Can forest thinning save Santa Fe's watershed from catastrophic wildfire?

Since 2011, major wildfires in the Sangre de Cristo Mountains have burned ever closer to the edge of the Santa Fe Municipal Watershed, the source of much of the city’s drinking water supply. When fire does breach the boundaries—and experts say it’s just a matter of time—one of the Southwest’s most ambitious projects to fireproof a municipal watershed will be put to the test.

The question is whether the city's plan to remove thousands of trees from the watershed will be enough to withstand the sort of monster fire that could disable reservoirs and trigger floods capable of reaching downtown Santa Fe.

With winter snows draping local forests and filling reservoirs, wildfire seems like a distant threat. But a wet winter will stimulate new growth in a watershed already overstocked with flammable vegetation.

Bracketing the headwaters of the Santa Fe River, from the top of Upper Canyon Road to the base of Lake Peak, the 17,000-acre watershed forms a narrow, dog legged valley that acts like a siphon, capturing runoff from over 11,000 acres of adjacent mountains. The watershed is home to the city's two reservoirs, Nichols and McClure, and is the source of 30 to 40 percent of its annual drinking water supply.

It would be hard to find a more perilous place to store such an irreplaceable asset.

The watershed is surrounded by 2 million acres of national forest where drought and rising temperatures are causing wildfires to be bigger, more frequent and destructive.

Across the western US, the amount of land burned has tripled since the 1970s, and the average number of fires that have consumed 10,000 acres or more is seven times what it was, according to statistics compiled by Yale's School of Forestry and Environmental Studies. The situation is no different in northern New Mexico, where the largest wildlife in state history, the 2011 Las Conchas fire, did serious damage to the Santa Clara Pueblo watershed. Fires in the mountains east and west of Santa Fe burned roughly 300,000 acres during the past 15 years.

In a watershed, it's not what happens in a fire, but what happens afterward that can wreak the worst havoc.

Santa Fe could lose up to 60 percent of its reservoir capacity during the first year following a major wildfire and the boulder-strewn mudflows that would likely follow, according to the latest edition of the city's watershed plan. In the aftermath of such a fire, the amount of sediment washing down scorched slopes "would not only reduce the capacity of the reservoirs...but impair use of the water until the watershed healed." The plan goes on to say that it could take more than 10 years and cost up to $240 million to rehabilitate the watershed and the reservoirs If the warnings sound alarmist, the devastation is not without precedent. After the 2002 Hayman Fire in Colorado burned into Denver's watershed, the city spent the better part of a decade freeing up one of its reservoirs from the thousands of tons of debris that washed down barren hillsides destabilized by the fire. High winds had caused the fire to burn through areas of the forest that had been thinned.

Nonetheless, many wildfire experts believe that by "treating" a forest—thinning the trees by various means—the risk of catastrophic wildlife can be reduced, though not eliminated.

"As treatments accumulate over the landscape or are placed in strategic locations, they have the potential to make a significant impact on the behavior of wildfires," concludes one recent study by the Ecological Restoration Institute at the University of Northern Arizona.

The study cautions that "treated areas are not entirely fireproof and do not always serve as fire barriers. In the right conditions severe fire can burn through treatments or 'spot' over them."

Thinning itself is not risk-free when prescribed fire is used either to burn trees or brush. New Mexico's 2000 Cerro Grande fire, which destroyed more than 200 homes in Los Alamos, was a prescribed fire that burned out of control. Such incidents are rare, however. During the past 17 years, less than one percent of prescribed fires set by the Forest Service escaped control, according to the agency's National Fire Use Program. Of the 20 fires that did get out of hand between 2009 and 2011, two resulted in the loss of nearby buildings.

Santa Fe began taking measures to protect its watershed nearly a century ago after years of heavy logging and grazing had destroyed the vegetation, polluted the river and triggered floods. In 1932, the watershed was closed to public access, leaving faint traces of sheep trails, the remnants of a road built by convicts and the foundations of a long abandoned hunting lodge.

The closure did not put an end to all human sources of ignition. Over the years, the watershed became an illicit refuge for homeless camps, hunters and sightseers on foot or aboard all terrain vehicles.

The city's modern watershed plan, which was adopted in 1998, sought to tighten security but, more important, called for large scale thinning

across the lower onethird of the watershed.

Some local environmentalists  also argue the thinning is not worth the toll on humans. Yet, the cumulative effect of wildfire would be far greater.

The purpose is to create enough space between the remaining trees that fire will drop to the ground instead of spreading across treetops where it can be impossible to contain. The US Forest Service (USFS) began work in 2002, using controlled burns, chain saws and other mechanical means. The plan had been approved by a civic partnership including the city and county, the USFS, the Nature Conservancy, the Audubon Society and the Rio Grande Chapter of the Sierra Club.

