As Peter Moyle perched himself on a short bank of Putah Creek, the better to see the life forms rippling its dark green waters, a swimmer with a determined butterfly stroke bobbed by. 

Next, a gaggle of teens carrying pink and yellow floaties strode past on the woodsy hiking trail hard by the stream. Couples, families and groups of friends followed. On a Sunday afternoon as bright as new Sterling silver, with the pandemic lockdowns loosened, Putah Creek, at the southern edge of the University of California, Davis campus, was the liveliest spot in town. 

No one paid much mind to the Mark Twainish gentleman in the khaki pants and wide-brimmed hiker’s hat, looking for “fish life” at the water’s edge. No one knew he had helped make their day. Putah Creek was literally a pit in the 1970s. 

UC Davis mined it for gravel and its banks were trashed with wrecked cars. Moyle—Dr. Moyle or Professor Moyle to marine biology students at UC Davis for over four decades—led a community/campus effort to bring the neglected eyesore back to life. 

If fish biologists became famous, celebrated for saving ecosystems, Moyle, the leading expert on California’s waterways and native aquatic species, would be a household name. His research has helped revitalize rivers, creeks, marshes and life all around them—and at 78, he is still at it. 

He still goes out on a boat once a month to survey fish, still writes (after 11 books and more than 250 peer-reviewed articles) and still testifies to legislators in Sacramento about the state of the state’s waters. In fact, the mild-mannered Moyle is involved in California’s biggest water war, one his efforts to save an ecosystem he unwittingly helped trigger. 

Moyle first sounded the alarm over a declining native freshwater fish, the delta smelt, over 30 years ago. The three-inch semi-translucent fish lives only in the San Joaquin-Sacramento Delta, the network of islands and canals that is the hub of the state’s water supply system. Efforts to save the delta smelt and other threatened native species have led to limits on water pumped from the delta to the vast farm lands and cities hundreds of miles to the south.

The agricultural industry has cried foul and complained bitterly that California is favoring fish over farmers. President Donald Trump, who counts the agricultural lobby as one of his biggest donors, has taken to predicting California will have to start rationing water to save “some kind of tiny little fish.”

But Moyle calls the delta smelt a scapegoat for poor water management and a bellwether for an ecosystem sickened by overuse and major droughts. Several other fish species native to the delta, he notes, are also listed as threatened under the federal Endangered Species Act, including the longfin smelt, green sturgeon and spring run Chinook salmon; others, including the splittail, San Joaquin Chinook and Sacramento perch, are in serious decline. With climate change, Moyle added, “it will only get worse.” 

Longer droughts, bigger floods, warmer water temperatures and more erratic flows of water into the delta spell danger for native species, Moyle said, especially when they are competing with non-native invasive species for the same habitat. When his research team analyzed all 122 native fish species in California and their vulnerability to climate change, it found that 83 percent were either critically or highly vulnerable to becoming extinct within the next 100 years. Only 18 percent of alien species face the same fate.

Still, even an ecosystem with competing interests could be helped, Moyle added, through a coordinated commitment among all agencies and interests involved. “We’ve got to integrate conservation,” he said, “into the places humans live and work and play.” He calls the approach “ecological reconciliation,” where “coequal” goals are met. For the delta, it would mean finding ways to meet the needs of farmers, local communities and native species like the delta smelt. 

‘Ecological Reconciliation’ in Practice

Moyle likes to discuss ecological reconciliation as a solution to the state’s water problems because he has seen—indeed, helped make—it work. An early triumph occurred at the McCloud River Preserve, near the top of California. 

In the 1970s, the Nature Conservancy asked Moyle to examine how best to preserve the McCloud’s rainbow trout and its watershed. His extensive biological study found that part of the preserve could be opened to public use with careful management. Anglers could still practice their sport and help save the rainbow trout by practicing catch-and-release fishing, a little known practice at the time.

Following Moyle’s plan, three miles of the river were opened in 1976, providing recreation for the public, preserving the trout and revitalizing the ecosystem. Fly Fisherman magazine, which named Moyle its “2020 Conservationist of the Year,” credits him for making the McCloud one of the world’s premier trout streams, and catch-and-release fishing the standard for the sport all over the world.

Putah Creek’s renewal began when Moyle and a group of landscape architecture students at UC Davis decided to make the stream’s restoration a project at the same time that a group of local birdwatchers said they, too, wanted to restore the creek.They formed a group, the Putah Creek Council, which found out that the Solano County Water Agency was releasing water from the creek to farmers, leaving the stream bed virtually dry. Attempts at negotiating water releases to the creek failed and the council sued the agency. Moyle took the witness stand to explain how the creek could be brought back to health by managing its water flows.

The Putah Creek Council won the suit. The Solano County Water Agency appealed but during the appeal process, in 2008, it reached an agreement with the Putah Creek Council that would work for everyone. Moyle’s plans for the creek were implemented and the creek has enjoyed assiduous attention in the last decade, winning over early detractors. It is listed at the top of lists of “things to do in Davis.”

The Scholar-Activist

Growing up in Minnesota, land of more than 10,000 lakes, Moyle knew that biologists could change the world. His father, John Moyle, was a leading plant biologist at the University of Minnesota’s Cedar Creek Ecosystem Science Reserve, an internationally known field station. He helped pioneer the discipline of ecology, little known at the time. 

