Elkhorn Slough is a tidal

slough Slough () is a town and unparished area in the unitary authority of the same name in Berkshire, England, bordering west London. It lies in the Thames Valley, west of central London and north-east of Reading, at the intersection of the M4 ...

and

estuary An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

Monterey Bay Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area and its major city at the south of the bay, San Jose. San Francisco itself is further north along the coast, by a ...

Monterey County, California Monterey County ( ), officially the County of Monterey, is a county located on the Pacific coast in the U.S. state of California. As of the 2020 census, its population was 439,035. The county's largest city and county seat is Salinas. Monte ...

. It is California's second largest estuary and the United States' first estuarine sanctuary. The community of

Moss Landing Moss Landing, formerly Moss, is an unincorporated community and census-designated place (CDP) in Monterey County, California, United States. It is located north-northeast of Monterey, at an elevation of . It is on the shore of Monterey Bay, at the ...

and the

Moss Landing Power Plant The Moss Landing Power Plant is a natural gas powered electricity generation plant located in Moss Landing, California, United States, at the midpoint of Monterey Bay. Its large stacks are landmarks, visible throughout the Monterey Bay Area. T ...

are located at the mouth of the slough on the bay. Elkhorn Slough harbors the largest tract of tidal

salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is dominated ...

in California outside the

San Francisco Bay San Francisco Bay is a large tidal estuary in the U.S. state of California, and gives its name to the San Francisco Bay Area. It is dominated by the big cities of San Francisco, San Jose, and Oakland. San Francisco Bay drains water from a ...

and provides much-needed habitat for hundreds of species of plants and animals, including more than 340 species of birds. It has been designated as a protected

Ramsar site A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention,8 ha (O) *** Permanent 8 ha (P) *** Seasonal Intermittent < 8 ha(Ts) **

History

The name of the slough derives from the native

tule elk The tule elk (''Cervus canadensis nannodes'') is a subspecies of elk found only in California, ranging from the grasslands and marshlands of the Central Valley to the grassy hills on the coast. The subspecies name derives from the tule (), a s ...

''Cervus canadensis nannodes'', now extirpated from the region. Elkhorn Slough occupies the western reaches of Elkhorn Valley, a relic river valley eroded by drainage pouring out of the Santa Clara Valley and/or Great Valley of California (before the

Golden Gate The Golden Gate is a strait on the west coast of North America that connects San Francisco Bay to the Pacific Ocean. It is defined by the headlands of the San Francisco Peninsula and the Marin Peninsula, and, since 1937, has been spanned by th ...

opened) into Monterey Bay during the early Pleistocene. In the mid-1850s A.D. Elkhorn Slough was a minor tributary to the much larger Pajaro-Salinas River system which shared a common entrance to the Pacific Ocean north of Moss Landing. In 1909 winter storms modified the course of the Salinas River to its present location south of Moss Landing, while Elkhorn Slough persisted as a tributary to the Old Salinas River channel. Construction of jetties at the Moss Landing Harbor in 1946 provided a direct link between the Pacific Ocean and Elkhorn Slough. At this time, salt marshes began to retreat from the axis of Elkhorn Slough as it evolved into its present form as a relatively stable estuarine embayment.

Watershed

Carneros Creek is the primary source of freshwater flowing into Elkhorn Slough. McClusky Slough to the north and Moro Cojo Slough to the south also provide freshwater inputs.

Conservation ownership

More than of the watershed's are protected under a

mosaic A mosaic is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and were particularly pop ...

of private and public ownership.

Foundations

The nonprofit Elkhorn Slough Foundation is the single largest land owner in the watershed, with nearly . The nonprofit

Nature Conservancy The Nature Conservancy (TNC) is a global environmental organization headquartered in Arlington, Virginia. it works via affiliates or branches in 79 countries and territories, as well as across every state in the US. Founded in 1951, The Natu ...

was the first to buy Elkhorn Slough property with the goal to protect the area's habitat and wildlife. The Nature Conservancy started with only 60 acres in 1971 and through gifts and purchases of disjointed parcels, gained over by September 2012, when it transferred to the Elkhorn Slough Foundation. The Foundation already managed conservation on these parcels. Sea-otter-morro-bay 13

Elkhorn Slough State Marine Reserve

The

Elkhorn Slough State Marine Reserve Elkhorn or Elk Horn may refer to: Places Antarctica * Elkhorn Ridge, a ridge of the Convoy Range in Victoria Land Canada * Elkhorn, Manitoba, an unincorporated community * Elkhorn Mountain, a mountain in British Columbia United States Cities a ...

