San Elijo Lagoon is 915 acres (370 ha) of tidal wetlands formed by Escondido Creek at Cardiff-by-the-Sea, a beach community in Encinitas, about 89 miles (144 km) southeast of Los Angeles and 21 miles (34 km) north-northwest of San Diego, California. The community is named after Cardiff, Wales. The creek drains a watershed of 54,000 acres (22,000 ha) and flows southwest for 26 miles (42 km) to the lagoon. The Portolá Expedition named the area including the lagoon “San Alejo” in 1769, in honor of Saint Alexius. The lagoon is constrained to the north and south by rocks of the Delmar Formation exposed in seashore cliffs and overlaid by Torrey Sandstone. The formation consists of dark-green claystone and mudstone, and greenish-grey muddy sandstone that developed during the Eocene period, when sediments accumulated in a large ancient lagoon. The present lagoon is one of the largest remaining coastal wetlands in southern California and supports unique plant communities including coastal strand, salt marsh, riparian scrub, coastal sage scrub, freshwater marsh, and mixed chaparral. Water from Escondido Creek is used for agricultural irrigation, municipal and domestic supply, recreation and wildlife habitat. These requirements result in low river discharge, allowing winter storms to build a sandbar that blocks the lagoon mouth at Cardiff State Beach. The sand is mechanically dredged each spring to reopen the lagoon and restore tidal circulation.

The lagoon and surrounding lands are the traditional territory of the Ipai tribe, part of the Kumeyaay people. The Kumeyaay also consist of the Tipai tribe, which lived to the south, and the Kamia, which lived to the east. The Spanish referred to them all as the Diegueño. In 1769 the Spanish started colonizing Alta California with the construction of 21 missions along the coast. In 1821, following the Mexican war of independence, the mission lands were secularized and much of the land was granted to prominent Mexican soldiers. In 1842 Rancho Las Encinitas, a land grant of 4,434 acres (1,794 ha), was given to Andrés Ybarra by Governor Juan Alvarado. The grant was named “Los Encinitos”, which means “little oaks”, but was later misspelled as “Las Encinitas”. The grant extended north for five miles (8 km) from San Elijo Lagoon to Batiquitos Lagoon. In 1860 Ybarra sold the property, and thereafter it was exchanged by several owners until 1875, when the pioneer MacKinnon family developed a farm and grew barley and corn, plus an orchard. In 1909 J. Frank Cullen purchased and subdivided the land for residential lots. Frank Cullen’s wife was a native of Cardiff, Wales, and persuaded him to name the community “Cardiff-by-the-Sea”.

When the lands surrounding San Elijo Lagoon and Escondido Creek were developed, the area began to undergo vegetational modifications, mainly because of farming and cattle-grazing. Between 1934 and 1973 sewage from various sources was discharged directly into the lagoon, and between 1937 and 1971 numerous dikes and levees were installed to construct duck ponds for hunting. In 1983 the lagoon was designated as the San Elijo Lagoon Ecological Reserve by the California Fish and Game Commission to preserve and maintain the coastal wetland habitat and the associated flora and fauna. In 2010 Swami’s State Marine Conservation Area was established as a marine protected area of 8,096 acres (3,276 ha) that extends 3.5 miles (5.6 km) offshore between Cardiff State Beach at San Elijo Lagoon to the south and Moonlight State Beach to the north. The conservation area includes a concentration of rocky reef, kelp forest and surf grass habitat, and limits the removal of marine wildlife from within its borders. The area is named for the popular surf location at Swami’s, famous for smooth and consistent wave shape. Read more here and here. Explore more of San Elijo Lagoon and Cardiff-by-the-Sea here: