Lobos Creek is a stream in the Presidio of San Francisco that drains urban runoff and underground springs, and flows intermittently west for 1 mile (1.6 km) from near Mountain Lake to the Pacific Ocean between Baker Beach and China Beach, about 5 miles (8 km) west of downtown San Francisco and at Sea Cliff, California. The groundwater aquifers under Mountain Lake feed Lobos Creek. The creek name is from the Spanish ‘lobo marino‘ meaning ‘sea wolf’ referring to the sea lion. Lobos Creek is the last surviving above-ground stream within the city. The San Francisco Peninsula once had numerous creeks with diverse riparian habitats, and now Hayes, Yosemite, Mission, Dolores, Eire, Precica, and Trocadero Creeks have been filled in, paved over, or placed into storm drains and sewers. Only a portion of Islais Creek and most of Lobos Creek remain but with extensive modification. In 1776, Spanish explorer Juan Bautista de Anza ended his second northward expedition at Mountain Lake. He camped for two days and located a site for the Spanish presidio. The Presidio of San Francisco, originally called El Presidio Real de San Francisco, is a former U.S. Army fort occupying the northern tip of the San Francisco Peninsula in the Golden Gate National Recreation Area. It had been a fortified location since September 17, 1776, when New Spain established the presidio to gain a foothold in Alta California and San Francisco Bay. It passed to Mexico in 1810 after the Mexican War of Independence and was turned over to the United States after the Mexican-American War in 1848. Following California statehood in 1850, American settlers started ranches, farms, and dairies where fresh water was available at lakes or creeks. In the early 1850s, John H. Baker was the owner of many acres of land in the vicinity of Lobos Creek and established a dairy called Golden Gate Ranch, or Baker’s Ranch at present-day Baker Beach. When he died in 1863, Mrs. Maria Baker secured a title to the land and subsequently mortgaged the property to John Brickell. When Baker foreclosed on the loan, Brickell secured possession of the land; however, since it was unclear where the exact property lines of Baker’s Ranch were located, a court case ruled that the federal government owned the north bank of the creek and half ownership of the water rights.

In 1857, the flourishing city needed a more dependable freshwater supply. The Bensley Company was franchised by the San Francisco City Water Works and purchased part of the Lobos Creek Ranch which included half of the water rights to Lobos Creek. The parties worked out an agreement to construct a series of flumes, tunnels, and pipes across U.S Army lands in return for providing the Presidio and Fort Point with fresh water. Getting the water from Lobos Creek to the developed areas of San Francisco became an engineering challenge since the creek lay nearly 5 miles (8 km) from the city. The company under the new name of Spring Valley Water Works dammed the mouth of Lobos Creek and constructed a wooden flume across the dunes of Baker Beach and along the bluffs. Two windmills raised the water from the flume to a storage reservoir that supplied water to the garrison at Fort Point and also to the San Francisco National Cemetery. For many years Lobos Creek furnished the city of San Francisco and the Presidio with its only public source of water. In 1862, the Spring Valley Company was granted a permit from the U.S. Army to use Mountain Lake as an additional water source. By 1877, the Spring Valley Company was supplying 2 million gallons (9,092,180 l) of Lobos Creek water per day via a wood and masonry flume 23,500 feet (7,162 m) long. When the windmills broke down, mule-drawn wagons had to supply the water to Fort Point. In 1893, slides along the ocean bluff caused Spring Valley to abandon its flume. The U.S Army maintained its own flume until 1894 when it built an almost entirely new system of wells at Mountain Lake.

Mountain Lake is in a park of 14 acres (5.7 ha) designed by William H. Hall in about 1875, who also designed Golden Gate Park. It is one of the last natural lakes in San Francisco and the only natural lake in the Golden Gate National Recreation Area. The landscape photographer Ansel Adams grew up along Lobos Creek and described the riparian habitat “at times covered, with watercress and alive with minnows, tadpoles, and a variety of larvae. Water bugs skimmed the open surfaces and dragonflies darted above the streambed. In spring flowers were rampant and fragrant. In heavy fog the creek was eerie, rippling out of nowhere and vanishing into nothingness”. During construction of the Golden Gate Bridge, excess fill was used to compress marshlands surrounding the lake and greatly reduce the size. In 1901, the city condemned the water supply from Lobos Creek as unfit for drinking purposes in its untreated state; however, the U.S. Army concluded that Lobos Creek, with a flow of 2 million gallons (9,092,180 l) per day remained the best water source. Between 1910 and 1912, the federal government constructed a new pumping plant and water treatment facility at the mouth of Lobos Creek. As of 1992, Lobos Creek provides 60% of the Presidio’s annual water requirements. In addition, water is drawn from two wells at Mountain Lake in the Lobos Creek basin and the city provides the remaining 30%. The U.S. Army imposed conditions on the approval of construction permits in the Presidio, including requiring the drainage of runoff be directed into Mountain Lake rather than onto Presidio lands. Since then, golf course pesticides and lead emissions from cars burning leaded gasoline entered the lake over many years. The lake also became a dumping ground for unwanted pets, including crawdads, large-mouth bass, goldfish, carp, bullfrogs, turtles, and an alligator, which was discovered and removed in 1996. Read more here and here. Explore more of Lobos Creek and Baker Beach here: