Published
How close to the water can you build? The county says 75 feet — and starts measuring higher up than you think
There is a published number, and it is bigger than people expect
Waterfront is most of the reason anyone buys here. It is also the thing most likely to shrink a building envelope, because Fremont County sets a 75-foot building setback from its listed waters and a separate 30-foot riparian buffer on top of it.
The figures sit in Table 5.2 of the county's Development Code, headed Minimum Water and Wetland Buffers and Setbacks. They are not a guideline. They are the standard an application is measured against, and they apply to far more water than most buyers assume — including small ponds and wetlands, and creeks that do not have a name on a road sign.
What the table covers
The code sorts water into four categories and then, for three of them, sets the same pair of numbers. That is worth stating plainly, because people expect a sliding scale and there mostly is not one.
| Category | Building setback | Riparian buffer |
|---|---|---|
| Major rivers and streams, and lakes, reservoirs, ponds and wetlands of 5 acres or more — the list names Henry’s Lake, Henry’s Lake Outlet, Island Park Reservoir and the Buffalo River among others | 75 feet | 30 feet |
| Perennial and intermittent streams with a well-defined channel, and lakes, ponds and wetlands under 5 acres | 75 feet | 30 feet |
| All other streams and wetlands, with a poorly defined channel | 75 feet | 30 feet |
| Irrigation canals and ditches | None | 30 feet |
The riparian buffer is measured differently from the setback: the code puts it at 30 feet from the outside edge of areas where riparian vegetation is dominant, not from the water. On a lot with a wide band of willow, that edge can sit a long way back from anything that looks like a bank.
The named creeks, and why the list matters
The second category is the one that catches people, because it is a roll-call of small water. Among the perennial and intermittent streams with a well-defined channel, the code names a long run of creeks in this basin by name:
- Hope Creek, Rock Creek, Ingalls Creek, Duck Creek, Kelly Creek and Timber Creek.
- Targhee Creek, Howard Creek, Tygee Creek, Twin Creek, Jesse Creek and Jones Creek.
- Enget Creek, Stephens Creek, Meadow Creek, Crooked Creek, Moose Creek and Sheridan Creek.
- Willow Creek, Icehouse Creek, Sheep Creek, Blue Creek, Hotel Creek and Yale Creek.
- Elk Creek, Tom’s Creek, Fish Creek, Strong Creek, Rattlesnake Creek, Sand Creek and Black Springs Creek.
If a channel on your ground carries one of those names, the question is settled before anyone argues about whether it counts as a stream.
A seasonal channel running across a corner of a lot is easy to walk past in August. If it is one of those, or if it simply has a well-defined channel, the same 75 feet applies as applies to the reservoir. And the category after it — all other streams and wetlands with a poorly defined channel — is written to catch what is left, at the same figure.
Where the measurement starts
This is the detail that changes a site plan, and it is easy to get wrong by a useful-looking margin.
“The native vegetation buffers and building setbacks shall be measured from a point five feet vertically above the average annual high water mark and running horizontally the required number of feet.”
— Fremont County Development Code, 2011 Edition (Ordinance 2011-04), section 5.11.090. Retrieved 19 August 2026
Not from the water’s edge on the day you walk it. Not from the high water mark either. From a point five feet vertically above the average annual high water mark, and then horizontally. On flat ground beside a reservoir, going five feet up can move the starting point a considerable distance inland before the 75 feet even begins to count. On a steep bank it barely moves at all.
The same section requires the setback line to be fixed by a permanent monument on each lot line running roughly perpendicular to the stream or lake, and at the centre of each lot that borders it. So on a platted waterfront subdivision, this is not something to be estimated on site — it is meant to be monumented.
What this does to a waterfront lot in practice
Put the two rules together on a typical shoreline parcel and the arithmetic gets uncomfortable quickly.
- Find the average annual high water mark, then the point five feet vertically above it. That is your origin, and it is usually further back than the visible bank.
- Measure 75 feet horizontally from there. Nothing goes in front of that line.
- Separately, identify where riparian vegetation stops being dominant, and keep 30 feet back from the outside edge of it.
- Now apply the ordinary road and property line setbacks from the other three sides of the lot.
