U.S. Bureau of Land Management
A Salty Oasis
Ancient Lake Chewaucan
A cooler, wetter climated engulfed North America 10,000 years ago.
Rains and run-off filled more than a hundred shallow depressions in
the western United States. These "great basins," lakes without outlets,
covered much of the arid lands of Utah, Nevada, and Oregon.
Lake Abert was once part of a large basin known as Lake Chewaukan
(shoe-wa-kan) that covered 460 square miles, about the size of
San Francisco Bay. The surface was 260 feet above Lake Abert and
over 7 times larger. Receding and sometimes rising, shorelines from
the ancestral lake are still visible on the rocky slopes opposite Abert Rim.
Brine shrimp are amazing creatures.
These tiny shrimp prosper in water many times saltier than
the ocean, and can tough it out in extremes. They are known to
withstand below-zero (F) temperatures, and can live with 98%
of their moisture gone, surviving droughts and even blowing in
th wind to other salty pools of water.
Brine shrimp may produce hundreds of eggs in their two month
life-span. Eggs take about two days to tach. It's no wander, with
millions of brine shrimp flaoting near the surface, that birds find
easy eating in Lake Abert.
Magnified 6 times from their actual size of 5/8 inch, brine
shrimp are small but plentiful in the alkaline waters of
A gathering place for wildlife
As the climate warmed, mineral salts that were dilute in the ancient
basin concentrated in the shallow lakes that remained. The salty
water supports millions of brine shrimp that attract an abundance of
shorebirds and waterfowl.
In contrast, fresh water from springs and streams that flow into Lake
Abert is vital for land-dwelling wildlife that feed and find homes in
the sagebrush high desert surrounding the lake.
Darting along the shore, snowy plovers and phalaropes dip the
water's edge for brine shrimp or insects. These sparrow-size
shorebirds spend most of their lives along the coast or open ocean but
come inland to nest or avoid winter gales.
Each spring and fall, southeast Oregon lakes become rest stops for
hundreds of thousands of Canada geese, ducks, and cranes, Lake
Abert, with its large supply of brine shrimp, attracts these hungry
migrants as well as oportunistic residents. April is an excellent
month for bird watching, and many birds linger through
summer and fall.