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Soda Lake (San Luis Obispo County)
Encyclopedia
Soda Lake is a shallow, ephemeral, alkali
endorheic lake in the Carrizo Plain
in southeastern San Luis Obispo County, California
. The lake is located on the southwest side of the northern Carrizo Plain
, 103 km east of San Luis Obispo
. It can be reached by Soda Lake Road, which runs northwest-southeast between State Route 166
and State Route 58
. The lake is at an elevation of 580m and covers an area of about 12 km².
-Pleistocene
time when tectonic
deformation associated with the San Andreas Fault
defeated a stream
that once drained the valley. An originally fresh to brackish water lake probably persisted through much of the Pleistocene during which coastal California was wetter and cooler than now. Diminished Holocene
precipitation
and a higher evaporation
rate led to shrinkage of the ancestral lake and associated increased salinity
which set the stage for clay dune formation.
About 30% of the closed or endorheic drainage basin
is to the north of the lake and 70% is south of it. The Soda Lake complex consists of two larger basins, and at least 130 smaller pans. The large L-shaped northern basin is about 10.5 km² in area. The remaining basins, including both those that feed the northern basin and those that have no surface outlets, comprise an area of about 4.8 km². Water levels in the basins rise and fall seasonally. Rainfall on the Carrizo Plain is only about 20 cm in an average year but is higher on the surrounding mountains. Following exceptionally wet winters, typically El Niño years, the large northern and southern basins do not evaporate completely, although the water retreats toward the center of the basin leaving a salt
crust up to 20 cm thick. Most of the large and small pans are fringed by clay
dunes. It is one of the largest alkali wetland
s remaining in natural condition in California
. It supports fairy
and brine shrimp
, as well as migratory
and nesting bird
s. A boardwalk
was built along the shore to prevent damage to the saltbush habitat that borders the lake.
bounds the eastern and southern edges of the northern basin. This dune is up to 470m wide, 16.7m high, and nearly 9.5 km in length. Part of the dune is active, receiving sediment
from the mud flat exposed between the dune and the salt pan
. Most of the eastern (north-south) leg of the dune, which is lower and narrower, is currently inactive. Westward retreat of the shoreline exposed the former lake flat to colonization and stabilization by salt-resistant plants.
Alkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
endorheic lake in the Carrizo Plain
Carrizo Plain
The Carrizo Plain is a large enclosed plain, approximately 50 miles long and up to 15 miles across, in southeastern San Luis Obispo County, California, about 100 miles northwest of Los Angeles, California...
in southeastern San Luis Obispo County, California
San Luis Obispo County, California
San Luis Obispo County is a county located along the Pacific Ocean in the Central Coast of the U.S. state of California, between Los Angeles and the San Francisco Bay Area. As of the 2010 census its population was 269,637, up from 246,681 at the 2000 census...
. The lake is located on the southwest side of the northern Carrizo Plain
Carrizo Plain
The Carrizo Plain is a large enclosed plain, approximately 50 miles long and up to 15 miles across, in southeastern San Luis Obispo County, California, about 100 miles northwest of Los Angeles, California...
, 103 km east of San Luis Obispo
San Luis Obispo, California
San Luis Obispo is a city in California, located roughly midway between San Francisco and Los Angeles on the Central Coast. Founded in 1772 by Spanish Fr. Junipero Serra, San Luis Obispo is one of California’s oldest communities...
. It can be reached by Soda Lake Road, which runs northwest-southeast between State Route 166
California State Route 166
State Route 166 is a state highway in the U.S. state of California. It connects the Central Coast to the southern San Joaquin Valley....
and State Route 58
California State Route 58
State Route 58 is an east-west highway across the California Coast Ranges, the southern San Joaquin Valley, the Tehachapi Mountains, which border the southern Sierra Nevada, and the Mojave Desert. It runs between its western terminus near Santa Margarita and its eastern terminus at Barstow...
. The lake is at an elevation of 580m and covers an area of about 12 km².
