The most common type of forested lands in the national forests of the interior West are at warm, dry, lower elevations and are generally dominated by ponderosa pine. These are known as “frequent fire interval” forests because, before pioneers settled in these areas, fire historically occurred in them about every 5 to 30 years. (See app. II.) Because frequent fires kept these forests clear of undergrowth, fuels seldom accumulated and the fires were generally of low intensity, largely consuming grasses and undergrowth and not igniting the highly combustible crowns, or tops, of large trees. However, various human activities, but primarily the decades-old policy of suppressing fire in the national forests, have generally prevented fire from playing its historical role of limiting the forests’ density and clearing undergrowth and downed material. Without frequent fires, vegetation has accumulated, many tree stands have become denser, and less fire tolerant tree species have become more prevalent. (See apps. III and IV.) In these currently denser stands in the national forests of the interior West, many smaller dead and dying trees now form fuel “ladders” that conduct fire into the crowns of larger trees. Under these conditions, large, intense, and catastrophic wildfires have become increasingly numerous. For example, over the last decade, the number of acres of national forest lands burned by wildfires, more than 90 percent of which were in the interior West, has increased, reversing the trend of the previous three-quarters of a century. (See app. V.) Moreover, since 1984, the average number of fires annually on national forests that burn 1,000 acres or more has increased from 25 to 80, and the total number of acres burned (including nearby lands) by these fires has more than quadrupled, from 164,000 to 765,000. (See app. VI.) Since 1990, 91 percent of these large fires and 96 percent of the acres burned by them were in the interior West. According to the Forest Service, 39 million acres on national forests are now at high risk of catastrophic wildfire, and virtually all of these lands are located in the lower-elevation, frequent-fire forests of the interior West that are dominated by ponderosa pine. (See app. VII.) In recent years, the number of people living along the boundaries of the national forests has grown rapidly. (See app. VIII.) As a result, the increasing numbers of larger, more intense fires pose grave hazards to human health, safety, property, and infrastructure. Not only have lives been lost, but because smoke from such fires contains substantial amounts of fine particulate matter and other hazardous pollutants, the fires can pose substantial health risks to people living in this wildland/urban interface. Catastrophic wildfires threaten not only human health, lives, and property, but also infrastructure vital to nearby communities. For example, the 1996 Buffalo Creek fire, which burned several thousand acres and threatened private property in the wildland/urban interface southwest of Denver, left forest soils subject to extreme erosion. Subsequent repeated rainstorms washed what ordinarily would have been several years’ worth of sediment into a reservoir that supplies Denver with water. As a result, the Denver Water Board has estimated that it will incur several million dollars of ongoing expenses for dredging the reservoir and treating water—an amount that is several times the cost of fighting the fire. Finally, the growing number of large wildfires and acres burned—coupled with the increasing complexity of fire suppression in the wildland/urban interface—has greatly increased the costs of suppressing fires. From fiscal year 1986 through fiscal year 1994, the 10-year rolling average of annual costs for fighting fires grew from $134 million to $335 million, or by 150 percent, in constant 1994 dollars. (See app. IX.) Since 1990, 95 percent of these costs were incurred in the interior West. Moreover, the costs associated with preparedness, including the costs of keeping equipment and personnel ready to fight fires, are also increasing. For the 6 fiscal years from 1992 through 1997, these costs increased from $189 million to $326 million, or by 72 percent. (See app. X.) In recent years, the Forest Service has taken steps to address the increasing threat of catastrophic wildfires on national forests. In 1995, it announced its intention to refocus its fire management program on reducing accumulated fuels. Specifically, a 1995 internal agency report recommended increasing the number of acres on which accumulated fuels are reduced annually from about 570,000 to about 3 million by fiscal year 2005. In 1997, the Chief of the Forest Service said the agency intended to implement this recommendation and that the agency planned to continue reducing fuels on 3 million-acres per year through fiscal year 2015. By that time, the agency believes that it will have adequately resolved the problem of national forest lands being at high risk of uncontrollable, highly destructive wildfires. To implement its increased emphasis on reducing accumulated fuels, the Forest Service restructured and redefined its fiscal year 1998 budget for wildland fire management to better ensure that funds are available for these activities. In fiscal year 1998, it announced that the funds appropriated for reducing fuels would be allocated to emphasize protecting communities at