Boating Lake DeSmet
Two public launches, about 3,400 acres to explore and the state rules that keep everyone safe on the water.
Where to launch
| Site | Get there | What is there |
|---|---|---|
| Mikesell-Potts Recreation Area (Johnson County) | I-90 Exit 51, south shore | 2 boat ramps, beach, day-use areas, campground. [Johnson County] |
| Monument Point (Game and Fish) | I-90 Exit 47, east on Shell Creek Rd to Monument Rd | Concrete ramp, dock, outhouse. Open year-round. No camping. [WGFD] |
Docks and shoreline improvements need a county application, and the county publishes its own public use regulations for the reservoir. Read them before you build or tie up anything. [Johnson County]
Aquatic invasive species inspection
- Every boat brought into Wyoming from March 1 to November 30 must be inspected before launching.
- A boat that has been on infested water in the last 30 days needs an inspection any time of year.
- Stop at every open check station, kayaks, canoes and rafts included.
- AIS decal for 2026: motorized $10 resident, $30 nonresident. Non-motorized $5 resident, $15 nonresident. Non-motorized inflatables 10 feet or shorter and paddleboards are exempt from the decal.
- Clean, drain, dry. Pull your drain plug for transport.
[Wyoming Game and Fish, May 2026]
Wyoming rules on the water
- Registration: required for any motorboat, electric trolling motors included.
- Life jackets: a wearable life jacket for every person aboard. Children 12 and under wear one while underway unless inside an enclosed cabin. Required for anyone on a personal watercraft or being towed. Boats 16 feet and longer carry a throwable device.
- No wake: 5 mph or less within 100 feet of a drifting, trolling or anchored boat or a person in the water.
- Diver-down flag: no motorboat may operate within 100 feet of one.
- Operators: 16 and older, or with an adult aboard.
- Personal watercraft: kill-switch lanyard attached.
- Alcohol: 0.08 limit for operating a boat.
[Game and Fish watercraft rules, 2] Rules can change; Game and Fish is the authority.
Water quality
In mid-July 2026, Wyoming DEQ issued a bloom advisory for Lake DeSmet after confirming a harmful cyanobacteria bloom near Mikesell-Potts. On July 24 it reported no toxins detected, and the lake stayed open for swimming and boating. DEQ's guidance: avoid scums, keep kids and pets away from them, rinse off after contact. [Wyoming DEQ, 2] Current status: WyoHCBs.org.
Paddle, sail, dive
The county lists swimming and boating at the lake. [Johnson County] Sailboats, kayaks and paddleboards use it too. Paddleboards and kayaks follow the life jacket rule. [WGFD] Mornings are usually the calmest time to paddle; stay near shore in a small craft.
Divers use Monument Point, where there is a sunken 20-foot boat offshore and two dive platforms. Divers report red scoria near shore, then weeds and a silty bottom. [PADI dive notes] Fly a diver-down flag; motorboats must stay 100 feet away from it. [WGFD]
FAQ
Do I need a boat inspection to launch at Lake DeSmet?
If your boat is coming into Wyoming between March 1 and November 30, yes, before it launches. Any boat that was on infested water in the last 30 days needs one year-round. Kayaks and rafts must stop at open check stations too.
How much is the Wyoming AIS decal?
For 2026: motorized boats $10 resident, $30 nonresident; non-motorized $5 resident, $15 nonresident. Paddleboards and inflatables 10 feet or shorter are exempt from the decal but still need inspection coming from out of state.
Can you swim in Lake DeSmet?
Yes. The county lists swimming and a beach area on the south side. In summer, check WyoHCBs.org for algae advisories first.
Is there scuba diving at Lake DeSmet?
Yes. Monument Point is the easiest entry, with a sunken 20-foot boat offshore. Divers report red scoria near shore, then weeds and silt. Motorboats must stay at least 100 feet from a diver-down flag.
The lake, four times a year
Ice-on and ice-off notes, what Game and Fish is saying about the fishery, events worth the drive and new places to stay. One email a season.