DELTA FORCE

For millions of years, water from the Colorado River flowed all the way to the Gulf of California. But not anymore.

The last 90 miles are dry, and that's where Francisco Zamora-Arroyo is pouring his energy. As director of the Colorado River Delta Legacy Program, he's fighting hard to bring the river back.

ABOUT 45 MILES SOUTHWEST OF YUMA, near the border of the Mexican states of Sonora and Baja California, is the Laguna Grande Restoration Area. Here, on a hot, humid mid-September afternoon, Francisco Zamora-Arroyo climbs down into a meander of the once-mighty Colorado River.

Water pours into the meander from a large irrigation pipe. Wheat chaff burns in the distance. Roadrunners skitter by, and a hawk circles overhead. Along the channel's banks, willows and cottonwoods that once had nearly disappeared from the area have regrown naturally - a key component of the goal that keeps Zamora-Arroyo coming back to this oasis.

For millions of years, water from the Colorado finished its 1,450-mile journey at the Gulf of California, but human intervention has changed that. All the river's water has been allocated for irrigation and other uses, leaving the Colorado dry for its final 90 miles. The change has affected people, wildlife and vegetation in the river's delta. More than 90 percent of wetlands there have disappeared because of a lack of river flow.

As director of the Colorado River Delta Legacy Program (CRDLP) at the Tucson-based Sonoran Institute, Zamora-Arroyo is working to bring the river back to a place that hasn't seen it in a long time. Zamora-Arroyo examines the new trees, pausing occasionally to point a telephoto lens at the birds that have flocked to the site. As he prepares to climb out of the meander, he stops to carefully replace a willow seedling he inadvertently uprooted. The seedling is one of thousands, but the act of righting it demonstrates a commitment to the river that he hopes to engender in others.

"One of the reasons the delta is in this condition is that people got disconnected from the river," Zamora-Arroyo says. "They don't know what's happening to the river. The younger generations don't even know there was a river. To them, 'Colorado River' has become just a name."

Zamora-Arroyo, 47, grew up in Mexico City. Frequent hiking, camping and fishing trips, led by his father, spawned a love and appreciation of the outdoors. And seeing Jacques Cousteau's weekly TV specials helped spur him to pursue a career as a marine biologist. As he was completing his bachelor's degree in oceanography at the Autonomous University of Baja California in Mexicali, Zamora-Arroyo developed an interest in "protecting nature, as opposed to just learning about it."

He geared his pursuits toward gaining a well-rounded perspective of environmental issues. He earned a master's degree in marine resource management and a Ph.D. in resource geography from Oregon State University. Now, he says, "I know enough of different fields to have an integrated view of the systems, the needs and the solutions."

Zamora-Arroyo started working in the river delta in 1998, shortly after the Sonoran Institute began exploring restoration opportunities there. Out of those explorations came the CRDLP, and in 2002, Zamora-Arroyo was hired as the program's first full-time staff member.

Today, the program has about two dozen employees. Its main purpose is to restore critical habitats in the delta for the benefit of people and wildlife. That includes the Cocopah Tribe, whose members have fished in the Colorado for centuries, and the Yuma clapper rail, one of the endangered birds that make their homes along the river.

But "restore," Zamora-Arroyo notes, is a loaded term. The program's goal is not to return the delta to the way it was before humans dammed the river. "We want to create a functional system - a network of restoration sites" that is sustainable yearround, he says. The CRDLP has restored 350 acres so far and plans to add another 400 acres by 2017.

Through a trust, the program buys and leases Colorado River water rights and dedicates that water to the river. In 2009, it worked with the water authority in Mexicali to create a wetland near a wastewater-treatment plant, allowing treated effluent to be returned to the river. It partners with state and federal agencies to promote ecotourism in the delta and create opportunities for people to get involved. And in 2012, it collaborated with the U.S. and Mexican governments, along with environmental organizations, to forge Minute 319, an international five-year agreement that guides the river's management.

The ultimate goal, Zamora-Arroyo says, is to secure 52,000 acre-feet of water for the delta each year. That "base flow" amount of water would keep the delta's groundwater table near the surface and allow plants to grow. In addition, Minute 319 led to the 2014 "pulse flow," in which the U.S. and Mexico released 105,000 acre-feet of water into the delta from Morelos Dam near Yuma. A pulse flow is designed to mimic the spring runoff normally seen on an undammed river. And the pulse flow is what caused those willows in the meander to grow.

About twice a month, Zamora-Arroyo commutes from Tucson to the Laguna Grande site and the Sonoran Institute's Mexicali office. Within a few minutes of his arrival, it's easy to see why frequent visits are necessary: There always are decisions to make and information to gather.

Workers scoop mud from irrigation trenches and chop down invasive salt cedars while Zamora-Arroyo and his staff discuss plans. The conversation, in Spanish but peppered with English phrases like "overhead costs," centers on building a small reservoir to irrigate some of the trees. "September is a difficult month for irrigation," he says. "The area is so big now that we need more certainty about water."

The pulse flow's effects are still being studied, but in the flow's final week, Colorado River water reached the Gulf of California for the first time since the late 1990s. During the event, people in the delta saw the once-mighty Colorado flow. Some of them were seeing it for the first time. Zamora-Arroyo visited with his 10-year-old son, hoping, as he did with his now-21year-old daughter, to impart the same connection to nature that Zamora-Arroyo's father instilled. "It worked for me," he says. "Hopefully, it will work for him."

Zamora-Arroyo's connection to the Colorado came in 1998, when above-average runoff allowed the release of water into the delta from upstream dams. He and two friends decided to traverse a stretch of the newly flowing river, much like a journey Aldo Leopold described in A Sand County Almanac. ZamoraArroyo and his friends, though, made the trip in "a cheap inflatable boat with a motor that didn't really work," and they got lost in the weeds and had to spend a night on the river.

Zamora-Arroyo counts the episode among his "near-death experiences," but he cherishes it. He got to see the river flowing and hear the birds that flocked to it, just as they had for millions of years. "That picture is always in my mind," he says. And as the Laguna Grande site has begun to match that picture, it's renewed Zamora-Arroyo's commitment to his work.

"It feels good to say, 'Look what we have done,'" he says. "It feels good to deliver." AH