Stemple Creek is a 16 mi (26 km) long, westward-flowing 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 the 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...

 counties of Sonoma

Sonoma County, California

Sonoma County, located on the northern coast of the U.S. state of California, is the largest and northernmost of the nine San Francisco Bay Area counties. Its population at the 2010 census was 483,878. Its largest city and county seat is Santa Rosa....

 and Marin

Marin County, California

Marin County is a county located in the North San Francisco Bay Area of the U.S. state of California, across the Golden Gate Bridge from San Francisco. As of 2010, the population was 252,409. The county seat is San Rafael and the largest employer is the county government. Marin County is well...

, which feeds into the Estero de San Antonio

Estero de San Antonio

Estero de San Antonio is a stream in the northern California counties of Marin and Sonoma which empties into Bodega Bay.-Course:The Estero springs just north of the Marin-Sonoma county line and runs south along Gericke Road into Marin County...

. Its waters ultimately reach Bodega Bay

Bodega Bay

Bodega Bay is a shallow, rocky inlet of the Pacific Ocean on the coast of northern California in the United States. It is approximately across and is located approximately northwest of San Francisco and west of Santa Rosa...

, part of the Gulf of the Farallones National Marine Sanctuary

Gulf of the Farallones National Marine Sanctuary

The Gulf of the Farallones National Marine Sanctuary is one of 13 marine sanctuaries in the U.S., found outside San Francisco's Golden Gate surrounding the Gulf of the Farallones-History:...

 on 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...

.

Course

Stemple Creek springs from low-lying coastal hills 2 mi (3 km) southwest of Cotati

Cotati, California

Cotati is an incorporated city in Sonoma County, California, U.S.A., located about north of San Francisco in the 101 corridor between Rohnert Park and Petaluma....

. It crosses under Stony Point Road and runs about 1 mi (1.6 km) southeast before turning westward. It passes south of Two Rock, California

Two Rock, California

Two Rock is an unincorporated community in Sonoma County, California, United States. It is located on Stemple Creek in a rural area west of Petaluma...

, then crosses into Marin County just west of Training Center Petaluma

Training Center Petaluma

Training Center Petaluma is a Coast Guard training facility in the northern California counties of Sonoma and Marin. Approximately 4,000 students train there each year. It was formerly the U.S. Army Two Rock Ranch Station....

. The creek follows a sinous course across northern West Marin

West Marin

West Marin is the largest rural region of Marin County, California.The West Marin Chamber of Commerce includes seven unincorporated communities in its definition of West Marin: Point Reyes Station, Olema, Stinson Beach, Bolinas, Tomales, Dillon Beach, and Inverness...

, with bridges at Alexander Road, Twin Bridge Road, and State Route 1

California State Route 1

State Route 1 , more often called Highway 1, is a state highway that runs along much of the Pacific coast of the U.S. state of California. It is famous for running along some of the most beautiful coastlines in the world, leading to its designation as an All-American Road.Highway 1 does not run...

, to a confluence with the Estero de San Antonio

Estero de San Antonio

Estero de San Antonio is a stream in the northern California counties of Marin and Sonoma which empties into Bodega Bay.-Course:The Estero springs just north of the Marin-Sonoma county line and runs south along Gericke Road into Marin County...

 just west of State Route 1.

Environmental factors

California's 1994 water quality report designated Stemple Creek as an "impaired" streamway as defined in section 303(d) of the Federal Water Resource Statutes, due to runoff from pasture land and feedlots. Pollutants found at hazardous level in the creek have included copper

Copper

Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

, ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

, and zinc

Zinc

Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...

.

Bridges

Bridge

Bridge

A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...

s cross Stemple Creek at Route One, Pepper Road, Twn Bridge Road, Alexander Road, Tomales Road, Valley Ford Road, Mecham Road, and Pepper Road. The newest and longest of these, built in 1982, is the 210 ft (64 m) long concrete slab

Concrete slab

A concrete slab is a common structural element of modern buildings. Horizontal slabs of steel reinforced concrete, typically between 10 and 50 centimeters thick, are most often used to construct floors and ceilings, while thinner slabs are also used for exterior paving.In many domestic and...

structure at milepost 47.41 on State Route 1. The oldest, built in 1915, is the 39 ft (11.9 m) concrete tee beam bridge carrying Valley Ford Road, located 7.5 mi (12.1 km) from State Route 1.