Posted by: James Wapotich | August 26, 2018

Trail Quest: San Ysidro Canyon

The Thomas Fire started on December 4, 2017, and burned more than 280,000 acres, roughly 440 square miles, before it was contained. And while we all breathed a collective sigh of relief when the fire was stopped behind Montecito, it proved to be just the opening salvo in a two-part disaster.

On January 9, the first winter storm hit, three days before the fire was officially contained. The unusually intense rain triggered a debris flow that devastated Montecito, claiming the lives of 23 people and damaging or destroying more than 450 structures.

Driving to the trailhead for San Ysidro Trail, the damage wrought by the debris flow is inescapable. Where East Valley Road crosses San Ysidro Creek, houses can be seen that have been partially destroyed, while others have been completely removed. Still visible on the buildings and trees is dried mud showing the height of the debris flow; and covering the ground is a layer of mud showing how far out the debris flow spread.

The trails within the burn area were also damaged. While most of the trails have been reopened, many are in need of repair and not necessarily hikeable. Substandard trail conditions and unstable ground require caution in hiking and in some cases are not safe to traverse. For example, there is a washed out section along upper San Ysidro Trail that is not safe to cross.

Cold Springs Canyon remains closed, although the uppermost portion of Cold Spring Trail can be accessed from East Camino Cielo Road.

The trailhead for San Ysidro Trail is reached from Santa Barbara by taking Highway 101 south. Exit at San Ysidro Road and continue north to East Valley Road. Turn right onto East Valley Road and continue to Park Lane. Turn left onto Park Land and follow it to East Mountain Drive, which ends at the trailhead.

The trail follows an easement through private property and where it joins a private access road, the house that was immediately on the left is now completely gone. The parcel of land it stood on also appears partially swept away and is now fenced off. Please respect private property.

The easement continues just west of the access road and rejoins the road past a gate, near the beginning of Old Pueblo Trail, which is also open. Here, the trail follows an unpaved Edison access road up the canyon. All of the Edison access roads in the burn area have been cleared and are in excellent condition.

Continuing up the canyon, the damage from the fire and debris flow is evident. The understory and chaparral have been burned away. The creek channel is much deeper and the floodplain has been largely cleared of plants and trees.

Nonetheless plants are growing back and much of the canopy is still intact. Along the road, large-flowered phacelia, canyon sunflower, and nightshade are in bloom.

The road passes the beginning of McMenemy Trail, marked now with just cairns, as the sign has been washed away. Further up the canyon, the Edison access road branches. The road to the right leads towards Buena Vista Canyon, while the main road continues up the canyon.

The access road then arrives at the beginning of the single-track trail, before crossing the creek and continuing east towards Hot Springs Canyon.

Hiking up the single-track trail, I can see where the debris flow spilled out of the creek, flowing across parts of the trail, and depositing trees and brush, some of which have been cut out and cleared by volunteers.

The canyon then starts to narrow and it’s easy to imagine the debris flow being channeled through here before starting to spread out near the mouth of the canyon. Much of Montecito is built on historic alluvial fans created by similar debris flows thousands of years ago.

Scanning the creek, many of the scenic cascades along the trail are either gone or have become unrecognizable. The familiar pool where the water flowed between two large outcrops of sandstone is gone. Over time, I imagine, new cascades will take shape and the canyon will once again become more picturesque.

The trail then climbs above the creek, returning back down just before it crosses San Ysidro Creek. Here, the trail follows a side creek towards San Ysidro Falls, before making its way to the top of the mountains.

The day is already hotter than I’d like. Recalling from previous hikes that the balance of the trail is uphill and unshaded, I decide to follow San Ysidro Creek and explore off-trail.

I hike upstream to where two side creeks join the main creek. Normally, to travel further would require bushwhacking and weaving through downed trees, but the mixed blessing of the debris flow is that it has cleared the way up each of the creeks.

In one canyon, I find fresh bear tracks and a large patch of Humboldt lilies in bloom that are being visited by swallowtail butterflies. In another canyon, I find a pair of garter snakes and stumble across a Humboldt lily with an impressive 28 flowers.

