Petaluma River

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Coordinates: 38°6′38″N 122°29′15″W / 38.11056°N 122.48750°W / 38.11056; -122.48750
Petaluma River
river
Petaluma California aerial view.jpg
The river flowing through Petaluma. View is to the southeast.
Name origin: Coast Miwok
Country United States
State California
Region Sonoma and Marin counties
Tributaries
 - left Lichau Creek, Lynch Creek, Washington Creek, Adobe Creek
 - right San Antonio Creek
City Petaluma, California
Source
 - location 1.5 mi (2 km) southwest of Cotati, California
 - elevation 332 ft (101 m)
 - coordinates 38°18′18″N 122°43′3″W / 38.30500°N 122.71750°W / 38.30500; -122.71750 [1]
Mouth San Pablo Bay
 - location 5 mi (8 km) east of Novato, California
 - elevation 0 ft (0 m)
 - coordinates 38°6′38″N 122°29′15″W / 38.11056°N 122.48750°W / 38.11056; -122.48750 [1]
Length 18 mi (29 km) [1]
Discharge for Petaluma (USGS gage station 11459000) [2]
 - 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 mouth of the Petaluma River on San Pablo Bay. View is to the northeast.

The Petaluma River is a river in the California counties of Sonoma and Marin[1] that becomes a tidal slough near its mouth. The headwaters are in the area southwest of Cotati. The flow is generally southward through Petaluma's old town, where the waterway becomes navigable, and then flows another 10 mi (16 km) through tidal marshes before emptying into the northwest corner of San Pablo Bay.

History[edit]

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.[3]

Petaluma River Watershed[edit]

Located in southern Sonoma County, California, and a portion of northeastern Marin, the Petaluma River Watershed drains 146 square miles (380 km2).[4] 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.[4] 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.

Ecology[edit]

Petaluma River Watershed 2007 Steelhead Trout Biosurvey

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). 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).[4]

Steelhead (Oncorhyncus mykiss) that spawn and rear in the Petaluma River watershed are wild, not hatchery, stock.[5] Chinook salmon (Oncorhynchus tshawytscha) 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[6] and in 2002 74 Chinook salmon returned to spawn in the Adobe Creek tributary.[7]

Habitat and pollution[edit]

The marshes provide an important wildlife habitat and fish hatchery. However, since the onset of intensive 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.[8] Urban runoff, particularly from the City of Petaluma, adds heavy metals and hydrocarbons to the river.[9] Starting about 1990, material steps were taken to mitigate the pollution.

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.

Because most of the length of the waterway is tidal and urban/suburban, there is a significant collection of tidally deposited debris along the banks. Despite the poor aesthetics including turbidity, the water quality is not particularly poor.[10]

It has been alleged that the greatest threat to the Petaluma River is the planned Dutra asphalt plant. The reported concerns involve the "loud noises it will create" that will scare away the birds and "throw off the entire ecosystem".[11]

Bridges[edit]

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.[12]

The Petaluma Blvd South Interchange project will construct a new interchange at Petaluma Blvd South, frontage roads and replace the Petaluma River bridge. The existing Petaluma River bridge is an 866 feet long, twin reinforced concrete box girder (with pre-cast I girder span over the river) bridge that was built in 1955. The existing bridge has two lanes of traffic in each direction and no shoulders The new bridge will be 907 feet long with three lanes of traffic in each direction and standard shoulders. This will be one of the longest precast, post-tensioned spliced concrete girder bridges in the U.S. Constructing the new bridge over the Petaluma River, which is a navigation channel, will be very challenging. The bridge will be constructed in three stages and require erection of 99 girders up to 130 feet in length and weighing up to 60 tons each.

The project will also replace the existing South Petaluma Blvd On/Off Ramps constructed underneath Highway 101 in the mid 1950's with a new "diamond" interchange with a decorative gateway structure (overcrossing).

Construction is anticipated to be complete by the end of in 2016.[13]

See also[edit]

References[edit]

  1. ^ a b c d U.S. Geological Survey Geographic Names Information System: Petaluma River
  2. ^ "Flow: Monthly Average Petaluma River at Petaluma 1949-1963". Retrieved 2007-12-10. 
  3. ^ Adair Heig (1982). History of Petaluma, A California River Town. San Francisco, California: Scottwall Associates. 
  4. ^ a b c 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.
  5. ^ 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.
  6. ^ Malcolm MacConnell (1999). "Miracle at Adobe Creek". Reader's Digest. Retrieved June 24, 2010. 
  7. ^ "Project Highlights". United Anglers of Casa Grande High School. 2001. Retrieved June 24, 2010. 
  8. ^ Petaluma River Water Quality Profile
  9. ^ 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)
  10. ^ http://cityofpetaluma.net/wrcd/pollution-prevention.html
  11. ^ http://nopetalumaasphaltplant.com/
  12. ^ "National Bridge Inventory Database". 
  13. ^ "Caltrans Project Page". 

External links[edit]