Mosquito Pass

Leadville, Colorado (Lake County)

Last Updated: 12/01/2021
4.6 / 5 ( 57 reviews )
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Seasonal Closure
Typically Open: 07/01 - 12/01
Difficulty: 3-4
Length: 10.63 miles
Highest Elevation: 13185 feet
Duration: About 3 hours
Shape of Trail: Straight Through
Best Direction to Travel: West
Nearest Town: Leadville
Nearest Town w/ Services: Leadville
Official Road Name: Park County Road 12/Lake County Road 3
Management Agency: Pike and San Isabel National Forest
District: Leadville Ranger District


Highlight: Mosquito Pass
Mosquito Pass (elevation 13,185'), between Alma and Leadville, Colorado, is among the highest Colorado passes accessible to 4WD vehicles. The views from here are spectacular, especially in early autumn when the valley’s foliage begins to change color. The vibrant gold, amber, and green colors provide a stark contrast to the drab brown stone and paled grasses covering the high treeless ridges. Earlier in the summer, the alpine grasses and wildflowers are spectacular. However, check with the Forest Service District Offices because Mosquito Pass opens late due to snow blocking the road. Pike National Forest/South Park Ranger District (719) 836-2031 San Isabel National Forest/Leadville Ranger District (719) 486-0749


Route Information

Advanced Rating System

Recommended Vehicle:
Stock SUV with High Clearance and 4 Low
The turn and climb/descent on the rocky ledges at Waypoint 6 (Coomey Lake Spur) plus the switchback at Waypoint 10 give Mosquito Pass its difficulty rating.

Technical Rating

Typically, more rock or undulated road surface. Potential rocks and/or tree stumps less than 12" tall and/or vertical ledges less than 12" tall and/or near vertical ledges or waterfalls less than 24" inches. Tire placement becomes more difficult. Can be steep.
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Community Consensus

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Mosquito Pass is a very rocky road. From east or west, the lower portions are mostly dirt and gravel. As you gain elevation, the rocks become larger (6" to 8" diameter). Several segments of the road are entirely covered in loose stones up to 10" diameter, giving the sensation of driving on bowling balls. At the highest elevations, there are numerous switchbacks, but all are sufficiently wide so as not to require three-point turns. At these locations, trail surface is exposed bedrock. Mosquito Pass also includes a few shelf road portions that preclude passing.


1. Trailhead (0 mi)
The trailhead is at the intersection of County Road 12 and County Road 10, on the east side of Park City.
2. Intersection FS Road 696 (2.3 mi)
Keep right (east) at the intersection where the brown Forest Service sign indicates Mosquito Pass to the right.
3. Scenic Pullout (3.5 mi)
Continue straight past the pullout. This area is wide enough for five or six vehicles to make a pit stop.
4. London Mill Marker (4.5 mi)
Continue straight past the historic marker. You will see the remains of the mill structure to the west well before approaching the marker.
5. Intersection Champagne Mine Trail (4.7 mi)
Turn left (west) to follow Mosquito Pass Road. Alternatively, you can proceed straight (north) on the narrow trail which continues for approximately two miles. It is a rocky and winding diversion trail that terminates at the near-vertical base of a ridge between Mt. Tweto and Mt. Buckskin. There is an abandoned mine and a small collapsed structure here.
6. Coomey Lake Spur (5.8 mi)
Follow the broad Mosquito Pass Road. The spur heads north one-half mile and arrives at Coomey Lake. The turn and exposed bedrock makes this one of the more difficult points on the Mosquito Pass Road.
7. North London Mine (5.9 mi)
Continue straight at the North London Mine. There is adequate space here for a dozen vehicles to park, if desired, to view the remaining structure (Do Not enter or climb on the structure).
8. False Top (6.5 mi)
Proceed straight on the shelf road past the false summit.
9. Mosquito Pass (7.5 mi)
Arrive at Mosquito Pass. There is a historical marker with details about the site. The pass is broad enough for eight to ten vehicles to park temporarily.
10. Switchback (8.4 mi)
Proceed through the switchback. This point is one of the more significant obstacles on the road. It is a tight turn but wide enough that it doesn’t require backing. Before arriving at Waypoint 11 (Lakes), the road to the north is Birdseye Gulch
11. Lakes (9.6 mi)
Continue past this wide spot in the road, where the lakes are to your south.
12. End at Diamond Mine (10.7 mi)
The Diamond Mine is an active/operating mine. The road here is wide and there is a pullout with space for 10-12 vehicles.