Not all local environmentalists supported the plan, however, and some continue to oppose any thinning where trees provide nesting or foraging habitat for some 63 species of birds, among them the Northern Goshawk and two increasingly rare types of warbler. Some local environmentalists also argue that thinning is not worth the toll on humans: the smoke from prescribed fires, the carbon dioxide released from trees intentionally burned and the effects of chemical residue from the accelerants used to start prescribed burns.

Advocates of forest thinning say that when the work is done carefully, targeting small trees and creating openings in the forest that foster the regrowth of native grasses, the impacts on most wildlife tend to be short lived. Wildlife monitoring by the watershed partnership between 2003 and 2009 found that "most species remained unchanged, indicating resilience to thinning."

Ecologists who have studied the impacts of thinning on wildlife in western forests are not of one mind.

A recent paper in Global Ecology and Biogeography warns that widespread thinning changes forest structure "probably with negative consequences for biodiversity," while a concurrent article in the International Journal of Wildland Fire concludes that "most ecosystem compo- nents exhibit very subtle effects, or no measurable effects at all" from forest thinning.

As for the concerns about smoke, carbon dioxide and toxic residue, the simple rejoinder is that the cumulative impacts of a major wildfire and the tons of chemical slurry used to fight it would be far greater.

The Natural Resources Defense Council, one of the country's leading environmental organizations, has just released a report cataloging the health effects—including asthma, pneumonia and heart disease —of exposure to the smoke from wildfires. The study found that virtually all of New Mexico's population is exposed to medium and high density smoke from wildfires for a few days to several weeks a year. The study, however, does not address the comparative hazards of smoke from prescribed burns.

By 2009, the City of Santa Fe and the USFS had completed much of the thinning work called for in the 1998 plan. The Forest Service had cut and burned trees on 5,400 acres at a cost of $8 million in state and federal funds. Visible today, the results are dramatic. Thinned areas resemble parkland with clusters of stately ponderosas freed of undergrowth and separated by broad aprons of grass. The forest density was reduced from several hundred trees per acre to 100 or fewer. Today, as part of the plan, the Forest Service continues to burn piles of branches and trees that were cut during thinning operations.

Experts hired to assess the work believe more thinning needs to be done.

William Armstrong, the USFS fire and fuels specialist who has overseen much of the thinning, would have preferred to give the forest a shorter haircut. As he stands next to McClure Reservoir on a recent visit, Armstrong says if he had his way there would be nothing left there but grass. As extreme as it might sound, such a scenario is not unprecedented. At Los Alamos National Laboratory, for example, the ground around waste storage sites has been shorn of trees and shrubs to keep fire away from highly flammable toxic materials.

Ellis Margolis, a research fellow at the University of Arizona's Laboratory of Tree-Ring Research who was retained by the Santa Fe Watershed Association, agrees with Armstrong that more thinning is needed. "The upper Santa Fe River watershed is arguably the most at risk, high profile municipal watershed in the southwestern US," he wrote in a 2009 report published in Forest Ecology and Management.

If more thinning is done, he says, "the probability is much higher that if fire came into the treated area, it would lay down" and thus be easier to control.

Margolis went on to Margolis went on to say that the watershed remains "at high risk of the type of event that could destroy the water supply infrastructure and flood the historic heart of the city."

Margolis has studied the history and frequency of fire in and around the Santa Fe watershed and doesn't believe that fire can be kept out. But if more thinning is done, "the probability is much higher that if fire came into the treated area, it would lay down," and thus be easier to control, he tells SFR.

The 2013 revised watershed plan does call for more thinning.

The work is to be conducted over the next 15 years at an additional cost of $5 million, much of it to be borne by the 30,000 households that use the water.

The next phase of work could well be more controversial than the first round of thinning. East of McClure Reservoir, and deeper into the mountains, it would target 2,900 acres of mixed conifer forest on steep slopes inside the boundaries of the Pecos Wilderness.

Sandy Hurlocker, the Forest Service's ranger in charge of the project, says he would like to start work on the new area next spring but concedes it might not be possible given the challenges posed by the location—a federal wilderness where wildlife protections are stricter and the use of machinery is prohibited except in emergencies.

Local environmentalists are particularly concerned about the Forest Service's proposed thinning strategy. Hurlocker and Armstrong want to deploy helicopters to ignite controlled burns from the air. The alternative, sending people up the nearly vertical slopes to start fires by hand, would be impractical and unsafe.

One local group "Once A Forest" has already expressed its opposition. Another, WildEarth Guardians, which formally opposed the first phase of thinning, has not indicated whether it will do so again but is clearly not a fan of the Forest Service's proposed work plan.

"We have reservations about using helicopters in wilderness. If the Forest Service can't do it by hand, it should consider not doing it all," says Bryan Bird, the group's program director.

The debate over how best to manage the watershed does not end at its boundaries. In 2006, the Forest Service began advocating a 965-acre thinning project along densely forested ridges in Hyde Memorial State Park and Black Canyon that abut the watershed's western boundary.