- What is left is the building envelope. On a narrow lake lot it can be a much smaller rectangle than the acreage suggests.
This is why the water question belongs in diligence rather than in design. A lot that will not hold the cabin you want is a fact available before an offer, and it is the same category of check as confirming the snow load your engineer will design to.
The part that works in your favour
One provision is genuinely useful if you are looking at subdivided or subdividable ground. The code allows the stream corridor native vegetation buffer and the building setback, held either in common for residents only or dedicated to a public agency that accepts maintenance responsibility, to count toward the open space percentage a subdivision has to provide.
In other words, the land the buffer takes away is not simply lost twice. It can do double duty against the separate open space requirement, which on rural ground here is a substantial percentage of gross acreage. That is a design decision worth raising early with whoever is platting.
Questions worth asking before you commit
- Is there any water on or adjacent to the parcel — including a seasonal channel, a pond under five acres, or a wetland — and has anyone actually walked the boundary in spring rather than late summer?
- Where is the average annual high water mark, and has the five-feet-vertical origin been established from it?
- Are the setback monuments already in place on a platted lot, and if not, who is setting them?
- Where does dominant riparian vegetation end, and does that edge sit further back than the 75-foot line?
- Does any part of the parcel fall inside the Floodplain Overlay, which the code routes to a separate chapter of standards?
- If the ground is being subdivided, is the buffer being counted toward the open space requirement or given away twice?
- Does the remaining envelope actually fit the footprint you have in mind, including the eaves and any deck, rather than just the walls?
- Is there an irrigation canal or ditch anywhere on the parcel? It carries no building setback but still carries the 30-foot riparian buffer, which surprises people who assume a ditch is not water.
- Has the septic design been checked against the same envelope, since a drainfield has its own separation distances and competes for the same dry ground?
None of this makes waterfront a bad buy. It is the reason waterfront is worth what it is worth. It simply means the buildable part of a shoreline lot is a smaller and more precisely defined thing than the deed acreage, and that it is knowable before the money moves — the same way the rest of the pre-purchase checks are.
Common questions
How far back from the water does Fremont County require a building to sit?
Table 5.2 of the Development Code sets a 75-foot building setback for major rivers and streams, for lakes, reservoirs, ponds and wetlands of five acres or more, for perennial and intermittent streams with a well-defined channel, for lakes and ponds under five acres, and for all other streams and wetlands with a poorly defined channel. Irrigation canals and ditches carry no building setback.
Is the riparian buffer the same thing as the setback?
No, they are separate and they are measured from different places. The riparian buffer is 30 feet from the outside edge of the area where riparian vegetation is dominant. The building setback is 75 feet measured from a point five feet vertically above the average annual high water mark.
Where exactly does the 75 feet start?
From a point five feet vertically above the average annual high water mark, running horizontally from there. Not from the water's edge on the day you visit, and not from the high water mark itself. On gently sloping ground that vertical five feet can move the origin a long way inland.
Does a small seasonal creek count?
It can. The code lists perennial and intermittent streams with a well-defined channel by name, including many small creeks in this basin, and then adds a catch-all category for all other streams and wetlands with a poorly defined channel. All of them carry the same 75-foot building setback.
What about a pond on the property?
Lakes, reservoirs, ponds and wetlands are covered in both size categories: five acres and over in the first row, under five acres in the second. Both carry a 75-foot building setback and a 30-foot riparian buffer, so a small pond is not exempt by virtue of being small.
Do I have to put in survey monuments?
The code requires the setback line to be located by a permanent monument on each lot line running more or less perpendicular to the stream or lake, and at the centre of each lot bordering it. On a waterfront plat this is meant to be monumented rather than estimated on site.
Does the buffer land count for anything?
Yes. The code allows the stream corridor native vegetation buffer and the building setback, held in common for residents or dedicated to an agency that accepts maintenance, to count as a component of the open space percentage a subdivision must provide.
What if the lot is also in a floodplain?
The code states that applications in the Floodplain Overlay must comply with the standards of its own chapter, which is a separate body of requirements from these buffers. A parcel can be subject to both, and the floodplain question is worth settling at the same time.