Mount Tweto, Mount Arkansas, Mosquito Peak trip report


One of the more significant hikes I wanted to do on this trip would be a grand tour of the high peaks above the Mosquito Creek drainage. This would include Mount Tweto, Mount Arkansas, Mosquito Peak, two "soft rank" peaks that only satisfy the 300-foot rule if their saddles happen to fall at the low end of the possible range, and the lower but ranked, London Mountain. Doing all of the peaks in a day would be difficult for me, especially since I had done two longish hikes already this week. But, there were a variety of options and I decided to at least go for Tweto and Arkansas and then I could evaluate whether I wanted to continue on to other peaks.

The amount of hiking I'm doing is starting to wear on me a bit and with my sleep problems, I decided to take advantage of what looked to be a nearly perfect day in the mountains and slept in. I didn't leave Dillon until after 8am. I made my way over Hoosier Pass and through Alma. The turnoff for Park County 12 is a little over 7 miles south of Hoosier Pass and the road starts out decent. After 4.5 miles, you are at a junction with FR 419 on the left and a sign indicates that our road is 4WD ahead. The good news is that at least at the moment the road is passable in all but the lowest-slung normal cars to the useful trailhead for this hike that is indicated in several guidebooks at about 11530 feet. The gradient is not steep and the only problem is that there are a lot of rocks and you need to carefully follow the correct line in a few places to avoid straddling a too-tall one. But, my little Saturn sedan made it just fine to a junction at the 6.9 mile mark on the road. The Mosquito Pass Road continues on the left and quickly gets rougher after crossing a creek and a 4WD road starts on the right, which was the start of my hike. Two other vehicles were parked here, and one potential issue is that there is limited room to park without blocking the roads. I was glad to be able to park this high because I reconnoitered this road several years ago when I still lived in Colorado and wasn't sure about the first part past the "4WD" sign. It saves nearly 5 miles of hiking and something like 500 feet of gain, which would easily have made the difference between adding extra peaks onto the Tweto/Arkansas pair.

Lower valley from Tweto; I'm parked at
the junction left of the two ponds

I started hiking northward up the 4WD road at the ridiculous time of 0940. This goes against all of my advice for hiking in the high mountains of Colorado, but I was banking on the good weather and accepted that I might have to bail out early if that didn't come to pass. Thanks to the fair weather and the late start, I did not need to wear a jacket on the entire hike. I apparently missed a turn somewhere on the road because I ended up briefly going cross-country to stay on track. Otherwise, if you take the appropriate track, a road leads up to an old aerial cable that supported some mining a long time ago. This is at 12600 feet and it only took 45 minutes to hike the just under 2 miles to this point.

From here, you turn west and hike cross-country on the flats underneath the south slopes of Mount Tweto. My expected goal was the saddle between Tweto and Treasurevault. However, when I got to a point almost exactly due south of Tweto, I decided that I could save some distance and hike straight up the south face. The footing on the talus wasn't too bad and this is a reasonable shortcut.

I arrived on the summit at 1118 after just under 3 miles of hiking. There is a plaque at the summit commemorating the peak's namesame, Odgen Tweto, a geologist for the USGS who had worked extensively in Colorado. The peak was named not long after he died. Tweto comfortably makes the "Bicentennial" list of the 200 highest peaks in Colorado using the 300-foot rule.

Tweto plaque and ridge to Arkansas

The one-mile ridge to Arkansas looks fairly long from here and you can see the two false summits that lead to the somewhat steep true summit. Garratt & Martin's old guidebook warns that the traverse is rocky and slow and they also give it a "Moderate Climbing" rating which usually indicates some Class 3 moves.

The descent to the saddle between the peaks is steep, but not too bad. On the rest of the ridge to Arkansas, one often stays to the left of the ridgecrest to avoid some steeper sections and to try to skirt the false summits a bit. Although the ridge was slow, I didn't find anything harder than Class 2+, and that was mostly the last 20 feet or so at the summit. As you approach the summit, it looks very steep, but you can stay to the left side of the summit block and scramble eastward up boulders to the top. The ridge was certainly slow, though, and it took me nearly an hour for the traverse.

Final ridge to Arkansas

The views from all of the summits are similar, with particularly good views of the northern Sawatch Range and you can even see Snowmass Mountain and the Maroon Bells in the distance from some spots. It was already 1230, but I was planning more seriously to at least continue over Treasurevault to Mosquito Peak. Mount Arkansas only misses the Colorado top 100 list by 25 feet, still making it my second Bicentennial peak of the day and Mosquito would be the third.

