In 1769, Gaspar de Portola was on his mission of exploration from San Diego to Monterey when he came upon a river he named Rio Porcinucula. With the abundant supply of water in that river, he believed it to be an ideal site for a settlement.
Word spread, and in 1781 a group of eleven families founded El Pueblo de Nuestra Senora La Reina de Los Angeles on that site. The settlers soon constructed a water system by placing a primitive brush dam across the river. The dam diverted water into the Zanja Madre (Mother Ditch) to feed several irrigation canals over fields adjacent to the river. Ownership of the water of the Los Angeles was granted “in perpetuity” by King Carlos III of Spain.
When the City of Los Angeles was incorporated in 1850, the citizens were granted all the rights that were granted to original pueblo – – including the rights to the water in the Los Angeles River.