The Salinas River flows for 175 miles (282 km) generally north-northwest through the central California Coast Ranges and enters Monterey Bay 3 miles (4.8 km) southwest of Castroville, California. The river starts in the Los Machos Hills of the Los Padres National Forest and eventually drains an area of 4,160 square miles (10,800 sq km). The final stretch of the river forms a lagoon protected by 367 acres (148.5 ha) of the Salinas River National Wildlife Refuge. The river outflow to Monterey Bay is usually blocked by sand dunes except during winter high river discharge.
The area near the mouth of the Salinas River was originally part of Rancho Bolsa Nueva y Moro Cojo. The rancho was 30,901 acres (12,505 ha) and was combined from three Mexican land grants that included Rancho Moro Cojo granted by Governor Luís Antonio Argüello in 1825, Rancho Bolsa Nueva granted by Governor Mariano Chico in 1836, and the land in between granted by Governor Juan Alvarado to Simeon Castro in 1837. With the cession of California to the United States following the Mexican-American War, the 1848 Treaty of Guadalupe Hidalgo provided that the land grants would be honored and the combined land grants were patented to Maria Antonio Pico de Castro in 1873. The rancho extended from Moss Landing inland to present-day Prunedale, and south to Castroville where at the time the land was crisscrossed by a network of sloughs and swamps. By the mid 19th century, Chinese immigrants had established a presence in Castroville and they were instrumental in clearing the slough, wetlands, and marshes to grow crops. As a result of the 1906 San Francisco earthquake, the Salinas River mouth at Monterey Bay was diverted 6 miles (9.7 km) south from an area between Moss Landing and Watsonville to a new channel just north of Marina. The Old Salinas River channel that diverts north behind the sand dunes along the ocean, is used as an overflow channel during the rainy season.
In the 18th and early 19th centuries, the river valley provided the route for travelers called El Camino Real, the principal overland route from southern to northern Alta California used by Spanish explorers and missionaries and early Mexican settlers. In 1769, when the Portola expedition first encountered the river, it was reported as a river watering a luxuriant plain filled with fish. The historic increase in agriculture and settlement in the area and the related increase in water consumption have had a significant impact. The use of river water for irrigation makes the Salinas Valley one of the most productive agricultural regions in California, however, as of the end of 2016, the river has been transformed into little more than a dry bedded run-off feature for most of its length. Read more here and here. Explore more of the Salinas River here: