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Delicate Vernal Pools Restored In San Diego County

Brenda Bennett examines plant life in and around a vernal pool in San Diego's...

Photo by Katie Schoolov

Above: Brenda Bennett examines plant life in and around a vernal pool in San Diego's Proctor Valley on April 13, 2017.

Those drenching winter rains that ended California’s six-year drought, painted San Diego’s Proctor Valley green this spring.

The Chaparral Lands Conservancy’s David Hogan stands in the heart of the expansive landscape and sees a window into the region’s past.

“Proctor Valley is special because it’s such a large relatively intact chunk of natural habitat lands so close to the city just east of the subdivisions in Chula Vista, right now,” Hogan said. “It’s really unique to have this much intact native habitat still around, anywhere close to San Diego.”

Coastal sage scrub wraps around the hilltops. A dusty gravel road cuts through the heart of the valley. Its washboard ruts violently shake vehicles that drive too fast.

What is found just off the road is what piques Hogan’s interest. Delicate ephemeral wetlands, known as vernal pools, can be found on the valley floor.

Video by Katie Schoolov

Ecologists are rehabilitating delicate habitat in San Diego’s Proctor Valley that is home to some of California’s most delicate plant and animal species.

Water brings the pools to life

These seasonal puddles are not around long, but when they are wet, the pools are centers of life.

“Those vernal pools, they fill up with water and last for two or three months and there’s all sorts of plants and animals that live just in those vernal pools and are adapted to those aquatic conditions,” Hogan said.

The pools are home to fairy shrimp, tadpoles and insects. Endangered plants like pin cushions, snorklewort and various grasses also live there. They endure impressive extremes. Wet pond-like conditions when it rains, long periods of bone-dry conditions when it does not.

Some plants and animals are so well adapted and specialized they can only live in this habitat.

The tire tracks that go through the middle of this pool, which is tucked a couple of miles up Proctor Valley Road, stand out. The old gouges are no more than a lingering reminder of a man-made disturbance. Plants have reclaimed this pool.

But other vernal pools in Proctor Valley have not fared as well.

Hogan takes a short drive south and stops at an area where the vernal pools have already dried out for the summer.

It is amazing that these pools are here at all, Hogan said.

“It was completely trashed when we first started here. Off-road enthusiasts had used it as a staging area, parking, campfires, parties, target-shooting,” Hogan said.

The pools, mud puddles as some saw them, were fun to drive through. People posted internet videos of their trucks roaring through the puddles.

Hogan says the gentle depressions turned into ditches, and the species associated with vernal pools disappeared.

But a seven-year-long restoration effort is turning back the clock.

“This is a vernal pool,” Hogan said as he knelt over what is now a dusty cracked basin. “It was an original natural pool, but it was extremely damaged. Lots of big tire ruts from off-road vehicles.”

The landscape here was flattened, reshaped and reseeded, said a proud Hogan who surveyed his team’s handiwork.

“This particular plant, right here, this bright green is the vernal pool pincushion plant. It’s found in very few places. It’s a federally listed endangered species. Also, a state listed species. So anyplace where we get an opportunity to establish a new population is a really good thing,” Hogan said.

Photo by Katie Schoolov

Vernal pool still holding water was in San Diego County's Proctor Valley April 13, 2017.

Most vernal pool habitat is already gone

Recovery efforts like these are critical for the species that call vernal pools home. That’s because an estimated 97 percent of all vernal pool habitat has been lost in California.

Biologist David Zoutendyk works for the US Fish and Wildlife Service at the agency’s Carlsbad office. He unrolls a large map on a conference room table.

“OK, so we’ve got a map here of all the historic vernal pool complexes in Southern California starting in LA going up into Ventura and even down into Mexico and as you can see, most of our pools occurred along the coast,” Zoutendyk said.

Vernal pools typically formed on the region’s flat mesas and that is one of the reasons they are no longer common.

“It was perfect,” Zoutendyk said. “When people came to develop San Diego it was flat land. Didn’t need to do a lot of grading. So that’s where the development occurred first.”

But the habitat is not completely gone. There are pockets of the pools scattered around the county. And federal officials are currently working on a plan to preserve land for vernal pool habitat in the city of San Diego. One of the biggest remaining vernal pool habitats is in Otay Mesa near the US-Mexico border.

Back in Proctor Valley, Brenda Bennett walks through the coastal scrub. This area is just across the road from the vernal pool restoration site Hogan’s team has mostly completed.

Bennett’s wide brimmed hat protects her from the sun. Knee-high leggings keep snakes from biting as she walks through the grass.

“Yeah, I’m heading over to a vernal pool. Right now it’s in the dry season,” Bennett said.

Bennett works for a company called Rocks Biological Consulting. She is in the midst of a dry season survey. Her trained eye scans the field and she hunches over a slight depression. She is looking for signs of a vernal pool.

“And so we have this very golden, shorter grass-like plant. Very common in vernal pools,” Bennett said.

She records the information on her clipboard and moves on. The information she and her colleagues gather will be compared to what was here earlier this spring when winter rains had just awakened these pockets of rare species.

“The hope is that these will be restored and the 'invasives' can be controlled and it’ll allow more of the rarer and endangered species to persist,” Bennett said.

This ongoing $1.7 million effort in the Proctor Valley will eventually restore and protect about 38 acres of land that historically had vernal pools.

Conservationist David Hogan concedes that this is just a tiny sliver of habitat, but he said it is an important sliver.

“So, we’re just trying to put a little section back, the way it was supposed to be. To protect that nature,” Hogan said.

Protecting that nature gives a host of fragile and delicate species a lifeline as San Diego moves forward into the future.

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