Live reservoirs across the country.
Storage levels, percent-of-normal, and seasonal trends from thousands of U.S. reservoirs and dams — refreshed throughout the day from USGS, USACE, and state water-resource feeds. Built for water managers, anglers, paddlers, and dam operators.
What the reservoirs are holding
How the U.S. reservoir picture is shaping up — storage trends, release patterns, and the wider national context.
The U.S. operates one of the largest reservoir networks in the world — over 90,000 dams with roughly 2,500 major reservoirs on the Colorado, Columbia, Missouri, Tennessee, and dozens of other major river systems. Most of this storage was built mid-century for irrigation, flood control, hydropower, and municipal water supply.
Today, those reservoirs are operating in an environment they were never designed for. Western basins like the Colorado have seen multi-decade declines in storage as snowpack runoff shifts earlier and inflows fall below the assumptions baked into operating rules from the 1960s. Eastern reservoirs on the Tennessee, Ohio, and Cumberland systems generally run closer to seasonal norms but face their own pressure from more frequent extreme-precipitation events that can overwhelm flood-control buffers.
Drill into any state below for current storage levels, percent-of-normal, and seasonal trends. Tap a specific reservoir for its full storage history and downstream gauge readings.
Reservoirs by state
A sample of reservoirs from across the U.S. directory. Drill into any state for a full listing of dams and storage levels.
About the reservoir data
Where does this data come from?
Storage and release data is aggregated from USGS streamgauges below dams, the U.S. Army Corps of Engineers (USACE), the Bureau of Reclamation, and state water-resource agencies. Snoflo joins these feeds with watershed boundaries, weather forecasts, and historical baselines.
What does "percent of normal" mean for a reservoir?
The current storage volume compared to the historical average for the same date. 100% means the reservoir is right at its seasonal average. Below 70% indicates drought-stressed conditions; above 130% can flag elevated flood risk if upstream inflows continue.
How fresh is the data?
Most reservoirs report at least once per day; some USACE projects update every 15 minutes. We re-pull throughout the day. The AI briefing regenerates daily.
Why are some reservoirs missing?
The U.S. has over 90,000 dams, but only a fraction publish near-real-time storage. Snoflo includes every reservoir we can pull a current measurement for. If a reservoir you care about is missing, drop us a note.
Can I get an alert when a reservoir's storage changes?
Yes. Save any reservoir as a favorite in the Snoflo iOS app, set a threshold (e.g. "alert me below 50% capacity"), and you'll get a push the moment it crosses. Free with a Snoflo account.
Is this a substitute for official water-supply guidance?
No. Snoflo is informational. For water-management decisions follow guidance from the operating agency (USACE, Reclamation, or your state water board). Use Snoflo data as one input among several.
Reservoirs by state
Tap any state for a full listing of dams, storage levels, and percent-of-normal in that state.