|Rio de San Antonio, Rio del Pajaro|
Aerial view of the Pajaro River at Watsonville, California. The river empties into the Pacific Ocean about 2.5 miles (4 km) west of this photograph. View is to the east.
|Region||Santa Cruz, Monterey, Santa Clara,
and San Benito counties
|- left||Pacheco Creek, San Benito River|
|- right||Llagas Creek, Uvas Creek/Carnaderas Creek, Salsipuedes Creek|
|Source||San Felipe Lake|
|- location||7 mi (11 km) east of Gilroy|
|- elevation||146 ft (45 m)|
|- location||5 mi (8 km) southwest of Watsonville|
|- elevation||0 ft (0 m)|
|- coordinates||Coordinates: |
|Length||30 mi (48 km)|
|Basin||1,300 sq mi (3,367 km2)|
|- average||163 cu ft/s (5 m3/s)|
|- max||25,100 cu ft/s (711 m3/s)|
|- min||0 cu ft/s (0 m3/s)|
The Pajaro River (pájaro is bird in Spanish), in Northern California, forms part of the border between San Benito County and Santa Clara County, the entire border between San Benito County and Santa Cruz County, and the entire border between Santa Cruz County and Monterey County. Flowing roughly east to west, the river empties into Monterey Bay, west of Watsonville, California.
The first European land exploration of Alta California, the Spanish Portolà expedition, camped near the river for two nights, in the vicinity of today's community of Pajaro, on October 8–9, 1769. The party continued north the next day toward Santa Cruz. Expedition soldiers called it "Pajaro" (meaning "bird" in Spanish) because the natives they saw there had a large stuffed bird. Franciscan missionary Juan Crespi, traveling with the expedition, noted in his diary that, "to some of our party it looked like a royal eagle" (possibly an osprey).
The Pajaro River has had many names. Early Spanish maps had the name Rio de San Antonio and Rio del Pajaro. Alternate names included Pigeon River, Rio de La Senora La Santa Ana, Rio del Paxaro, Rio de Santa Ana, San Antonio River and Sanjon del Tequesquite.
The watershed is approximately 1,300 square miles (3,400 km2) and covers portions of Santa Cruz, Santa Clara, San Benito, and Monterey Counties. The Pajaro River mainstem begins just west of San Felipe Lake, also called Upper Soap Lake, which is a permanent natural lake formed by the confluence of Pacheco Creek, Tequisquita Slough and Ortega Creek. Pacheco Creek's headwaters are in the Diablo Range at about 400 feet (120 m) elevation. The Pajaro River mainstem flows west for 30 miles (50 km), passing the city of Watsonville and emptying into Monterey Bay. Lower Soap Lake, also called Soap Lake, is an intermittent body of water a few miles downstream of the upper lake. This type of water body forms when the channel below is unable to keep up with the flow coming from upstream.
San Felipe Lake lies just south of the Santa Clara County line in San Benito County, just south of Highway 152 east of Gilroy at the foot of the Diablo Range. The lake is a sag pond dammed by the fault scarp of the Calaveras Fault, which forms a natural dike along the western shoreline. It is perennial in all but the driest years, e.g. 1977. San Felipe Lake used to be 50% larger until the man-made North and South Outflow canals, which drain to the Miller Canal, were cut through the western rim in 1874.
The Pajaro River's largest tributary is the San Benito River which is much longer than the Pajaro, flowing northwest from its source at an elevation of 4,760 feet on San Benito Mountain on its course between the Diablo Range and the Gabilan Range, traveling for about 65 miles (105 km) before its confluence with the Pajaro River, about 15 miles (24 km) upstream from the ocean. The lowest tributary of the Pajaro River is Salsipuedes Creek which drains the Corralitos Creek and Salsipuedes Creek sub-basins.
A residential development, agricultural fields, and Zmudowski State Beach border the Pajaro River mouth and the connecting Watsonville Slough. The river mouth is often open to tidal action for extended periods, especially during the winter months. Should the mouth fill with sediment, it must be physically reopened to prevent nearby agricultural fields from flooding.
In 2006, the Pajaro River was designated as America's most endangered river by the American Rivers organization, due to levees constructed by the Army Corps of Engineers along its lower 22 miles (35 km) and severe runoff into the river from agricultural fields.
San Felipe Lake, which is the central feature of the “Bolsa de San Felipe”, is designated as a “California Important Bird Area” by the National Audubon Society. The Bolsa is a crossroads for birds migrating between San Francisco Bay to the north, Monterey Bay to the west and the Central Valley to the east. The Bolsa is also identified by the National Audubon Society as a “bird vagrant trap”, a site where bird species far outside of their normal range appear.
The Pajaro River serves as a migration pathway for adult Steelhead trout (Oncorhynchus mykiss) migrating to spawning and nursery habitat in the upper watershed creeks (Uvas, Llagas and Corralitos), although the Pajaro River mainstem provides poor spawning and rearing habitat due to low summer flows and high sedimentation loads. Coho salmon (Oncorhyncus kisutch) have not been present in the river since at least the late 1960s.
Historically it is interesting as one of two Northern California coastal rivers mentioned in 1829 by Russian explorer K. T. Khlebnikov as hosting sturgeon, presumably White sturgeon (Acipenser transmontanus), along with the Russian River.
Also noteworthy is perhaps the southernmost record of North American river otter (Lontra canadensis) in a California coastal watershed. In 1969 river otter were recorded eating freshwater mussels (California floater (Anodonta californiensis)) on the Santa Ana Creek tributary of Tequisquita Slough, 2 miles east of Hollister.
- U.S. Geological Survey Geographic Names Information System: Pajaro River
- Bolton, Herbert E. (1927). Fray Juan Crespi: Missionary Explorer on the Pacific Coast, 1769-1774. HathiTrust Digital Library. pp. 208–209. Retrieved April 2014.
- David L. Durham (2000). Durham's place names of California's Central Coast: includes Santa Barbara, San Luis Obispo, San Benito, Monterey & Santa Cruz counties. Quill Driver Books. p. 143. ISBN 978-1-884995-29-3. Retrieved 2010-07-05.
- "Pajaro River Watershed Integrated Regional Water Management Plan Work Plan" (PDF). May 2005. Retrieved 2010-07-05.
- "San Felipe Lake". Geographic Names Information System. United States Geological Survey.
- Casagrande, Julie Renee (2010). Aquatic Ecology of San Felipe Lake, San Benito County, California. Master's Theses. Paper 3803. (Thesis). San Jose State University. Retrieved 2012-12-02.
- "The Pajaro River" (PDF). The Trust for Public Land. Retrieved 2010-07-05.
- "America's Most Endangered Rivers of 2006" (PDF). American Rivers. 2006. Retrieved 2010-07-05.
- K. T. Khlebnikov (1940). "Memoirs of California". Pacific Historical Review 9: 307–336. doi:10.2307/3632910. JSTOR 3632910.
- D. Victor Morejohn (1969). "Evidence of River Otter Feeding on Freshwater Mussels and Range Extension". California Fish and Game 55 (2): 83–85.
- Public Works, Watsonville. "River Access". City Website. Retrieved 8 April 2011.
- J. Chown. "City awarded grant to improve river access". Register Pajaronian. Retrieved 8 April 2011.