US lakes & pondsUS lakes & pondsSurface area: The USGS National Hydrography Dataset outline (NHD Permanent ID 136893446).
The closest airport with scheduled passenger flights to Twentymile Reservoir, plus larger airports within about 150 miles:
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Airports with scheduled airline service from OurAirports (large and medium airports); larger airports are FAA large, medium and small hubs by FAA CY2025 enplanements ("major airport" = FAA large hub). Distances are straight-line from the lake's center, not driving distance; road routes are longer.
The red circle marks Twentymile Reservoir.
Towns and counties: U.S. Census Bureau boundaries overlaid on the USGS lake outline (Wyoming: incorporated places touching the lake, otherwise the nearest one).
Official WGFD pages. Rules and fees change; check before you go.
Built only from the data on this page: official access lists, OpenStreetMap beaches and trails, campground listings, state and USGS invasive-species records. We don't rate crowds or water quality.
No public access sites are listed for this water in the OpenStreetMap boat ramps (no statewide agency ramp layer used) data.
Shoreline: USGS National Hydrography Dataset (NHD Waterbody, Permanent ID 136893446), public domain. State outline: U.S. Census Bureau TIGERweb. Points: OpenStreetMap boat ramps (no statewide agency ramp layer used). Interactive map: Leaflet with © OpenStreetMap contributors. Not for navigation.
We found 2 campgrounds and RV parks within 15 miles of Twentymile Reservoir. Distances are straight-line from the nearest point on the shoreline, so driving distance is longer.
All campgrounds & RV parks in Wyoming
Green tent icons on the lake map mark campgrounds near the shore, and the interactive map shows the closest 12. Amenities are listed only where a source records them; call or check the campground's website before you go, since seasons and rates change every year.
Campground data: OpenStreetMap contributors (ODbL). Pulled Oct 12, 2026.
Live from the National Weather Service API for the lake's coordinates (42.0894, -105.7478). The nearest station may be several miles away. NWS forecast for Twentymile Reservoir. No live water-temperature sensor is shown because we haven't found a public one for this lake.
Based on solunar theory, an estimate. Major periods (about 2 hours) center on when the moon is directly overhead or underfoot; minor periods (about 1 hour) center on moonrise and moonset. The 0–100 activity score rises during those periods and gets a boost near sunrise and sunset and around the new and full moon. Weather, water temperature and pressure often matter more. Sun and moon times are calculated in your browser from the lake's coordinates with standard astronomy formulas, shown in MT (America/Denver), and accurate to within a few minutes.
Twentymile Reservoir covers about 10 acres in Rock River, Wyoming (Albany County).
Yes. We list 2 campgrounds and RV parks within 15 miles.
Twentymile Reservoir touches Rock River in Albany County, Wyoming.
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Straight-line distance between lake centers. All Wyoming lakes & ponds · All waters in Rock River