One special element of the San Marcos Foothills West Mesa is the perennial spring in the northwest corner that provides the only natural, year-round water source on the entire San Marcos Foothills. The spring was likely used to provide water for cattle during ranching times.

At some undetermined point in the past, a long metal pipe was inserted in the hillside at the top of a small arroyo. This pipe apparently converted a natural seep into a controlled stream of water that falls into a bathtub, perhaps placed there at the same time. Water accumulates to as much as 7 to 10 inches in depth, depending on the state of repair of the tub that has cracks in the bottom.

During winter rains, the pipe produces a fairly good flow of water, but even in October of 2022, the spring produced approximately three gallons per hour. 2022 was one of many particularly dry years we have experienced during the current megadrought, so that much water being produced at the spring during the dry season is surprising.

Wildlife trail cameras have been placed at the site, including by Channel Islands Restoration (CIR) and many interesting animals have been caught on video using the spring. These include bobcats, coyotes, mule deer, skunks and several species of birds.

A barn owl occasionally visits the tub at night to take a bath and emerges with dripping wet feathers that he holds out like a vulture until the water can drain and be shaken off. European honeybees collect water in large numbers during the day.

In 2021, during the campaign to save the West Mesa from development, California red-legged frogs were found in the tub. Since that species of frog is listed by the federal government as threatened, the U.S. Fish and Wildlife Service relocated the frogs to San Antonio Creek, to ensure that they would not die if the spring dried up.

The Service also erected plastic fencing to keep people and dogs out of the sensitive habitat. The fencing was not attractive, and it was not received well, and someone tore it down. In 2022, California tree frogs bred at the spring.

CIR has received grant funding from two foundations to make the spring more friendly and useful to wildlife. For one, we will remove the leftover fencing at the site. We will also be carefully and methodically expanding the pool that is surrounding the bathtub, by installing more of the native rush plants that grows there and strategically placing a handful of sandbags.

Both measures should expand the pool and make portions of it as deep as the water that accumulates in the bathtub. In a second phase of the project, we will create a pond downstream of the seep with the same method.

In general, the more water that is retained in ponds the better it is for wildlife, but much preliminary study, consultations and permitting will be needed before the project can begin. CIR has many years of experience working in wetland areas, and we know the right people to consult about the habitat requirements for frogs and the right way to achieve our goals of expanding this rare wetland area.

Another consideration is how to address visits from people to the spring with their fur covered companions. Dogs have been caught on camera bathing in and drinking from the tub (even while frog eggs and tadpoles were present) digging in the mud and generally exploring the area.

Most wild animals react very badly to the presence of dogs, and they are even sensitive to dog scent left behind, even for many hours. A few coyotes visit the spring (usually at night), but they drink from the surrounding pool and ignore the bathtub. There are many more visits from dogs each day than by coyotes, and dogs have a much larger impact on the environment.

Ultimately, wetlands in dry Southern California are precious habitat and should experience as least disturbance as possible. Visits by humans and dogs should be discouraged since the spring is the only year-round wetland habitat on the entire Foothills.

As part of the spring enhancement project, CIR will be installing some interpretive signs that highlight the wonders of the unique habitat and encourage people and their furry friends from entering the spring. The current trail to the spring runs along the arroyo and is contributing to erosion there. 

The trail will be rerouted away from the arroyo, but ultimately it will be up to the good will of visitors not to disturb this sensitive habitat. In coming months, CIR will be regularly pointing videos of the wild animals that visit the spring.