Posted by: James Wapotich | August 5, 2014

Trail Quest: Oso Flaco Lake

To the north of Santa Barbara, along the coast near Santa Maria, is one of the largest remaining stretches of coastal dunes in California. Hidden amongst these dunes are several rare freshwater lakes.

Referred to as the Guadalupe-Nipomo Dunes Complex, this 18-mile long stretch of dunes extends from Rancho Guadalupe Dunes County Park to Pismo State Beach, and reaches inland in some places as much as three miles. And where Oso Flaco Creek meets the dunes a freshwater lake has formed.

The lake, located northwest of Santa Maria and west of Nipomo, is home to a surprising variety of plants and animals. The trail to the lake, and the boardwalk that crosses the lake and continues to the coast, provides a unique opportunity to see and experience the lake and the surrounding dunes up close. The hike to beach is about 2.5 miles round trip and the route followed is wheelchair accessible.

Oso Flaco Lake hike trail

Oso Flaco Lake

To get to the trailhead from Highway 101 in Santa Maria, take the exit for West State Route 166 which follows Main Street through Santa Maria and continues west towards Guadalupe. Continue on State Route 166 until it meets State Route 1.

From here, turn right onto State Route 1 and continue north towards Guadalupe. West Main Street continues and ends at Rancho Guadalupe Dunes County Park.

State Route 1 follows Guadalupe Street as it passes through Guadalupe, and a stop worth making in Guadalupe is a visit to the Dunes Center at 1065 Guadalupe Street. The center is a great resource for all things pertaining to the dunes. The center includes interpretive displays, as well as artifacts collected from the sets that were buried in the dunes where Cecil B. DeMille filmed his 1923 epic movie The Ten Commandments. The center is open from 10 a.m to 4 p.m., Wednesday thru Sunday. For more information about the Dunes Center go to

Continuing north past Guadalupe, stay on State Route 1. The road crosses the Santa Maria River by bridge and passes through farmland before arriving at Oso Flaco Lake Road. Turn left onto Oso Flaco Lake Road and continue west. The road ends at the parking area for the trail. Parking is $5 per day per vehicle. The park is open from sunrise to sunset. No pets are allowed.

Nearby camping is available to the north at Pismo State Beach, where campsites are available on a first come, first serve basis, and can be reserved up to seven months in advance.

Osprey Oso Flaco Lake hike trail

Osprey enjoying its dinner

Oso Flaco Lake Natural Area is in the southernmost part of Oceano Dunes State Vehicular Recreation Area (SVRA), which is managed by California Department of Parks and Recreation. And although Ocean Dunes SVRA is open to off highway vehicles, Oso Flaco Lake Natural Area is closed to OHV traffic and is separated by a buffer of open dunes.

Both the coast and the area around the lake can often be cooler, foggier, and even windier than the area further inland and so it’s best to be prepared and assess conditions at the trailhead.

From the trailhead, continue along the paved access road which leads through a surprisingly dense section of arroyo willows and other riparian plants that are supported by Oso Flaco Creek.

The road then arrives at the bridge that crosses the lake. The wooden boardwalk was built in the 1990s to redirect foot traffic away from the work being done to restore the lakeshore and dunes with native plants. From the bridge one is afforded a variety of views across the lake, as well as plenty of birding opportunities. Along the bridge are a several places with benches and interpretive signs including two that describe the birds that one might see at the lake, such as osprey, California least turn, barn swallows, and several species of ducks.

Oso Flaco Lake Gaspar de Portola Oceano Dunes SVRA Pismo Beach Guadalupe Nipomo trail hike

Upper half of Oso Flaco Lake

Oso Flaco Lake was first visited by Western Europeans when members of Don Gaspar de Portola’s overland expedition arrived at the lake in early September 1769. It’s said that men from the expedition spotted a bear along the shore of the lake, which they shot and cooked for dinner. The bear in question was somewhat lean or skinny. The next morning two members of the expedition became sick and died.

It’s said that the Chumash would sometimes hang out tainted meat in order to deal with a troublesome bear or predator. The poisoned meat, when eaten, would weaken the animal and impact its ability to compete for food, causing it to waste away. Oso Flaco is Spanish for skinny bear. Bears on occasional still visit the area.

Past the lake, the boardwalk continues through the back dunes, which are also filled with a rich variety of plant life. Here, one can find silver lupine, dune buckwheat, Blochman’s leafy daisy with its white and lavender flowers, and even dunes paintbrush with its salmon-colored flowers. The route through the dunes involves very little altitude gain or loss.

The dunes themselves owe their existence to a combination of factors. The process of dune building began roughly 18,000 years ago at the end of the last glacial period and continues today as sand is carried inland and deposited by the prevailing northwesterly winds.

Oso Flaco Lake Gaspar de Portola Oceano Dunes SVRA Pismo Beach Guadalupe Nipomo trail hike

The beach at Oso Flaco Lake Natural Area

The Santa Maria River also provides a significant amount of additional sediment to the area. Sediment from the river is deposited offshore forming sandbars during the winter. The sand is then washed up onto the beach during the summer where the wind carries it inland. Where there are plants anchoring the sand, the dunes become more stable; and where the plants have been removed or haven’t taken hold, the dunes are able to push further inland.

As the boardwalk nears the coast it arrives at an intersection. To the right, a short section of boardwalk continues towards a public restroom, and past that towards Oceano Dunes SVRA. And although the sights and sounds of OHV traffic may not be that interesting, there is a section of open dunes that is closed to OHV traffic, which acts a buffer between the two areas, that can be fun to explore.

From the intersection, the main boardwalk continues towards the beach. Another short section of boardwalk on the left leads to an overlook where, on a clear day, one can enjoys views to the south towards Mussel Rock and Point Sal, and to the north out across San Luis Bay.

The main boardwalk then ends, arriving at the beach. Beach access to the north is closed. However, one can extend the hike south along the beach and take in this stretch of pristine and rarely visited coastline.

The hike south along the beach crosses Oso Flaco Creek, and at about the 2-mile mark from the trailhead arrives at the beginning of Guadalupe-Nipomo Dunes National Wildlife Refuge.

Oso Flaco Lake Oceano Dunes hike trail Santa Maria


The refuge was established in 2000 to provide protected habitat for the endangered California least tern and the threatened western snowy plover, as well as a dozen other rare or endangered plants and animals.

The 2,553-acre refuge is open to the public. However, the only access in to the refuge is from the coast. And while one can hike along the beach year round, hiking inland is closed from March 1st through October 1st because of the nesting snowy plover.

The refuge extends along the coast for about 1.75 miles and inland about three miles. From the southern boundary of the refuge it’s another two miles to the Santa Maria River and Rancho Guadalupe Dunes County Park. A hike from the Oso Flaco Lake trailhead to the parking area at Rancho Guadalupe Dunes is about 11.5 miles roundtrip.

Regardless of how far you hike you’ll get to see some of the unique scenery found in our coastal dunes.

This article originally appeared in section A of the August 4th, 2014 edition of Santa Barbara News-Press.

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