Armstrong assessed the vulnerability of the area to fire in 2005 in a report based on computer modeling. The modeling assigned a 95 percent probability of a fire of larger than 1,000 acres within 20 years.

"Ignition sources are common and of particular concern are the number of campfire circles, abandoned homeless camps and dispersed recreation sites," Armstrong wrote. "Even without human ignition sources, lightning is a common phenomenon."

Craig Allen, a research ecologist with the United States Geological Survey, echoed Armstrong's concerns in a recent presentation to the Santa Fe City Council. Allen, who lives in Santa Fe, is an internationally recognized expert on the role that drought and climate change are playing in wildfire behavior.

The gist of his message was that in a matter of minutes southwesterly winds could carry a wildfire from Hyde Park, not just to the watershed but into adjacent residential neighborhoods and into the heart of Santa Fe's most popular recreational terrain.

Such a fire "could turn the green back door of Santa Fe into a bunch of sticks," says Allen. "It's disturbing no action has been taken given the consequences."

The Forest Service's proposal to thin Hyde Park has lain dormant since it was successfully appealed by WildEarth Guardians and other environmentally minded residents, including veteran activist Sam Hitt, who regards much of the prognosticating about monster fire in or around the watershed as alarmist in the extreme.

"The chances of a crown fire occurring there are vanishingly small, less than one tenth of one percent in any given year," he tells SFR.

Hitt invokes the work of University of Wyoming Geographer  William L Baker, among other contrarians, who has written extensively about fire behavior in southwestern ponderosa pine forests similar to the one in the Santa Fe watershed.

Writing in The Open Forest Science Journal, Baker and co-author John Rhodes contend that high severity fires are far from inevitable, and that even in those ponderosa forests that do burn relatively frequently there is only about a 50-50 chance that thinning will reduce fire severity.

Despite the contentiousness, there is still room for agreement within Santa Fe's watershed. It begins around 9,000 feet where the Santa Fe River carves its way through a narrow, high elevation canyon and where the ponderosas give way to spruce and fir.

Forest policy is not contested there because the policy is to leave the area alone. No one is suggesting doing any thinning there or on the thickly forested slopes that frame the eastern border of the watershed.

It is roadless high country with few if any other ways to gain access. And even if personnel and machinery could make it up, the danger is that a controlled burn would explode into the type of conflagration that could do irreparable damage to the watershed downstream.

The watershed's high-elevation forest is so flammable because it hasn't burned since the late 1600s, the last time there was a drought as severe as the current one, according to Margolis.

Sooner or later, when fire does come to this place, lightning will probably provide the match, as it did in last summer's 11,000 acre Jarosa Fire, several miles to the north in similar high elevation spruce and fir.

"The upper watershed, in the spruce and fir, is going to burn. Up there, it's inevitable," Hitt says.

The question no one can answer is whether such a fire would be followed by rain and landslides severe enough to cripple the reservoirs below. Armstrong points out that the Jarosa Fire did not lead to devastating landslides.

Most experts would agree with Hitt that fire tends to be good for a forest, stimulating new growth and new habitat for wildlife. The consensus these days is to let fires burn, especially in wilderness. But a fire in a municipal watershed is another matter, even a fire that moves in the opposite direction of civilization, away from the reservoirs and infrastructure that capture and clean the water.

As the authors of the watershed plan have warned, a fire often causes the worst damage after the flames are out, when monsoonal rains pummel the scorched ground and unleash tidal waves of mud and rock.

Santa Fe is lucky to have other sources of water: two municipal well fields and a share of Colorado River water that is diverted across the Continental Divide and down the Rio Grande to Santa Fe and Albuquerque. Hypothetically, the city can rely on these sources if the watershed doesn't deliver either because of fire damage or drought. Even if the watershed doesn't burn, there is nearly an 80 percent chance that it won't yield its share of the city's water in a long drought, says Margolis.

Unfortunately, the city's two other water sources are also vulnerable. Santa Fe has been forced to rest its wells in the past after pumping exceeded the natural rate of recharge and threatened to do damage to the underlying aquifer. Storms following the huge Las Conchas fire in 2011 washed so much debris into the Rio Grande, it was not feasible to treat the water, and the city had to halt its withdrawals from the river for nearly three weeks. Even with all of its sources, the city warns in its long range water plan, (published on Santa Fe's official website) that supplies will fall short of meeting projected demands by 2021. Moreover, by 2045, the city projects its water deficit will rise to 2,700 acre feet a year, the amount needed by 10,000 families. The long range plan takes into account conservation efforts that so far have led to a 25 percent reduction in per person water consumption. The plan also assumes that the city's strategy for protecting the watershed and its reservoirs will succeed.

Spring winds and summer lightning will test that assumption.

Frank Clifford is a Santa Fe resident who was a staff writer and editor at the Los Angeles Times for 25 years. He edited environmental news there from 2001 to 2007.

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