He also developed scientific research methods for fish and wildlife management at the Minnesota Department of Conservation (now, the Department of Natural Resources) that are still used today. Peter Moyle recalls an idyllic childhood steeped in adventures in Minnesota’s waters.

Peter and his two sisters followed in their father’s footsteps and became wildlife biologists. (One is retired, the other, deceased.) Moyle calls his only brother, whose interests led to a career in diplomacy, “the black sheep.”

Peter Moyle received a Ph. D. in Zoology from the University of Minnesota. After three years at Fresno State University, he arrived at UC Davis in 1972, where he became interested in the delta smelt, a fish that was little known. Moyle started a monitoring program for the delta smelt in 1979, when its numbers were abundant. 

By the mid-1980s, Moyle noticed the fish’s numbers had seriously declined. He petitioned California to list the delta smelt under the state Endangered Species Act in 1989. His research provided the basis for the delta smelt eventually becoming listed as threatened under the federal Endangered Species Act in 1993. California followed with its own threatened listing that same year. The state relisted the delta smelt as endangered in 2009.  

Moyle is a distinguished professor emeritus at UC Davis, where he remains the associate director of the Center for Watershed Sciences, which he co-founded. He still lectures regularly (several of his talks are on YouTube) and has no plans to retire. 

For a scientist, becoming involved in a high-stakes political battle may be part of publishing research findings, but it is no fun. The president and other politicians supported by the agriculture industry have continually undermined Moyle’s research in the delta.

In Trump’s first interview after announcing he tested positive for the coronavirus, he claimed that California “sends millions of gallons of water out to sea, to the Pacific” because “they want to take care of certain tiny little fish that aren’t doing very well without water, they have farms here and they don’t get water. It is so ridiculous they’re taking the water and shoving it out to sea.”

Trump last year forced the Environmental Protection Agency to rewrite the analysis that led to the Endangered Species Act protections in the delta. Then, in February, he issued an executive order based on the revisions that called for more water flows to the Central Valley.

The order was halted by a temporary injunction after a coalition of environmental groups, and the state attorney general, went to court to argue that it violated California’s endangered species protections.

Only 1 percent of the water pumped to Central Valley farm lands was diverted to protect endangered species, Moyle said. Routine actions to protect water quality and maintain pumping infrastructure have had more of an impact on the water flows. Still, Trump’s assertions were irritating.

“As Trump showed so well in the ‘debate,’ he is an ignorant bully,” Moyle said, ”so a small helpless little fish is a perfect target for him.”

What Can Be Done at the Delta

Competing interests have debated the fate of the Sacramento Delta—who gets its water, how much, how best to protect and replenish its fish—for decades. In a recent piece in CalMatters, Bruce Babbitt, a former U.S. Secretary of the Interior, suggested the delta needs “a grand bargain.”

All the parties need to achieve a consensus, he said, confirmed in legislation.The consensus  would apportion Delta water between exports, or the water pumped to farmers and cities in Southern California, and an adequate ecological flow, or the water needed to maintain the native ecosystem. Babbitt’s proposal is similar to Moyle’s concept of “ecological reconciliation,” though both Babbit and Moyle question whether an agreement that satisfies all concerns can ever be reached.

The latest proposal to solve the conundrum, from Gov. Gavin Newsom, calls for a 30-mile-long underground tunnel or aqueduct, the largest water project in California in decades. It would divert water from the Sacramento River beneath the fragile wetlands, waterways and islands of the delta to an artificial body of water. From there, it would send the water through state aqueducts to Southern California and through federal channels to agricultural lands in the San Joaquin Valley. If it sounds like Rube Goldberg designed it, that is typical of the vast infrastructure in the delta. It is largely considered among the most manipulated bodies of water in the world through its dams, canals and massive pumps.

Newsom’s plan, called the delta conveyance tunnel, replaces a plan for two 30-mile tunnels that Jerry Brown proposed, only to be shot down by the legislature and competing interest groups as too expensive and risky. Newsom’s tunnel would cost $11 billion, $6 billion less than two tunnels, but the plan is short on details and years from being worked out, let alone built.

Moyle said he has “quietly supported” a tunnel project in theory, based on two assumptions. “First is that ag and urban interests will get a lion’s share of the water no matter what,” he said. His second assumption is that at some point, the levees that hold up the islands in the delta are going to collapse due to a major earthquake, floods or rising sea levels. 

Some islands are already 25 feet or more below sea level and beneath the water level in the surrounding channels. Climate change will increase sea level rise, increasing the pressure on the levees. If major levee collapse occurs, and the pumps in the delta start sucking up salt water, Moyle said, “there will be a canal built anyway, as an emergency measure.”

California’s freshwater fish are in crisis, Moyle said. In the future, California may have the same fish in its waters as everywhere else, with hardly any native species, and its ecosystems will be poorer for it. What’s needed is a statewide strategy of ecological reconciliation. “We’ve got to integrate conservation in the places that we humans live and work and play,” he said. 

Concrete steps that have worked for other waters, he said, include creating a favorable water flow regime, or plan, that regulates high and low flows to favor native species. He would also love to see reductions in key alien species, improved water quality, and expanded tidal habitats. And all of that, he said, must be done with a plan that also delivers water to humans.   

“It’s not too late to change a lot of things,” he said, “but people really have to want to do the work.”