Directions to Trailhead

Starting Point: Leadville

Mosquito Pass is a straight-through trail with start/end points in Leadville and Alma, Colorado. From Leadville, travel east on 7th Avenue which becomes Lake County Road (CR) 3 for approximately four miles to the base of Diamond Mine and a wide pullout. This is the western trailhead. From Alma, turn west off Colorado Highway 9 onto either Park County Road 10 or Park County Road 12.. These County Roads converge a few miles west of Highway 9 at the town of Park City. The point of intersection is the eastern trailhead.


Dispersed camping is allowed however many segments of Mosquito Pass are not suitable for camping due to grades/inclines. Suggested places to camp include Waypoint 6 and the broad gulch south of the False Top (Waypoint 8). One connecting road, Birdseye Gulch (between Waypoints 10 and 11), also permits dispersed camping. The US Forest Service maintains Kite Lake Campground about five miles north of Alma. There are additional US Forest Service facilities on the Leadville (west) side.
Camping: Mosquito Pass

Trail Reviews (87)

Questions & Answers (11)

Q: I will be staying in Breck next July and want to run Mosquito Pass with my SxS. I will be entering from Alma, where would be the appropriate place to park my trailer to unload? Thanks in advance.
–brandon (12/17/2021)
Q: I anticipate being in the area sometime in August 2021 and will check on the weather jconditions at that time. Otherwise, how is the trail specifically at WO6 and 10 for pulling a trailer (Offgrid about 14’ with 21” ground clearance). I’ll be driving a 4Runner Trail with lift and 33” tires. Thanks!
–Reese Kessler (06/02/2021)
A: Reese, Mosquito might not be the best pass to take with the trailer considering all of that, but another option for you is Weston Pass. It has WAY better camping options along it and your trailer would make the entire trek with no issues. Far less OHV traffic too. Fantastic views. It is just a bit farther south than Mosquito.
–Ryan Boudreau (06/07/2021)
A: Thanks for your responses. This will be my first trip with a trailer so I am planning on traveling on less challenging trails in Montana and Colorado in July/August just to get familiar with the handling etc. under varying circumstances. Perhaps I should turn around and backtrack at Mosquito Pass since that is my main objective? I will look for your and others August report before attempting.
–Reese Kessler (06/03/2021)
A: 14 feet seems long to me for those switchbacks, but I have never had a trailer of that size. I use to have an 11 foot Morris Mule and I wouldn't have hesitated taking it along those road. What are some other trails you have taken this trailer on?
–Ryan Boudreau (06/03/2021)
A: Hello, Reese. I don't think you'll have an issue at WP 6, but the length of your trailer gives me mixed thoughts about the switchbacks at WP 10 because they're pretty acute/tight angles almost forcing you to take a wider/the widest possible line. Your ground clearance should help with rock steps/ledges at WP 10. Stay 4LO and steady light throttle (climbing) and I think you'll be OK. Last suggestion is to stop and walk ahead to view the switchbacks so you can visualize your line. I should be up there before August, so watch for a trail report from me.
–Tracy Barker (06/03/2021)
Q: Doesn’t anyone know if the pass is open today? We plan to hit it from Leadville to alma
–Patrick Swiszcz (10/12/2019)
Q: How's Mosquito looking from the Alma side? We'll be in the area next week. Thank you in advance! :)
–Shawna (07/06/2019)
A: Snow is still blocking the trail short of the North London Mine. The full pass won't melt out until August.
–Ryan Boudreau (07/08/2019)
Q: Anyone know if the recent snows have closed the pass yet? Looking to do a run next weekend.
–stuart (10/22/2018)
A: Damn. That kinda kills my plan then. Thanks for the advise.
–stuart (10/23/2018)
A: I did Weston Pass (elevation 11,921ft) on Saturday, October 20th. There was snow above 9k feet, and it was packed and icy over the summit. We saw two vehicles (not part of our group) get stuck in the culvert to the side of the road (one slid off, the other intentionally tried to bypass). We thought about doing Mosquito Pass, but it was late afternoon (less than 3 hrs of daylight remaining) so we decided not to. I called the Leadville Ranger District this morning, and they said snow is forecasted today and tomorrow. Given that Mosquito is 2k feet higher than Weston, I recommend not attempting Mosquito Pass. You may try calling the South Park Ranger District to get more information about snow depth, forecast, etc.
–Tracy Barker (10/23/2018)
Q: Does anybody know current conditions for Mosquito Pass?
