You're standing where a town used to be. Monarch was flooded in 1950 when Granby Dam filled this valley; record low water has laid the lakebed bare again.
This tool lays a pre‑flood USGS map over the satellite view, shows where you are, and lets you mark the foundations, road cuts, and timber you find.
Two ways in. The first is one tap. The second gives you full control and works with a map you prepared at home.
Use the 1919 USGS sheet of this valley, which names Monarch, its railroad, and Arapaho Creek. It lands already pinned to the earth and works with no signal.
Bring your own scan from USGS topoView and slide, size, and twist it into place over the satellite by eye. Use this for another edition or a map you prepared at home.
Grab a pre‑1950 topo of this valley from USGS topoView, screenshot the mapped area, and bring it back here. Then slide, size, and twist it into place over the satellite view by eye.
The app needs your location to place the orange dot on the old map, so you can walk to a foundation instead of guessing. Your position stays on this device — it's never sent anywhere.
The compass turns the dot into an arrow showing your heading — handy for lining up a road cut or wall running off into the distance. Optional; the dot works fine without it.
Cell coverage on the lakebed is thin. Download the satellite tiles for the townsite now, while you have signal, and the map keeps working when you don't.
Foundation, road cut, timber, stone line — name what you're standing on. Each find is a survey point.
Press and hold anywhere on the map to add one. These outlive today's low water.