The backyard canyon Holladay
The nearest drainage to Holladay that is not protected drinking water
Neffs Canyon, and the shaft beneath it.
A small lot at the end of a residential street opens onto a Forest Service trail the agency publishes at about 4.44 miles and 1,821 feet of gain, where a leashed dog is welcome because this drainage is not watershed. Underneath it runs a cave 1,163 feet deep that has been gated shut for decades. Here is the walk, the name and the rules.
Southern Utah is my home turf. Holladay is not, so these pages are researched rather than lived: checked against city, county and venue sources, and dated so you can see how fresh they are. For the on-the-ground work here I lean on a Salt Lake County partner agent.
Start here
The canyon round the back of the mountain in the window.
Neffs Canyon cuts east into the north side of the Mount Olympus massif, which means it is behind the peak Holladay looks at rather than in front of it. From the valley you barely see it. From the trailhead you are in it within a hundred yards. It is the nearest canyon to a Holladay address that is not protected drinking water, and that one administrative fact is why it appears on this companion at all.
The trailhead is a small lot at the top of White Way, reached by driving up through a residential street above Olympus Cove. Being precise about where that is matters: Olympus Cove incorporated into Millcreek in 2016, so the lot sits just over Holladay's northern boundary rather than inside it. For anybody living on the Holladay bench it is still a ten minute drive and the obvious weekday walk, which is a more useful fact than the city line.
What you get for that drive is a Forest Service trail with no fee, no facility, no water and no crowd worth the name. The agency publishes Neffs Canyon Trail 456 at about 4.44 miles with roughly 1,821 feet of elevation gain, notes leashed pets as permitted, and states plainly that there is no motorised use and that the route is not suitable for bikes or horses. It climbs through oak and maple into open ground under the ridge that separates this drainage from Mill Creek Canyon.
Neffs in numbers
4.44 mi
the trail, per the Forest Service
1,821 ft
of gain on the same listing
1,163 ft
how deep the cave goes
1949
the year two brothers found it
Where the name comes from
A flour mill and the man who would not price it.
The Neff name attached to this drainage belongs to a family that arrived with the 1847 companies. John Neff bought mill burrs from Brigham Young at Winter Quarters, carried them across, and had a flour mill running on the creek in the Mill Creek area by March 1848. It was the first mill in the valley to produce refined flour, which in a settlement's second winter is not a commercial detail but a survival one.
The story that survived about him is a pricing story. Emigrants heading on to California offered a dollar a pound for flour, and the account repeated on the pioneer marker for the site is that he refused it, sold to those in need at six cents a pound, and frequently gave it away to people who could not pay at all. Whether that is complete or burnished is beyond what a page like this can settle; it is presented here as the account on the record rather than as verified conduct.
Sources differ on which Neff the canyon itself is named for. Some attribute it to John, some to his son Franklin. Both are defensible from the published material, and there is no benefit in this page picking one and stating it as settled. The family is the answer; the individual is genuinely uncertain, and anybody who tells you otherwise has read one source rather than three.
The valley's first refined flour came off a wheel on the creek below this canyon, in March 1848.
The thing under the canyon
Eleven hundred feet straight down, behind a locked gate.
This is the most remarkable fact about a drainage that most of the valley has never walked, and it is also the one that most needs stating plainly, because it is not an invitation.
Neffs Cave sits in this canyon on the north side of Mount Olympus. Two teenage brothers found the entrance in 1949 while out walking. Caving teams returned through the 1950s, and in 1956 a party reached the bottom of the main passage and computed a vertical depth of 1,186 feet, a figure later revised to 1,163. That makes it the second deepest cave in Utah and, at various points in the published rankings, somewhere around the fifteenth deepest in North America.
It is also a genuinely dangerous piece of ground, and the Forest Service closed it to the public on safety grounds many years ago and gated the entrance. Access since then has been restricted, granted only through the agency and in practice coordinated with the local grotto of the national caving organisation, which holds the survey knowledge and the rescue capability. This is not a permit that a visitor arranges for a Saturday. It is a controlled entry into a technical vertical system.
The reason to know about it anyway is that it reframes the drainage. A canyon most valley residents drive past without noticing has, underneath it, one of the deepest surveyed shafts on the continent, found by accident by two boys before anybody had any idea what was down there. Walk the trail knowing that and the ground reads differently, which is the whole point of a local page rather than a trail listing.
Do not go looking for the entrance. The gate exists because the cave killed people before it went in, and because a rescue from a vertical system of that depth is an operation rather than a call out. The Forest Service has kept it closed for decades and has not softened on it. Enjoy the canyon on the surface, treat the cave as a piece of local history rather than an objective, and route any genuine caving interest through the agency and the grotto rather than through a walking forum.
The walk, and the rule that makes it useful
Outside the watershed, which changes what you can bring.
| This drainage | The canyons fifteen minutes south | |
|---|---|---|
| Water status | Not inside the protected drinking water watershed | Protected watershed supplying a large share of the valley |
| Dogs | Leashed pets permitted, per the Forest Service listing for the trail | Prohibited outright, including a dog that stays in the vehicle |
| Access | A footpath from a small residential trailhead | State highways with resorts, lodging and winter management on them |
| Facilities | None at all. No water, no toilet, no bin | Resort infrastructure, paid parking systems and services |
| Crowd | Modest, and mostly people who live within a few miles | Regional, national and at times international |
The left column is why a bench household with a dog ends up walking here on a Tuesday evening rather than driving somewhere more famous. The right column is the reason it stays quiet.
What the trail actually does
From the lot the path climbs east straight away, working up through scrub oak and maple on the shaded lower canyon, then opening out into meadow ground below the ridge. The Forest Service figure of about 4.44 miles is the trail rather than the outing, so a full there and back is a substantial half day. Most people turn round at some natural point in the meadows, which makes this an unusually flexible walk: there is no single destination that defines whether you did it properly.
The parking is the etiquette, and the etiquette is the access
You reach this trailhead through a residential neighbourhood, and the lot at the top is small. When it fills, the temptation is to leave the car on the street below. Do not. Trailhead parking restrictions on this side of the valley have tightened in exactly the places where that habit took hold, and a quiet neighbourhood trailhead is precisely the kind that gets restricted first. If the lot is full, drive to Heughs or to the Olympus trailhead instead.
Season, and what the canyon holds
The lower canyon is walkable from spring through autumn and turns into mud and old snow either side of that. There is no water on the route, the lower slopes are warm dry rocky ground where rattlesnakes are entirely at home, and mobile coverage drops off inside the drainage. None of that makes it a serious undertaking; it makes it a walk that rewards boots, a bottle and telling somebody where you went.
What this page is not about
- Mill Creek Canyon. That is a separate and much larger canyon further north with a road up it, its own fee and its own dog system, and it belongs to the Millcreek companion rather than to this one.
- Big and Little Cottonwood. Four resorts on two state highways in a protected watershed, written once at region level along with the winter rules for driving them.
- The Bonneville Shoreline Trail. The bench through route, its gaps and the Parley's Canyon break run across six cities and are a county subject, not a Holladay one.
- Caving as an activity. This page names a closed cave as local history. It is not a guide to entering anything, and the agency and the grotto are the only route to that conversation.
Keep reading
More of Holladay on The Local.
Things to do
The top 6, ranked
A September arts night, a 9,026 foot summit, a dog legal canyon and a creekside park.
Read the guideThe centre
Holladay Village
The plaza, the park, the arts calendar, and the city hall that moved out for two years.
Read the guideThe peak
Mount Olympus
The wall in the east window: 4,158 feet of gain, a scramble, and a waterfall next door.
Read the guideThe address
Living at the mouths
What living at the top of the canyon roads involves, from the creek to the building site.
Read the guideMoving here
An east bench address
Bench snow, old trees, private lanes, and a city with a village instead of a downtown.
