
especially near the lake's surface, are probably related to the
vertical migration of AFA.
[Summary provided the USGS.]