The monstrous San Isabel National Forest is made up of big mountains and forests challenged by little bugs.

With more than 1.1 million acres stretching across central Colorado, from the headwaters of the Arkansas River above Leadville down to the Spanish Peaks region in the southern part of the state, the San Isabel is a sprawling set of mountains and wilderness areas.

At 1,120,233 acres it ranks as the sixth biggest national forest in the state out of 11. With the Sawatch Mountain Range and the Sange de Cristo Range in its boundaries, however, the San Isabel makes up for what it may lack in size with elevation. Not only are 19 of the state’s 53 14,000-foot peaks here, many of the state’s tallest mountains are also located in the forest.

Mount Elbert, at 14,440 feet, is the state’s highest while 14,421-foot Mount Massive has more terrain above 14,000 feet than any other mountain in the lower 48. Mount Harvard, at 14,421 feet, anchors the Sawatch’s Collegiate Peaks near Buena Vista. .

The mountains in the Sangre de Cristo Range are about as tall but a bit more rugged and remote. The Sangre de Cristos have another seven 14,000-foot peaks, including the fourth tallest point in the Rocky Mountains, Blanca Peak, 14,345.

While hiking to the top of 14,000-foot mountains is a popular activity, the forest has more than just towering mountains. Other activities include everything from hiking, fishing and camping to skiing, rafting and riding off-highway vehicles.

In summer, the Arkansas River is a major attraction.

The Arkansas is the most commercially-rafted river in the United States and also boasts a robust fishery. The river boasts 102 of Colorado’s 322 miles of Gold Medal trout waters, stretching from Leadville to Pueblo Reservoir.

In winter, Monarch Mountain west of Salida and Ski Cooper north of Leadville draw skiers and snowboarders. Neither is a mega resort, but what they lack in lifts and crowds they make up for with ample snow. Monarch averages 350 inches of snow a year. Cooper, meanwhile, averages 260 inches, but with a base elevation of 10,500 feet, it stays dry and light. Cooper added a new lift for the 2019/20 season, opening up steep terrain in the Tennessee Creek Basin.

During winter, snowmobiling, snowshoeing and cross-country skiing are featured on designated routes and seasonal roads while ice fishing is popular at several lakes and reservoirs including Twin Lakes and Clear Creek.

As big as the forest is, one of the biggest challenges it faces is from an insect. The spruce bark beetle has affected more than 1.84 million acres of trees around the state, according to the Colorado State Forest Service, and both the Sawatch and Sangre de Cristo ranges had severe outbreaks continue last year, as did other mountain ranges across the state.

Managing the dead trees the beetles leave behind is one of the biggest challenges the pesky insects present to the forest, said Lisa Corbin, timber program lead with the San Isabel National Forest.

Getting to the wood before it degrades is one challenge. Another is that the steepness of some slopes makes it inaccessible for the Forest Service and timber contractors to go in and remove them.

Aside from a visual aspect, most people visiting the forest won’t notice a large impact from the beetles. When venturing out in the woods, however, hikers need to be aware of standing dead trees.

“People need to recognize the hazards of these trees — they will fall,” Corbin said.

The Forest Service has a few tools it can use to help stop the spread.

It can log trees to manage the beetles, use prescribed burns or let natural fires take their course. Since the Decker Fire that burned just south of Salida in September-October 2019 was essentially consuming dead and downed fuels, firefighters on site dug lines to contain the blaze, monitoring it while letting the fire burn.

“Fire is good,” Corbin said. “It’s a natural part of the ecosystem and helps replenish nutrients; it’s important to have that component available to use.”

At Monarch, the ski area has been working with the Forest Service to identify dead and dying trees, cutting them down, turning some into lumber and others into firewood, while making the ski area safer.

Corbin said the beetles started moving north in the early 2000s. Unfortunately, they can move faster than the Forest Service can manage them.

“We can’t stop it through management,” she said about their spread. “It’s going to take natural events.”

The Forest Service has approximately 230 permanent employees to manage the San Isabel. In summer the Forest Service also hires seasonal employees. The numbers vary from year to year, but can account for up to half as many — and sometimes more — of the permanents, said Julie Bain, acting San Isabel public affairs officer.

Most employees are professional resource managers, specializing in fields like fire, timber, forestry, wildlife, special uses, water and archaeology. All eight ranger districts within the forest also have their own district rangers.

The forest’s average annual budget is about $21 million, Bain said. Funded primarily by the federal government, revenues come from fees for things such as recreation sites, permits, livestock grazing, parking and timber sales and totals about $2.5 million.