Read the guideThe companion
Holladay, the whole picture
The village, the peak, both canyon mouths, the dog canyon and the bench address, in one place.
Read the pageQuick answers
Neffs Canyon, answered.
Yes, on a lead. The Forest Service listing for Neffs Canyon Trail 456 states that leashed pets are permitted, and the reason is that this drainage is not inside the protected drinking water watershed. Dogs must also be under control at the trailhead and in the car park. This is not one of the canyons that runs an odd and even off leash system, and it is the opposite of Big and Little Cottonwood, where dogs are prohibited outright.
At the top of White Way, reached through the residential streets above Olympus Cove on the east side of the valley. Olympus Cove incorporated into Millcreek in 2016, so the lot sits just over Holladay's northern boundary rather than inside the city, though for most Holladay addresses it is still about a ten minute drive. The lot is small, there are no facilities, and there is no public parking in the neighbourhood below it.
The Forest Service publishes Neffs Canyon Trail 456 at about 4.44 miles with roughly 1,821 feet of elevation gain, and notes no motorised use and that the route is not suitable for bikes or horses. That distance is the trail rather than the round trip. The path climbs east through scrub oak and maple on the shaded lower canyon and opens into meadow ground under the ridge, with no single destination that defines whether you finished it.
1,163 feet, revised down from a computed 1,186 feet when a party first reached the bottom of the main passage in 1956. That makes it the second deepest cave in Utah and places it around fifteenth deepest in North America in published rankings. The entrance was found in 1949 by two teenage brothers out walking in the canyon, on the north side of Mount Olympus, and systematic exploration followed through the 1950s.
No, not as a visitor. The Forest Service closed the cave to the public on safety grounds many years ago and gated the entrance, and access since then has been tightly restricted through the agency in coordination with the local grotto of the national caving organisation. It is a technical vertical system where a rescue would be a major operation. Treat it as a piece of local history rather than as an objective, and do not go looking for the entrance.
The Neff family, who arrived with the 1847 pioneer companies. John Neff bought mill burrs from Brigham Young at Winter Quarters and had a flour mill running on the creek in the Mill Creek area by March 1848, the first in the valley to produce refined flour. Published sources differ on whether the canyon carries John's name or that of his son Franklin, and there is no settled answer, so the family rather than the individual is the honest attribution.
No, and confusing them is easy because they share a mountain and a family name. Mill Creek Canyon is a much larger canyon further north with a paved road up it, an entrance fee and a well known odd and even dog system. Neffs Canyon has no road, no fee and no facilities at all: it is a small trailhead at the end of a residential street opening onto a footpath, and it cuts into the north side of the Mount Olympus massif.
It is friendlier than the Mount Olympus trail on the front of the same mountain, mostly because there is no scramble and no single summit to feel obliged to reach. The lower canyon is shaded and the gradient is honest rather than brutal, and turning round in the meadows is a complete outing. What it is not is a stroll: there is no water, no toilet, no bin and no phone coverage inside the drainage, so go equipped for a real walk.
Spring through autumn, with early autumn probably the best of it: cool air, colour in the oak and maple, and firm ground. Either side of that the lower canyon turns to mud and old snow. Summer works if you go early, because the lower slopes are warm dry rocky ground where rattlesnakes are perfectly at home and there is no water anywhere on the route. Mobile coverage drops off once you are properly in the drainage.
A canyon behind the houses is what people actually buy on this bench.
The listing will sell you the ski resorts. What a household here uses on a Tuesday evening is a trailhead ten minutes away where the dog is welcome and the lot has six cars in it. That distinction is worth having before you choose a street. Tell me what matters to you and I will put you with a Salt Lake County partner agent who can sort the ground work.
Referral disclosure. Outside Southern Utah, I connect home sellers and buyers with partner agents I trust in their area. If you choose to work with an agent I refer, that agent's brokerage pays my brokerage (Real Broker, LLC) a referral fee. The fee comes out of the agent's compensation; it is not an added cost to you. You are always free to choose any agent you wish, and using a referred agent is never required.