Sawatch Range from Arkansas

The challenge is that you have to either climb back up the steep ridge to Tweto, or skirt Tweto on its steep western slopes. Garratt & Martin advise the latter, but after doing it, I'm not sure. The slope is quite steep for sidehilling and the footing is not always good. It does save you quite a bit of elevation gain because the most sensible route has you aiming for a point above the main Tweto/Treasurevault saddle that is only 100 feet above the Tweto/Arkansas saddle. This point is an extremely minor "saddle" that you can easily see from the Tweto/Arkansas saddle. In any case, I did the slow traverse and finally got down to the Tweto/Treasurevault saddle at 1340, a little more than an hour after leaving Arkansas.

Tweto sidehill Ridge to Mosquito

I took a 10-minute break here and just as I was leaving, a couple of ATVers showed up! The slope up to this saddle from my ascent valley isn't very steep, but I was surprised to see vehicles making it. I don't think there is a formal path and I'm not sure what the regulations are with regards to off-road travel here. I talked with one of the riders for several minutes and they also were from Arizona. However, coming in from Tucson, they (and their vehicles) were suffering a bit in the 13000-foot air and were unduly impressed that I had hiked up there.

The hike up the ridge to Treasurevault (the peak that just misses the 300-foot rule) is pretty easy because it is quite gentle, steepening only at the very top. I stayed up there for another 10 minutes in the still excellent weather with just a light breeze and scattered cumulus and cirrus clouds. The cumulus clouds peaked at about 50% towards the end of the hike. Mosquito Peak is just 0.45 miles by air from Treasurevault, but that includes a 280-foot drop and a 360-foot gain and I could see that this side of Mosquito looked fairly steep.

Treasurevault-Mosquito ridge

Indeed, the lower part of the ridge of Mosquito is very steep and loose. You can help yourself a little by following the mine "roads" that switchback up a bit of the ridge above some late model equipment. But, it was still plenty of work for me at this point. I reached my 3rd Bicentennial summit of the day (and 63rd lifetime out of the 200) at 1510. That's almost ludicrous, but it was clear by now that there were no weather concerns on this day. In fact, I recorded a full weather report on the summit just as a cloud covered the Sun and measured a temperature of 55F, and a relative humidity of just 10%! The wind only gusted to 12 mph, although I briefly had gusts above 20 mph when I first arrived, the only significant wind of the entire hike. The air pressure on my altimeter watch was 621 mb, as compared to the average sea level pressure of 1013 mb.

My plan at this point was to go ahead and descent the east ridge of Mosquito down to an unnamed lake at 12700 feet and then catch roads back to my car. Unfortunately, this didn't work out so well. I started down and ended up hiking down a finger of snow, which was a little easier than the talus. But, the ridge gets quite steep and had a fair bit of snow. This was not something that you would really want to try unless you really had to. So, I stayed to the right and ended up descending an awful scree and talus slope. If any ATVers were watching me from below, they probably thought I was nuts, but it wasn't actually dangerous. It was, however, very awkward, slow, and required much energy. I was trying not to cause too much erosion, but twice I set loose a small block of talus that tumbled about 100 feet down the slope, to give some idea of the steepness (around 30-40 degrees). At one lower point, I descended another relatively gentle snowfield just to get off the talus.

Frankly, I don't recommend my route at all, although if you can stay right on the ridge (which is recommended as a route by Garratt & Martin), maybe it isn't so heinous when dry. A better option might be to either cross the next ridge point, the unofficially named "Repeater Peak", another soft ranked peak and then heading down on the Mosquito Pass Road, or cross back over Treasurevault Mountain and descend the easy terrain of the ATVers from the Treasurevault/Tweto saddle. The steep section beneath the Mosquito/Treasurevault saddle was also protected by wind-blown snow and looked awkward to me even if someone had the requisite equipment.

The slope levels out down easier talus and tundra shortly above the 12700-foot lake. The linear distance from the summit to the lake is 0.57 miles, with a drop of just over 1000 feet and it took me about 45 minutes. But, that got me onto an old road. In fact, this road might be private, although the sign down at the junction with the Mosquito Pass Road was old and barely legible and the road was not gated. Perhaps another reason not to use this descent. In any case, I was back to the Mosquito Pass Road at 1624 with just over a mile to stroll back to my car, which I reached at 1651.

Although I was in a good mood from the success of the hike, I was pretty wasted. By the time I got back to my motel, I was as exhausted as I've been after a hike in a long time. In fact, I couldn't really recover in time to do another hike on this trip. But, I managed 7 13ers and this is the first time I've done 3 hikes with more than 3000 feet of gain within 6 calender days. (I guess that's not really amazing, but there are limits to my own self-abuse and when I lived in Colorado and Wyoming I didn't have to do hikes more than once a week.) This hike also gives me ascents of 24 of the 30 ranked 13ers in the Tenmile-Mosquito Range and 19 of the 25 13ers that are inside or on the border of Park County.

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File last modified: 06 July 2007

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