Big Lagoon
Kayaks at the south end of Big Lagoon
Big Lagoon Show map of California Big Lagoon Show map of the United States
Location	Humboldt County, California
Coordinates	41°11′00″N 124°07′00″W / 41.18333°N 124.11667°W / 41.18333; -124.11667
Type	Lagoon
Primary inflows	Maple Creek
Primary outflows	Pacific Ocean
Basin countries	United States
Max. length	3.8 mi (6 km)[1]
Max. width	1.4 mi (2 km)[1]
Surface area	1,470 acres (5.9 km2)[2]
Max. depth	22 feet (6.7 m)[2]
Shore length1	9 miles (14 km)[2]
Surface elevation	20 feet (6.1 m)[2]
Frozen	No
1 Shore length is not a well-defined measure.

Big Lagoon is the southernmost and largest of three similar lagoons within Humboldt Lagoons State Park, along the coast of Humboldt County, California.

It is located between Trinidad to the south and Orick at the mouth of Redwood Creek to the north.

The lagoons are shallow bays between rocky headlands where coastal wave action has formed a sandy bar separating each lagoon from the Pacific Ocean. The lagoons are resting areas for migratory waterfowl using the Pacific Flyway between Lake Earl on the Smith River estuarine wetlands 40 miles (64 km) to the north and Humboldt Bay on the Mad River estuarine wetlands 30 miles (48 km) to the south.

Big Lagoon is similar to other coastal features of northern California including Humboldt Bay to the south and Lake Earl to the north; an alluvial plain is surrounded by steep uplands. Hills adjacent to Big Lagoon have been identified as the Franciscan Assemblage along the eastern shore and Pleistocene dune sandstone to the south.^[1] Studies around Humboldt Bay indicate tectonic activity along the Cascadia subduction zone has caused local sea level changes at intervals of several centuries.^[3] The plain may support fresh water wetlands or Sitka Spruce forests following uplift events and salt marsh or inundated shellfish beds following subsidence events. At the present lagoon level, the sand bar normally separates the lagoon from the ocean during summer months. Winter precipitation may raise the water level in the lagoon a few meters above sea level. Hydrostatic pressure and storm surf may then breach the sand bar allowing the lagoon to drain into the sea and then receive tidal inflow until wave action reforms the bar.^[4]

Roosevelt elk graze the wetlands south of the lagoon and may sometimes be seen where U.S. Route 101 crosses the lagoon. Hammond Lumber Company Plant Three included 20th century company housing and a sawmill log pond built where Maple Creek enters the south end of Big Lagoon.^[5] The coastal portion of Big Lagoon was used as an aerial rocket range by the United States Navy during World War II.^[6] Canoe access to Big Lagoon is available from a park on the south shore near the community of Big Lagoon and Big Lagoon Rancheria.

The deaths of 14 dogs after going swimming have occurred in the last twenty years due to cyanobacteria in blue-green algae on the Big Lagoon, South Fork Eel River or the Van Duzen River during times of warm weather and low water flow.^[7]

The "B.E.P.O. Beast" sightings refer to a series of 1980s word-of-mouth reports of a primate-like creature roaming the outskirts of Big Lagoon. The name "B.E.P.O" is an acronym standing for "Big Elusive Primate Organism," given to the creature by locals of Humboldt Bay and by those that allegedly spotted the creature. According to those that saw the B.E.P.O. Beast, it largely resembled a sasquatch, a creature with a plethora of reports in Humboldt County and its surrounding heavily wooded areas. Reportedly covered in green-brown fur, in all reports, the creature only walked around the perimeter of Big Lagoon, namely in the wooded peninsula surrounding the coast of the lagoon. Additionally, the creature was reported to have a foul smell emitting from its fur, similar to that of rotting fish and animal feces. The smell and the hairy appearance of the B.E.P.O. Beast had led some to believe that the creature is a California species of the Skunk ape. The height of the creature, however, was allegedly significantly larger than the Floridian species, with witnesses reporting the B.E.P.O Beast to stand anywhere between eight and twelve feet tall. This wide range in heights has led some to believe that there was more than one "B.E.P.O." in Big Lagoon. Because the evidence of the B.E.P.O. Beast is anecdotal, the existence of the creature is unsubstantiated and unsupported.

One report from a local of Trinidad claims that the creature rushed towards him when spotted hiding in the trees of the wooded campground area. The creature ran towards the man, alternating between a bipedal and quadrupedal run. The man retreated in a boat off of the boat ramp, and the creature stopped upon reaching the water, splashing the shore aggressively before walking back into the trees. Despite reporting the incident to an official from the county park and later following up with the California Department of Fish and Game, no footprints, DNA, or evidence of the sighting was recovered.

The most plausible and accepted explanation of the B.E.P.O. Beast is that it was a California black bear suffering from extreme mange. Known to stand both bipedally and on all fours, the aggressive behavior and movement is reminiscent of a black bear.^[8] The coloration of the B.E.P.O Beast has been attributed to dried moss and algae from the lagoon stuck in the fur of the bear. In 1984, a vacationing zoologist by the name of Jaden Shepard was asked about the creature and proposed that in addition to mange, there may be the presence of a genetic mutation that affected the gastrointestinal regulation of the creature, which may have accelerated the mange and contributed to the creature's odor. Additionally, he proposed that if this mutation was transmissible through familial lineage, the difference in heights of the reports could be explained by a family of bears suffering from the same mutation. Because Big Lagoon is home to a large population of Roosevelt elk, it is hypothesized that these animals could be sustained by elk, local waterfowl such as pintail, wigeons, shovelers, scaup, ruddy ducks, grebes, herons, snipe, or osprey, and fish such as steelhead and coastal cutthroat.^[9]

• Freshwater Lagoon
• Stone Lagoon