high-risk in wildland/urban interface areas. The agency has also (1) revised its wildland fire management policy to more clearly spell out its responsibilities and reimbursable costs so that nonfederal parties can understand the consequences of not working with the agency to reduce the risk of wildfire on their adjacent lands and (2) proposed a number of pilot projects in collaboration with willing nonfederal partners to demonstrate the role of mechanical methods (including timber harvesting) of removing materials to reduce accumulated fuels. The Congress has supported the Forest Service’s efforts to reduce accumulated fuels by, among other things, increasing the funding for these activities in recent years. In addition, in acting on the agency’s fiscal year 1998 budget, the House and Senate appropriations committees approved a restructuring of the Forest Service’s budget to better ensure that funds are available for reducing accumulated fuels. The committees also earmarked $8 million in fiscal year 1998 for the agency and the Department of the Interior to begin a multiyear program, called the Joint Fire Science Program, to gather consistent information on accumulated fuels, methods of reducing them, the potential effects on other resources of these different methods, and their relative cost-effectiveness. The agencies currently lack adequate data in all of these areas and, in January 1998, the agencies issued a plan for conducting this research program. Moreover, as requested by the Forest Service, the Congress also authorized, in the agency’s fiscal year 1999 appropriations act, demonstration projects for reducing accumulated fuels. Many experts believe that these efforts by the Forest Service and the Congress are in a race against time. A 1993 assessment of forest health in the interior West, published in 1994, concluded that only a “brief window of opportunity” of perhaps 15 to 30 years exists for management intervention before damage from uncontrollable wildfires becomes widespread, setting the stage for a repeat of the current problems far into the 21st century. More than five of those years have already passed. Furthermore, the Forest Service’s current plans may significantly underestimate the number of acres on which fuels must be reduced annually to adequately reduce fire hazards. Specifically, the agency’s current and planned allocations of appropriated fuels reduction funding largely emphasize maintaining satisfactory conditions on lands in other regions of the country which currently have low levels of accumulated fuels so that conditions on these lands do not also become hazardous. Because maintaining current satisfactory conditions on these lands will require continued fuels reduction on about 1 million acres per year, only about two-thirds of the planned 3 million acre per year annual national fuels reduction effort will take place each year in the interior West, where virtually all of the most serious problems are located. As a result, as many as 10 million acres in the interior West may still have excessive fuel levels and may remain at risk of uncontrollable, catastrophic wildfire at the end of fiscal year 2015. The Forest Service, however, may be able to substantially reduce fire hazards without reducing fuels on all 39 million acres currently at high risk of catastrophic fire. For example, it may be able to construct fuelbreaks—i.e., areas where excessive fuels have been removed—in strategic locations to isolate areas with excessive fuels and thus limit the spread of large fires. However, the Forest Service has not yet developed a strategy for constructing fuelbreaks or implementing any alternative strategy to accomplish the same purpose. Thus, until the agency develops such a strategy, it will not have a basis for eliminating any current high-risk areas from its fuels reduction efforts or for assuring the Congress and the public that hazards to nearby communities will be adequately reduced. Several significant barriers must be overcome in developing a cohesive strategy to reduce wildfire hazards on the national forests of the interior West. The first of these barriers is that methods for reducing accumulated fuels can sometimes be difficult to reconcile with other legislatively mandated stewardship objectives, including meeting clean air and water quality standards and protecting threatened and endangered species. For instance, many agency and outside experts believe that, ultimately, avoiding catastrophic wildfires and restoring forest health in the interior West will require reintroducing fire through burning under controlled conditions to reduce fuels. However, winter snows limit the time available for burning, and dry summer weather creates a high risk that, given the massive levels of accumulated fuels, controlled fires will escape and become uncontrollable, catastrophic wildfires. Moreover, several officials and experts we spoke with believe that emissions from controlled fires on the scale needed to adequately reduced accumulated fuels would violate federal air quality standards under the Clean Air Act and that the act would thus not permit the desired level of burning either immediately or possibly even in the long term. The Forest Service and the Environmental Protection Agency, which administers the Clean Air Act, are currently conducting a 3-year experiment to better determine the impact of emissions from controlled fires.