Before leaving, I pay a quick visit to the falls. The creek below them has also been carved out, but the falls appear largely as before, with the same trickle of water one would expect this time of year.

On my second hike, getting an earlier start, I quickly make my way to the falls. From here, the trail starts its climb up the mountain, making its way up a hillside of loose Cozy Dell shale. The trail is washed out, but passable with care.

As I continue, the task becomes more grueling; loose shale covers large parts of the trail requiring extra care to traverse. Even with trekking poles, the effort is like walking uphill in dry sand.

Further up, trail conditions start to improve as the trail joins the ridge separating the side canyon with San Ysidro Falls and the main canyon of San Ysidro Creek. Here, the devastation wrought by the fire can be seen over a wide area. It’s also easy to see where much of the material from the debris flow originated over the years.

Even with their chaparral covering, these mountains represent an almost endless supply of dirt and rock. Over thousands of years boulders and other loose material has worked its way down into the creek corridors.

During a forest fire, the protective chemicals that plants like chaparral produce to cover their leaves to mitigate water loss is released into the air and settles on the soil forming a water resistant coating. This hydrophobic layer, either at or just below the surface, prevents rainwater from being easily absorbed by the soil, dramatically increasing runoff during a storm. Depending on the intensity of the fire and amount of leaf litter burned, the layer can persist for several years.

Whereas most forest fires occur earlier in the year, allowing the often lighter rains of November and December to help soften the impact, the first storm after this fire was in January.

The storm brought with it several short bursts of high intensity rain, including one that dumped a half-inch of rain in five minutes; an event with a likelihood of happening only once every 200 years.

The intense burst of rain, combined with the effects of the fire on the landscape, triggered a debris flow of loose rocks, downed trees, and other material that was able to reach speeds of around 25 mph.

Because the density of the debris flow is close to the density of the boulders that have been washed down, the debris flow is able to essentially lift the boulders and carry them downstream at the front of the flow, like a floating wall of bulldozers scouring the canyon until it opens enough for the flow to fan out and the material to start to be deposited.

Slowly growing back on the scorched hills in the canyon are chamise, ceanothus, toyon, holly-leaf cherry, laurel sumac, and other chaparral plants, which anchor loose dirt in place and can help break up hydrophobic soils.

Continuing up the trail, roughly four miles from the trailhead, the trail arrives at a steep slide area that will need to bve repaired before it can safely be crossed. Unfortunately, it may be a year or more before it’s fixed. Trail crews will likely wait and see if subsequent rains undermine the trail further before investing resources in repairing it and instead focus on clearing and maintaining the lower trails that see more traffic.

From East Camino Cielo Road, the uppermost portion of San Ysidro Trail can be accessed and is in fair condition down to the slide area.

These mountains now present a challenging contrast between their beauty and the incredible amount of devastation and destruction the fire and subsequent debris flow have wrought on our community.

This article originally appeared in section A of the August 6th, 2018 edition of Santa Barbara News-Press

San Ysidro Canyon Trail debris flow Thomas Fire damage Santa Barbara montecito hike los padres national forest

San Ysidro Canyon looking downstream

Humboldt lily San Ysidro Canyon trail Santa Barbara montecito hike Los Padres National Forest

Humboldt lily with 28 flowers

Papilio rutulus western tiger swallowtail on Humboldt lily Lilium humboldtii san ysidro canyon santa barbara montecito los padres national forest

Swallowtail on Humboldt lily

Papilio rutulus a pair of western tiger swallowtail on Humboldt lily Lilium humboldtii san ysidro canyon santa barbara montecito los padres national forest


San Ysidro Canyon Trail debris flow Thomas Fire damage Santa Barbara montecito hike los padres national forest

Off-trail San Ysidro Creek


  1. Wow! Great shots of lily and swallowtails. 28 blooms shatters my personal record. Amazing!


    • I’d seen a lot of lilies going off in Lion Canyon behind Ojai, as well as in Romero Canyon, many with a fair amount of flowers lit up, but was blown away when I stumbled across this one. The one next to it has almost as many.

      I went back a couple weeks later to see if the ones at the top had opened up, but the heat we’ve been having took out most of the lower flowers and so neither one of them looked nearly as impressive.

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