(SMR) covers . The SMR protects all marine life within its boundaries. It is managed by the California Department of Fish & Wildlife (CA-DFW) in cooperation with the

National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...

. Fishing and take of all living marine resources is prohibited. It includes the waters below mean high tide within Elkhorn Slough lying: * east of longitude 121° 46.40’ W. and * south of latitude 36° 50.50’ N.

Elkhorn Slough State Marine Conservation Area

The

Elkhorn Slough State Marine Conservation Area Elkhorn or Elk Horn may refer to: Places Antarctica * Elkhorn Ridge, a ridge of the Convoy Range in Victoria Land Canada * Elkhorn, Manitoba, an unincorporated community * Elkhorn Mountain, a mountain in British Columbia United States Cities a ...

(SMCA) covers . It includes the waters below mean high tide within Elkhorn Slough: * east of the Highway 1 Bridge and * west of longitude 121° 46.40’ W. The SMR and the SMCA were both established in September 2007 by the

California Department of Fish and Wildlife The California Department of Fish and Wildlife (CDFW), formerly known as the California Department of Fish and Game (CDFG), is a state agency under the California Natural Resources Agency. The Department of Fish and Wildlife manages and protect ...

(CA−DFW). It was one of 29 marine protected areas adopted during the first phase of the

Marine Life Protection Act The Marine Life Protection Act (MLPA) was passed in 1999 and is part of the California Fish and Game Code. The MLPA requires California to reevaluate all existing marine protected areas (MPAs) and potentially design new MPAs that together form a ...

Initiative, a collaborative public process to create a statewide network of marine protected areas along the California coastline.California Department of Fish and Wildlife,
Central Coast Marine Protected Areas
" . retrieved December 23, 2008.

Elkhorn Slough National Estuarine Research Reserve

The

Elkhorn Slough National Estuarine Research Reserve The Elkhorn Slough National Estuarine Research Reserve is a nature reserve that is located at 1700 Elkhorn Road in Watsonville, California. The reserve encompasses the central shore of Monterey Bay and is approximately south of San Francisco, Cal ...

is one of 28 National Estuarine Research Reserves established nationwide as field laboratories for scientific research and estuarine education.

Local government

Additional land protected by the

Moss Landing Harbor Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and ho ...

District and the

Monterey County Parks Department Monterey (; es, Monterrey; Ohlone: ) is a city located in Monterey County on the southern edge of Monterey Bay on the U.S. state of California's Central Coast. Founded on June 3, 1770, it functioned as the capital of Alta California under bo ...

Adjacent areas

The

Moss Landing Wildlife Area Moss Landing Wildlife Area is a California State wildlife preserve on the shore of Elkhorn Slough. Description The Moss Landing Wildlife Area protects of Monterey County, California, just north of the town of Moss Landing, California. It inclu ...

protects the land north and west of the Slough. The

Moro Cojo Slough State Marine Reserve Moro Cojo Estuary State Marine Reserve (SMR) is a marine protected area established to protect the wildlife and habitats in Moro Cojo Slough. Moro Cojo Slough is located inland from Monterey Bay on the central coast of California, directly south ...

just south of Elkhorn protects a similar wetland area.

Habitat and wildlife

Elkhorn Slough, one of the largest

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environment ...

in California, provides essential habitat for over 700 species, including aquatic

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s, birds, fish,

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

alga Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mi ...

e and plants. The slough area is home to California's greatest concentration of

sea otter The sea otter (''Enhydra lutris'') is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between , making them the heaviest members of the weasel family, but among the small ...

s, as well as populations of

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...

Santa Cruz long-toed salamander and the

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensat ...

California red-legged frog The California red-legged frog (''Rana draytonii'') is a species of frog found in California (USA) and northern Baja California (Mexico). It was formerly considered a subspecies of the northern red-legged frog (''Rana aurora''). The frog is an IU ...

. The population of sea otter living in Elkhorn Slough reflect that the species is well-adapted for estuarine habitat, and may be a model for the historical sea otter populations now extinct in

. Elkhorn Slough hosts year-round residents tightly associated with estuaries, such as

pickleweed Pickleweed is a common name used for two unrelated genera of flowering plants: *'' Batis'', family Bataceae *''Salicornia ''Salicornia'' is a genus of succulent, halophytic (salt tolerant) flowering plants in the family Amaranthaceae that gro ...

eelgrass Eelgrass is a common name for several plants and may refer to: * ''Zostera'', marine eelgrass * ''Vallisneria'', freshwater eelgrass {{Short pages monitor