* Location: Carroll Cave, DR4
* Goals: Survey upper side lead in DR4
* Participants: Kohl Mitchell (leader), Caleb Mundwiller, Jack Rufener, Maria Rodriguez
* Time In: 9:45 AM
* Time Out: 12:00 AM
* Date: March 15, 2025
* Report By: Kohl Mitchell

After our camp trip in January, I set my eyes on the only remaining accessible lead in Lower Thunder River within reach for a long day trip – a miserable-looking upper crawlway off of DR4 last visited by Dan Lamping and Joe Sikorski in 2012. With a team of small cavers, we dropped in at about 9:45 AM on March 15, right after Bill Gee’s team entered to restock the rescue caches in Lower Thunder.

This was Maria’s first time in Carroll, and we planned on doing a little bit of tourism on our way out after survey, as I didn’t really have high hopes for our passage going anywhere significant. On the way to DR4, we stopped to take a look at the upper lead noted on the right side of the passage past Black Rock Riffles, which I remembered Alex Litsch investigating on a DL2 trip a couple of years ago. Jack climbed up to it, but decided it was going to be too sketchy to climb all the way up into.

We reached the entrance of DR4 at just after 11, and took a snack break before continuing into the passage. After a few hundred feet of increasingly nasty passage, we reached our lead on the left side of a decent-sized room. The tie-in station, RW1A, was nowhere to be found, but RW1 was still there, so we were able to reverse-engineer the location of RW1A using shots from RW1. With Maria in the lead, Caleb doing backsights, and Jack doing frontsights, we were able to make quick progress through the upper crawlway, which was consistently – barring a few small ceiling or floor ledges making it either a squeeze or a hunched sit – 2 feet high and 6 to 8 feet wide. To our pleasant surprise, the passage was not (initially, at least) the sloppy mud typical of Carroll, and instead had a much drier solid mud floor. Past station L10, Maria reported that no more tracks were present ahead of her, so we knew we were in virgin cave from here on out.
Beyond this point, we began encountering more and more water pools throughout the passage, and the mud was slowly becoming the goopy mess that we had expected to find. At L16, passage is nearly choked by an interesting partially eroded flowstone mound, and then the floor immediately drops off into a mud trough that one can nearly stand in, with 2 feet of air and 3 feet of water and mud, but passage quickly shrinks again to a belly crawl in pooled water for about 20 feet. With the passage getting wetter and nastier with every foot, and the survey book becoming thoroughly slimed, morale was reaching a low point, until we heard Maria report a pit ahead of her.

We hurried to take the last couple of shots before continuing ahead to meet her, at which point we were delighted to see our crawlway drop off a slope into a 12-foot high passage with a stream.
Ecstatic, we immediately took a break from the survey and scooped our booty to see what we had in store. To the left (downstream) of the entry point, it quickly choked down into a very tight low-airspace water crawl, but to the right, passage continued for about 100 feet before reaching an impressive 20-foot waterfall cascading over aesthetically pleasing black rocks with an accompanying dome, with an opening in the ceiling that may lead to upper passage.

We then reconvened to determine our plans. Ultimately, we decided that Jack and I would remain in this new discovery to finish the sketch of the crawlway and begin the survey of our new find, while Caleb and Maria would make the arduous journey back to the beginning of survey to retrieve our packs, which had been left there.

After I finished the final few shots of the crawl, Jack and I began surveying the downstream portion to the low-airspace, where we stopped in that direction for the time being. Jack began setting stations for the 100 feet or so of roomy passage between us and the waterfall, and as I finished the sketch of this portion I heard Caleb and Maria approaching from the crawlway.

After they recovered from their ordeal, and after Jack and I restocked on batteries, food, & water, we began the survey upstream in earnest. It took five longish shots to reach the top of the waterfall. Maria had been giving Caleb a Spanish lesson throughout the trip, so in keeping with that theme we decided to call the waterfall Cascada Negra. We also decided to call this area of passage that we were in Cutoff Creek, given its nature of being cut off from the main DR4 passage by the low airspace.

We left our final station at the top of the waterfall, where passage continues for at least 50 more feet at about 8 feet wide and 3-4 feet high, with breakdown-covered floors. We finished the survey with two small side passages at the base of the falls, one of which is a low crawlway that terminates after about 40 feet, and the other of which is an interesting side alcove that contains a breakdown-plugged swallow hole that forms a separate drainage from Cutoff Creek, as well as a possible continuation through a dig lead. With this, we called it a day and began to mentally prepare ourselves for the misery of returning through the upper crawlway.

Caleb, meanwhile, was forcing himself into the low-airspace downstream portion of Cutoff Creek. He made it past the initial squeeze, which was about 4 inches of airspace for 2-3 feet, and popped up into somewhat larger passage beyond. However, he wasn’t able to continue for long, as he reported that he could see 30 to 40 feet further down the passage and while it was slightly larger than the low airspace he’d just been through, he decided to leave it for next time.

In his words, “the creek stays on the same bearing from the first low airspace that was on our survey for probably 20 feet of easily traversable passage, then drops to low airspace, again at the same bearing, for another 20ish feet and then takes a hard left. It didn’t look any better or worse at the corner.”

Unfortunately, as we made our return through the crawlway, it had become substantially worse to navigate than our first trip through. Between the four of us going through the first time, and Caleb and Maria’s round trip earlier in the day, the mud and water that we’d brought with us had further liquefied the floors throughout the crawlway. Even the formerly dry, solid floors towards the beginning of the crawlway were now chunky brown soup. It may have just been our exhausted minds imagining it, but we also thought that the main passage of DR4 was far soupier than it was on our first trip through.

All thoughts of tourism banished from our minds, once we made it back to the main passage we beelined for the ladder. Maria, however, was particularly exhausted from her ordeals in navigating the crawlway four times in one day. As such, we decided to split up, with Caleb and Jack continuing on to the ladder to ensure that Bill and his party, who were staying topside overnight, weren’t concerned about our safety. Maria and I would make our way slowly and steadily to the ladder, finally getting to the top as the clock struck midnight. Sadly, the cave claimed quite a haul of gear from us – Caleb lost a flashlight (if anyone finds a Fenix hand torch in DR4, you know who to call) and an elbow pad, Maria lost a kneepad, and Jack lost a glove. Total survey would end up being just over 600 feet, with 346 feet in the upper crawlway and 257 feet in Cutoff Creek.