–Denise Diel Reynolds (06/20/2018)
A: September 15 2018: Open All the way through.
–Brian Ramirez (09/16/2018)
A: JULY 8 2018: communicated with Brandon Marlow who ran Mosquito Pass today; he reports the snow drift has melted and the road is OPEN.
–Tracy Barker (07/09/2018)
A: From Leadville to summit is open but very rocky. East side to Alma is blocked by snow from 1/2 mile passed summit.
–Donald Phelps (06/29/2018)
A: And by 7/24 I meant 6/24
–Brian (06/28/2018)
A: Was just up there 7/24/18. It is close but you still can't get up to the top of the pass from the east.
–Brian (06/28/2018)
A: I just posted a review below but the trail is impassable between waypoints 8 and 9 due to multiple snow drifts. Motorcycles can make it if you dont mind hiking your bike through the patted down path through the two easternmost drifts.
–Brandon Marlow (06/25/2018)
A: According to bushducks... 6/4/18 - Open and clear the whole way. No snow.
–John (06/20/2018)
Q: Is this trail still blocked by snow or is it finally passable?
–dwight (08/04/2017)
A: Dwight, according to Frank Whiston's trip report (see below near bottom of page, dated July 26, 2017), the road is passable.
–Tracy Barker (08/04/2017)
Q: I've got a 16" Tacoma Off Road with Cooper At3's. The truck is in stock form. Will this truck have enough clearance to make the treck up Mosquito mid-Sept?
–Andy (08/02/2017)
A: Thanks, great news. This will be my first real trail since getting into wheeling, It wont be the last and I'm sure my pocket book will be a lot lighter!
–Andy (08/03/2017)
A: Yes, your Tacoma will have adequate clearance for Mosquito Pass. There are only a few instances where there is potential for scraping/dragging, these are illustrated in the photos within the guide. Make good "line" selections to avoid centering over the largest rocks, and you'll breeze through it. Write a trip report afterwards!
–Tracy Barker (08/02/2017)
Q: We're finally here in Breck! How is Mosquito looking as of today? Hoping to go tomorrow :D
–Shawna (07/17/2017)
A: Snow Blocked at about false top on the east side. If you want to reach the top, start in Leadville.
–EVLXX (07/18/2017)
Q: Are ATV's allowed on Mosquito Pass?
–Sandy Rothe (07/04/2017)
A: Short Answer: Yes, but Park County restricts ATV use on County Road 12 east of South Mosquito Creek (map link below). Long Answer: The answer is complicated by the fact that Mosquito Pass Road is a County Road, and is bisected in vicinity of the "summit" between Lake County to the west, and Park County to the east. The US Forest Service also sets its Ranger District boundaries along a similar line, with Leadville Ranger District to the west, and South Park Ranger District to the east. Motorized Vehicle Use Maps (MVUM) produced for each Ranger District show the County Roads "for information and navigation purposes only and are not subject to designation under the Forest Service travel management regulation." Therefore, it is the counties which establish ATV use restrictions on the County Roads. On the east side, Park County permits ATV operation on County Road 12 west of South Mosquito Creek. (see map at On the west side, Lake County permits ATV operation on "all county roads that are not part of the state highway system", according to County Commissioner's Resolution 10-13, dated May 2010. (see Resolution at
–Tracy Barker (07/05/2017)
Q: We're heading to Breck in about two weeks...has anyone been up to Mosquito yet? Last June we couldn't get past the London Mine on the Alma side, so we're hoping going in July will be better :)
–Shawna (07/03/2017)
A: A friend reported last Saturday (June 30) that Mosquito Pass is open on the west side (Leadville) to the top, but the east side remains blocked due to snow above the London Mine. EDIT: note that the Lake County (Leadville) website still shows Mosquito Pass as "Closed" Last year, Mosquito Pass was reportedly open on July 25 (a Monday), after some "volunteer" shoveling effort. Coincidentally, myself and another trailsoffroad contributor were there the prior Saturday (July 23) but went elsewhere when we saw the FS signs indicating the pass was still closed.
–Tracy Barker (07/05/2017)

Writer Information

Tracy Barker

Mapping Crew - Colorado

Tracy is an outdoor enthusiast originally from north Alabama. His family moved to central Utah when Tracy was a child, and subsequently to southern Utah, where he fell in love with the Rocky Mountains. His favorite activities are family trail rides and camping with small groups. He started many years ago in his dad's F-150 pickup truck, and subsequently his own 4x4 acquisition, a 1975 Ford Bronco (in 1991).
For individual use only, not to be shared.