Denniston Creek is a 4.4 miles (7.1 km) coastal 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...

 in western San Mateo County, California

San Mateo County, California

San Mateo County is a county located in the San Francisco Bay Area of the U.S. state of California. It covers most of the San Francisco Peninsula just south of San Francisco, and north of Santa Clara County. San Francisco International Airport is located at the northern end of the county, and...

. Denniston Creek rises on the western slopes of Montara Mountain

Montara Mountain

Montara Mountain, positioned between the unincorporated community of Montara, California to the southwest and the city of Pacifica, California to the north, forms the northern spur of the Santa Cruz Mountains, a narrow mountain range running the length of the San Francisco Peninsula that separates...

 and discharges to the Pacific Ocean

Pacific Ocean

The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 at Pillar Point Harbor

Pillar Point Harbor

Pillar Point Harbor is a boat harbor created by a riprap jetty in San Mateo County, California immediately north of Half Moon Bay. The site was originally inhabited by the Ohlone people in prehistoric times, and a number of recorded shipwrecks occurred in the immediate area. The harbor facilities...

 somewhat north of El Granada Beach. The watershed of Denniston Creek is made up of relatively permeable sandy soils capable of significant recharge to its aquifers, which supply a moderate amount of potable water

Drinking water

Drinking water or potable water is water pure enough to be consumed or used with low risk of immediate or long term harm. In most developed countries, the water supplied to households, commerce and industry is all of drinking water standard, even though only a very small proportion is actually...

 to the local area.

Groundwater

In the headwaters reach high on Montara Mountain, coarse grained decomposed granite

Decomposed granite

Decomposed granite, also known as DG, is granitic rock that has weathered to the point that it readily fractures into smaller pieces or chunks of weak rock. Further weathering produces rock that easily crumbles into mixtures of gravel, sand, and silt-sized particles with some clay...

 overlies heavily fractured granitic

Granite

Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

 based bedrock

Bedrock

In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...

 aquifer

Aquifer

An aquifer is a wet underground layer of water-bearing permeable rock or unconsolidated materials from which groundwater can be usefully extracted using a water well. The study of water flow in aquifers and the characterization of aquifers is called hydrogeology...

s. This upper pocket groundwater

Groundwater

Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...

 complex feeds down-basin alluvial fan deposits on the coastal plain

Coastal plain

A coastal plain is an area of flat, low-lying land adjacent to a seacoast and separated from the interior by other features. One of the world's longest coastal plains is located in eastern South America. The southwestern coastal plain of North America is notable for its species diversity...

. These alluvial fans exhibit some characteristics of a confined aquifer, but also respond to pressure and recharge from 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...

.

Mouth

At the mouth of Denniston Creek, the stream cuts through a gently sloping marine terrace plain of alluvium. In a 1980s biological survey, sightings of the endangered San Francisco garter snake

San Francisco garter snake

The San Francisco Garter Snake is a slender multi-colored colubrid snake. Designated as an endangered species since the year 1967, it is endemic to California and resides only in San Mateo County, California, and the extreme northern part of coastal Santa Cruz County, California...

 were made. Denniston Creek is within the domain of the San Mateo County Local Coastal Plan

See also

• Arroyo de en Medio
  Arroyo de en Medio
  Arroyo de en Medio is a coastal stream in western San Mateo County, California. Arroyo de en Medio rises on the western slopes of Montara Mountain and discharges to the Pacific Ocean at Half Moon Bay at the location of the unincorporated community of Miramar at Miramar Beach...
  
  
• List of watercourses in the San Francisco Bay Area
• Rare species
  Rare species
  A rare species is a group of organisms that are very uncommon or scarce. This designation may be applied to either a plant or animal taxon, and may be distinct from the term "endangered" or "threatened species" but not "extinct"....
  
  
• Riparian zone
  Riparian zone
  A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the fifteen terrestrial biomes of the earth. Plant habitats and communities along the river margins and banks are called riparian vegetation, characterized by...