The river flowing through Petaluma. View is to the southeast.
|Name origin: Coast Miwok|
|Region||Sonoma and Marin counties|
|- left||Lichau Creek, Lynch Creek, Washington Creek, Adobe Creek|
|- right||San Antonio Creek|
|- location||1.5 mi (2 km) southwest of Cotati, California|
|- elevation||332 ft (101 m)|
|Mouth||San Pablo Bay|
|- location||5 mi (8 km) east of Novato, California|
|- elevation||0 ft (0 m)|
|Length||18 mi (29 km) |
|Discharge||for Petaluma (USGS gage station 11459000) |
|- average||17 cu ft/s (0 m3/s)|
|- max||9,620 cu ft/s (272 m3/s)|
|- min||0 cu ft/s (0 m3/s)|
The Petaluma River is a river in the California counties of Sonoma and Marin that becomes a tidal slough near its mouth. It springs from farmlands southwest of Cotati and flows generally southward through Petaluma's old town and 10 mi (16 km) of tidal marshes to end in northwest San Pablo Bay.
The word Petaluma, may derive from the Miwok words pe’ta, flat, and luma, back. The Miwok people lived in Sonoma County for more than 2500 years. Petaluma was the name of a village on a low hill east of Petaluma creek and north east of the present day town of Petaluma. The first recorded exploration of the Petaluma River was by Captain Fernando Quiros in October, 1776. While other members of his Spanish expedition collected adobe and timber for the new Presidio of San Francisco and for the Mission San Francisco de Asís (Mission Dolores), Quiros and his sailors tried unsuccessfully to sail from San Pablo Bay to Bodega Bay.
Petaluma River Watershed 
Located in southern Sonoma County, California, and a portion of northeastern Marin, the Petaluma River Watershed drains 146 square miles (380 km2). The watershed is approximately 19 miles (31 km) long and 13 miles (21 km) wide with the City of Petaluma near its center. At 2,295 feet (700 m), Sonoma Mountain is the highest point in the watershed, and its western slopes drain to the Petaluma River by way of tributaries such as Lichau Creek, Lynch Creek, Washington Creek, and Adobe Creek. The lower 12 miles (19 km) of the Petaluma River flow through the Petaluma Marsh, the largest remaining salt marsh in San Pablo Bay. The marsh covers 5,000 acres (20 km2) and is surrounded by approximately 7,000 acres (28 km2) of reclaimed wetlands. In the marshes west of Lakeville, the river is joined by San Antonio Creek, at which point it becomes the boundary between Marin County and Sonoma County. The river flows under State Route 37 at Green Point and enters northwest San Pablo Bay just north of Petaluma Point.
While the river's source lies over 300 ft (100 m) above sea level, it descends to 50 ft (15 m) within about 0.4 mi (600 m). The river is fully tidal 11 mi (18 km) from its mouth, indicating its slight gradient through the marshes below Petaluma. The United States Army Corps of Engineers dredges this section to keep it navigable by gravel barges and pleasure craft.
The Petaluma River Watershed hosts several federally endangered animals including the Salt marsh harvest mouse (Reithrodontomys raviventris), Peregrine Falcon (Falco peregrinus anatum), California Clapper Rail (Rallus longirostris obsoletus), Winter-Run Chinook salmon (Oncorhynchus tshawytscha). Endangered flora include Soft Bird’s-Beak (Cordylanthus mollis ssp. mollis), Baker’s Stickyseed (Blennosperma bakeri), Burke’s Goldfields (Lasthenia burkei), Showy Indian clover (Trifolium amoenum), Sebastopol meadowfoam (Limnanthes vinculans).
The Steelhead trout (Oncorhyncus mykiss) that spawn and rear in the Petaluma River watershed are wild, not hatchery, stock. Chinook are seen in the main stem of the Petaluma River and The United Anglers of Casa Grande High School have seen chinook at the turning basin, near the Lynch Creek confluence. The high school students constructed a salmonid hatchery in 1993 and in 2002 74 Chinook salmon returned to spawn in the Adobe Creek tributary.
Habitat and pollution 
The marshes provide an important wildlife habitat and fish hatchery. However, since the onset of intensive European immigration in the mid-1850s, the water quality has diminished, partly due to overgrazing and other agricultural uses. Pollutants present in the river include nitrates, phosphates, petroleum hydrocarbons, pesticides and sediment. Urban runoff, particularly from the City of Petaluma, adds heavy metals and hydrocarbons to the river. Starting about 1990, material steps were taken to mitigate the pollution. However, continuing population growth makes it difficult to attain the State of California's water quality goals.
Because the Petaluma River is relatively well-protected, most of the pollution comes from nearby storm drains. It is up to the people of Petaluma to keep the river clean.
When walking along the River, one can see, just by looking, a lot of pollution and garbage, but despite that, the river is actually clean enough to swim in because it is not polluted with toxins. Because of the tides and its shallow nature, it has a lot of dirt and soot that make it appear dirty when it is, in reality, not that bad.
The Petaluma wetlands that is connected to the river is one of the last remaining protected wetlands in the state of California and on the west coast. It acts as a water filtering system that also keeps the river very clean. Because it is protected so well, it keeps the ecosystem thriving so that everything runs as it should.
The biggest threat to the Petaluma River right now is from the possibility of a concrete plant being built near it. This plant is called Dutra and the loud noises it will create will scare away the birds and throw off the entire ecosystem. Despite common beliefs, noise pollution is actually extremely harmful. 
Bridges span the Petaluma River at the following locations: California State Route 37, U.S. 101, Corona Road, Petaluma Boulevard North, and four places in Petaluma (D Street, Payran Street, Washington Street, and Lakeville Street). The longest of these, the 4-lane Route 37 bridge, is 2,183 ft (665 m) long and was built in 1958. The oldest bridge, built in 1925, is a 114 ft (35 m) concrete triple span carrying two lanes of Petaluma Boulevard North.
See also 
- Endangered species
- List of rivers in California
- List of watercourses in the San Francisco Bay Area
- U.S. Geological Survey Geographic Names Information System: Petaluma River
- "Flow: Monthly Average Petaluma River at Petaluma 1949-1963". Retrieved 2007-12-10.
- Adair Heig (1982). History of Petaluma, A California River Town. San Francisco, California: Scottwall Associates.
- The Southern Sonoma County Resource Conservation District (July, 1999). Petaluma Watershed Enhancement Plan (Report). The State Water Resources Control Board. http://sscrcd.org/publications.php#pwep. Retrieved June 24, 2010.
- Prunuske Chatham, Inc. (February, 1999). Fisheries Enhancement Opportunities in the Petaluma River Watershed (Report). Southern Sonoma County Resource Conservation District. http://sscrcd.org/pdf/App.I-FisheriesEnh_web.pdf. Retrieved June 24, 2010.
- Malcolm MacConnell (1999). "Miracle at Adobe Creek". Reader's Digest. Retrieved June 24, 2010.
- "Project Highlights". United Anglers of Casa Grande High School. 2001. Retrieved June 24, 2010.
- Petaluma River Water Quality Profile
- Kay Ransom, C. Michael Hogan, Ballard George et al., Environmental Impact Report for the Petaluma General Plan, prepared by Earth Metrics Inc. for the city of Petaluma (1986)
- "National Bridge Inventory Database".
- The Southern Sonoma County Resource Conservation District
- Petaluma Wetlands Alliance
- United Anglers of Casa Grande High School
- real-time measurements
- LIVE Blue Heron Nesting Camera Petaluma River, Petaluma, CA
- PRBO Conservation Science (based in Petaluma)