Endorheic drainage basin
Internal drainage of the Carrizo Plain and the formation of Soda Lake began during PliocenePliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
-Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
time when tectonic
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...
deformation associated with the San Andreas Fault
San Andreas Fault
The San Andreas Fault is a continental strike-slip fault that runs a length of roughly through California in the United States. The fault's motion is right-lateral strike-slip...
defeated a stream
Stream
A stream is a body of water with a current, confined within a bed and stream banks. Depending on its locale or certain characteristics, a stream may be referred to as a branch, brook, beck, burn, creek, "crick", gill , kill, lick, rill, river, syke, bayou, rivulet, streamage, wash, run or...
that once drained the valley. An originally fresh to brackish water lake probably persisted through much of the Pleistocene during which coastal California was wetter and cooler than now. Diminished Holocene
Holocene
The Holocene is a geological epoch which began at the end of the Pleistocene and continues to the present. The Holocene is part of the Quaternary period. Its name comes from the Greek words and , meaning "entirely recent"...
precipitation
Precipitation (meteorology)
In meteorology, precipitation In meteorology, precipitation In meteorology, precipitation (also known as one of the classes of hydrometeors, which are atmospheric water phenomena is any product of the condensation of atmospheric water vapor that falls under gravity. The main forms of precipitation...
and a higher evaporation
Evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....
rate led to shrinkage of the ancestral lake and associated increased salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
which set the stage for clay dune formation.
About 30% of the closed or endorheic drainage basin
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...
is to the north of the lake and 70% is south of it. The Soda Lake complex consists of two larger basins, and at least 130 smaller pans. The large L-shaped northern basin is about 10.5 km² in area. The remaining basins, including both those that feed the northern basin and those that have no surface outlets, comprise an area of about 4.8 km². Water levels in the basins rise and fall seasonally. Rainfall on the Carrizo Plain is only about 20 cm in an average year but is higher on the surrounding mountains. Following exceptionally wet winters, typically El Niño years, the large northern and southern basins do not evaporate completely, although the water retreats toward the center of the basin leaving a salt
Salt
In chemistry, salts are ionic compounds that result from the neutralization reaction of an acid and a base. They are composed of cations and anions so that the product is electrically neutral...
crust up to 20 cm thick. Most of the large and small pans are fringed by clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
dunes. It is one of the largest alkali wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....
s remaining in natural condition in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. It supports fairy
Fairy shrimp
Anostraca is one of the four orders of crustaceans in the class Branchiopoda; its members are also known as fairy shrimp. They are usually long . Most species have 20 body segments, bearing 11 pairs of leaf-like phyllopodia , and the body lacks a carapace...
and brine shrimp
Brine shrimp
Artemia is a genus of aquatic crustaceans known as brine shrimp. Artemia, the only genus in the family Artemiidae, has changed little externally since the Triassic period...
, as well as migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
and nesting bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s. A boardwalk
Boardwalk
A boardwalk, in the conventional sense, is a wooden walkway for pedestrians and sometimes vehicles, often found along beaches, but they are also common as paths through wetlands, coastal dunes, and other sensitive environments....
was built along the shore to prevent damage to the saltbush habitat that borders the lake.
Dunes
The largest duneDune
In physical geography, a dune is a hill of sand built by wind. Dunes occur in different forms and sizes, formed by interaction with the wind. Most kinds of dunes are longer on the windward side where the sand is pushed up the dune and have a shorter "slip face" in the lee of the wind...
bounds the eastern and southern edges of the northern basin. This dune is up to 470m wide, 16.7m high, and nearly 9.5 km in length. Part of the dune is active, receiving sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
from the mud flat exposed between the dune and the salt pan
Salt pan (geology)
Natural salt pans are flat expanses of ground covered with salt and other minerals, usually shining white under the sun. They are found in deserts, and should not be confused with salt evaporation ponds.A salt pan is formed where water pools...
. Most of the eastern (north-south) leg of the dune, which is lower and narrower, is currently inactive. Westward retreat of the shoreline exposed the former lake flat to colonization and stabilization by salt-resistant plants.