COPPER MOUNTAIN — Joe Hennessy of Wisconsin was zooming down an intermediate run at Copper Mountain on Friday when he bounced into a rut and tomahawked over his skis, dislocating his shoulder.

“It was a pretty nasty wipeout,” said his pal Sid Toering. “The snow isn’t that deep up there. . . . He hit a ditch that would typically be full of snow.”

As ski patrollers rolled a grimacing Hennessy — his arm in a sling but the pain fading thanks to a snort of Fentanyl nasal spray — into the slopeside emergency room, he became one of hundreds who have clogged high-country ERs in the past week.

The driest December in recent memory and a paltry snowpack are triggering surges in ER visits in ski towns as typical holiday crowds ski fewer and icier acres.

Typically the busiest week of the year for both resorts and emergency rooms, this season’s holiday week has been especially traumatic.

In Summit County, home to four ski areas that account for close to 4 million skier visits a season, emergency rooms have been hopping. The county’s four St. Anthony emergency rooms and mountain clinics have seen their busiest days of the year in the past week. Not coincidentally, the county’s four ski areas range from 16 percent open at Arapahoe Basin to 43 percent open at Breckenridge.

St. Anthony Medical Center in Frisco, for example, treated 74 patients in one day, up from an average of 50 a day during this holiday week in previous years.

Lack of snow is a problem beyond Summit County. In the Roaring Fork Valley on Tuesday, country music star LeAnn Rimes tumbled while snowboarding at one of the valley’s four ski areas. Rimes tweeted: “Tailbone hurts from falling on a stump that tripped up my board cause THERE’S NOT ENOUGH SNOW.”

Most of the state’s central mountain ski areas have seen meager natural snowfall in December, so most of the existing snow is manmade, which gets very slick toward the end of a heavily trafficked ski day.

Still, said Toering, waiting outside the clinic, “I don’t think it’s unsafe.”

While early-season skier visits won’t be reported until later next month, one indicator of traffic in the high country is the number of cars passing under the Continental Divide through the Eisenhower and Johnson tunnels on Interstate 70. Colorado Department of Transportation tallies for Dec. 20 through 26 show 223,126 vehicles passed through both tunnels, with 118,442 heading west. In the same week last season — a season that saw Colorado resorts post more than 12 million skier visits — 223,835 vehicles passed through both tunnels, with 116,548 heading west.

“With fewer runs open and the same number of skiers, there is a higher risk of collision and a higher risk of skier error,” said Denver attorney Jim Chalat, who specializes in ski-injury cases and has already signed up cases from injuries this season, including a child injured in a collision.

Chalat said traffic to his skisafety.com and skilaw.com websites is up 30 percent so far this season. He said collisions typically account for 5 percent to 10 percent of all ski-related injuries.

“In a low snow year, we see that closer to 10 percent,” he said.

By noon Friday at Copper Mountain, a makeshift cargo-truck ambulance was spinning nonstop, quarter-mile laps between the St. Anthony clinic and the snow, where sleds bearing injured skiers and snowboarders were awaiting transport.

On Wednesday last week, the nine-bed clinic — not counting the three extra beds stacked in the crowded hallway this week — saw 45 patients. The clinic typically sees 27 patients a day during the holidays.

“Wednesday was busier than any day last year,” said Dawn Sculco, a registered nurse and manager of the clinic, which was fully staffed Friday with three nurses, two EMTs, two doctors and two X-ray technicians. “We always see injuries based on the snow conditions. When it’s powder, we see knees. When it’s like this, we see wrists, shoulders, clavicles and concussions.”

Jason Blevins: 303-954-1374 or jblevins@denverpost.com

Seasonal rush

As of midweek — a few days before the crowded New Year’s holiday weekend — several high-country emergency clinics had seen their busiest days of the year.

• St. Anthony Medical Center in Frisco treated 74 patients in one day, up from an average of 50 a day during this holiday week in previous years.

• The St. Anthony Copper Mountain Clinic, which saw its busiest day of the past two seasons this week, is pacing 10 percent ahead of last season, with three of the busiest days of the season to go.

• The St. Anthony Breckenridge Community Clinic Emergency Center treated 60 patients in a single day this week, up from the typical 50 a day seen in the holiday week.

• The St. Anthony Keystone Medical Clinic treated 53 patients in a single day, up from the typical 50.

• Steamboat Springs’ Yampa Valley Medical Center saw 62 emergency department admissions Dec. 26 and 61 admissions Dec. 27. The same days last year saw 50 and 46 admissions, respectively. Most of the injuries were shoulder, hip and leg fractures, said hospital spokeswoman Rosie Kern.

• A spokeswoman at Denver Health’s East Grand Community Clinic and Emergency Center at the base of Winter Park ski area said the clinic was unable to tally this holiday week’s visits and compare them with last year’s.

Visits up

10% Increase in visits to St. Anthony Copper Mountain Clinic this season compared with last

Down and ouch

Different conditions create different hazards; common injuries when snow is scarce:

• Wrist

• Shoulder

• Clavicles

• Concussions