Rancho Cañada de los Osos y Pecho y Islay

Rancho Pecho y Islay was an 8,856.8-acre (35.842 km2) Mexican land grant in the Irish Hills, Montaña de Oro State Park and Diablo Canyon Power Plant in present-day San Luis Obispo County, California.

Rancho Cañada de los Osos (Valley of the Bears) was a 23,574.2-acre (95.401 km2) Mexican land grant in Los Osos Valley in present-day San Luis Obispo County, California. Rancho Cañada de Los Osos was granted by Governor Juan B. Alvarado to Victor Linares, in 1842. The Cañada de Los Osos grant extended from the Pacific Coast, along Los Osos Creek and the Los Osos Valley to almost present-day San Luis Obispo, and southward encompassed, Los Osos, Montaña de Oro State Park north of Islay Creek and the northern Irish Hills.

Montaña de Oro ("Mountain of Gold" in Spanish) is a state park in Central Coastal California, six miles southwest of Morro Bay and two miles south of Los Osos. It consists of 8,000 acres (32 km²) of cliffs, seven miles of shoreline, sandy beaches, dunes, coastal plains, streams, canyons, and hills, including the 1,347-foot (411 m) Valencia Peak. The park has many hiking, mountain biking, equestrian trails and horse campsites, as well as a primitive campground located across from Spooner's Cove, a popular beach. The Bluff Trail is an easy and popular trail along the scenic coast. Trails lead to the summits of Valencia Peak, Oats Peak, and Hazard Peak.

Islay Creek is a stream in San Luis Obispo County, California. Its mouth is at Spooners Cove on the Pacific Ocean, at . Its source is at 35°15′29″N 120°46′46″W at an elevation of 1,380 feet (420 m) in the Irish Hills.

The Diablo Canyon Power Plant is a nuclear power plant near Avila Beach in San Luis Obispo County, California. Following the permanent shutdown of the San Onofre Nuclear Generating Station in 2013, Diablo Canyon is now the only operational nuclear plant in California, as well as the state's largest single power station. It was the subject of controversy and protests during its construction, with nearly two thousand civil disobedience arrests in a two-week period in 1981. The plant has two Westinghouse-designed 4-loop pressurized-water nuclear reactors operated by Pacific Gas & Electric (PG&E). Together, the twin 1100 MWe reactors produce about 18,000 GW·h of electricity annually (8.6% of total California generation and 23% of carbon-free generation), supplying the electrical needs of more than 3 million people. The plant produces electricity for about 6 cents per kWh, less than the average cost of 10.1 cents per kWh that PG&E paid for electricity from other suppliers in 2014.Though it was built less than a mile from the Shoreline fault line, which was not known to exist at the time of construction, and is located less than three miles (4.8 km) from the Hosgri fault, a 2016 NRC probabilistic risk assessment of the plant, taking into account seismic risk, estimated the frequency of core damage at one instance per 7.6 million reactor years. The plant is located in Nuclear Regulatory Commission Region IV. In 2016, PG&E announced that it plans to close the two Diablo Canyon reactors in 2024 and 2025, stating that because California's energy regulations give renewables priority over nuclear, the plant would likely only run half-time, making it uneconomical. (Nuclear plants are used for base load in order to spread their large fixed costs over as many kWh of generation as possible.) In 2020, experts at the California Independent System Operator (CAISO) warned that when the plant closes the state will reach a "critical inflection point", which will create a significant challenge to ensure reliability of the grid without resorting to more fossil fuel usage, and could jeopardize California's greenhouse gas reduction targets. In 2021 the California Energy Commission and CAISO warned that the state may have summer blackouts in future years as a result of Diablo's closure coinciding with the shutdown of four natural gas plants of 3.7GW total capacity, and the inability to rely on imported electricity during West-wide heat waves due to reduced hydroelectric capacity (from the decades-long drought) and the closure of coal plants. A 2021 report from researchers at MIT and Stanford states that keeping Diablo Canyon running until 2035 would reduce the state's carbon emissions from electricity generation by 11% every year, save the state a cumulative $2.6 billion (rising to $21 billion if kept open until 2045), and improve the reliability of the grid. Full decommissioning of the plant is estimated to take decades and cost nearly $4 billion.

Los Osos Oaks State Natural Reserve is a California State Park in western San Luis Obispo County, in the Central Coast of California region. It preserves centuries-old coast live oaks (Quercus agrifolia) growing atop relict sand dunes. It is located in the Los Osos Valley between San Luis Obispo and Baywood Park-Los Osos, just outside the town of Los Osos. The 85-acre (34 ha) park was established in 1972.

Baywood-Los Osos (locally known as Los Osos-Baywood Park) is an unincorporated community in western San Luis Obispo County, California. The population was 14,351 in the 2000 census. It includes the communities of Los Osos, which is located near Morro Bay, Baywood Park, and the former community of Cuesta-by-the-Sea.

Point Buchon is a cape in San Luis Obispo County, California. The Point Buchon State Marine Reserve and Marine Conservation Area lies offshore from that Point. Point Buchon was named by the Coast Survey during the Civil War.Point Buchon was named after El Buchon, the Chumash chief who ruled the area when the Portola expedition passed this way in 1769. El Buchon had a large neck goiter, buchon in 18th century Spanish.

Mount Buchon, also known as the San Luis Range, is a mountain range in San Luis Obispo County, California.

Los Osos (Spanish for "the bears") is an unincorporated town in San Luis Obispo County, California, United States. Located on the Central Coast of California, Los Osos had a population estimated to be 16,533 in 2019. For statistical purposes, the United States Census Bureau has defined Los Osos as a census-designated place (CDP).

The Irish Hills are a low mountain range of the southern outer California Coast Ranges in western San Luis Obispo County, California, and the state's Central Coast region.It rises between San Luis Obispo and the Pacific Ocean, south of Los Osos Valley Road to Morro Bay.

Los Osos Back Bay is a prehistoric Chumash archaeological site in the Los Osos Valley, near the coast in San Luis Obispo County, California. These ancient Californian Native Americans had a significant settlement, now named "Los Osos Back Bay," on a stabilized sand dune. It is to the west of the Elfin Forest Natural Area, which has another midden within it. Los Osos Back Bay is also the present day name for the southernmost part of the Morro Bay estuary, known by the locals as "the back bay". It is where the native Chumash at the eponymous archaeological site gathered marine resources, as coastal tribes along this part of the California coast regularly did.