Reservoir Levels Screensaver
The Reservoir Levels screensaver shows real current storage for eight major Western US reservoirs — Lake Mead, Lake Powell, Shasta, Flaming Gorge, Trinity, New Melones, Navajo and Folsom — as percent-of-capacity gauge bars, read directly from the US Bureau of Reclamation's RISE API. It's free, needs an internet connection, and ESC exits.
Live preview
Press ESC to leave fullscreen. Settings are saved in your browser only.
How the Reservoir Levels screensaver works
Your browser reads each reservoir's daily Storage-af series from Reclamation's key-less, CORS-enabled RISE API, refreshing hourly.
Each bar is the latest storage divided by the reservoir's published full-pool capacity in acre-feet.
A small ◆ marker on each bar shows where that reservoir stood on the same date last year, from the same RISE series.
The eight RISE series IDs were verified against Reclamation's catalog; a reservoir simply drops off the board if its series stops reporting.
Reading reservoir storage in the Colorado basin and beyond
The percentages shown are storage as a share of capacity, and the figures come from the Bureau of Reclamation, the U.S. Department of the Interior bureau that operates many large dams in the arid West. Its RISE service (Reclamation Information Sharing Environment) is an open data system that publishes time series and an API for the water data it holds. Storage is measured in acre-feet, the volume of water that would cover an acre to a depth of one foot, about 325,851 US gallons or 1,233 cubic metres.
A reservoir is a bank account for water, filled by snowmelt and spring runoff and drawn down through summer for farms, cities, power and river flows. Lake Mead and Lake Powell sit on the Colorado River, so their levels are closely watched as a rough gauge of the river system’s health. Others, such as Shasta in California, supply different regional systems.
A full percentage can be misleading in either direction. Many reservoirs are managed to leave flood-control space empty at certain times of year, so a below-capacity reading may be intentional. Capacity can also be revised when surveys are updated, and what counts as full pool depends on the reservoir’s design. Compare each bar with the usual level for the season, not only with one hundred per cent.
A worked example
In July 2026 the board shows Lake Mead around 27% full (about 7.1M acre-feet) with its year-ago marker higher — the lake gave up roughly a million acre-feet in a year — while Trinity Lake sits near 78%. In Multi-view it pairs naturally with other earth and climate boards.
Settings & tips
- Sort by orders the board by total storage or by percent full.
- Percent full uses each reservoir's published full-pool capacity — capacities are fixed constants, the storage is live.
- The year-over-year delta is real RISE data too: green means the reservoir holds more water than a year ago.
Frequently asked questions
- Is this real, current data?
- Yes — daily storage values from the Bureau of Reclamation's RISE API, usually current to within a day or two. The header shows the latest reading date.
- Do I need an API key?
- No. RISE is public, key-less and CORS-enabled, so your browser queries it directly.
- Does it work offline?
- No — it needs an internet connection to reach RISE; offline it shows a short notice.
- Is it free?
- Yes — free, no download, in your browser.
- Why these eight reservoirs?
- They're major Reclamation-operated reservoirs with reliable daily storage series in RISE — including the country's two largest, Mead and Powell. State-run reservoirs like Oroville aren't in RISE, so they're not shown.
- Why do reservoirs not always sit at full?
- Operators often hold space for flood control and release water on a schedule for downstream users and hydropower. The right level depends on the season and the year’s snowpack.
- What is an acre-foot?
- It is the volume of water that would cover one acre to a depth of one foot, about 325,851 US gallons or 1,233 cubic metres. It is a standard unit for reservoir storage in the U.S. West.