California Reservoirs
iOS Universel / Education
California's water, at a glance.
California Reservoirs shows how full the state's major reservoirs are — as a single statewide reading and reservoir by reservoir — with the historical context that makes the number mean something.
WHAT YOU CAN DO
• See current statewide storage and how it compares to the historical average for this date.
• Track every major reservoir: current fill, its 7-day trend, and a storage history going back years.
• Read each reservoir against its typical range, long-term median, and recent precipitation — so a percentage becomes a story, not just a stat.
• Find the reservoirs that actually supply your area — search by ZIP code, city, or your current location.
• Watch drought conditions ease or deepen over time across the state.
BUILT TO BE READ BY EVERYONE
Accessibility isn't an afterthought. Full VoiceOver support, Dynamic Type, Reduce Motion, a complete dark mode, and color-independent state indicators throughout. Charts include non-visual descriptions, and the interface is designed for high contrast and legibility.
CLEAR ABOUT THE DATA
Every percentage names exactly what it's measured against — "of historical average" or "of capacity" — so you always know what you're looking at. Readings come from the California Data Exchange Center (CDEC) and are updated daily; each one is stamped with the date it's current as of, so the app never claims more recency than the data has.
FREE, AND AD-FREE
California Reservoirs is completely free, with no ads and no subscription. It's supported entirely by optional donations from people who find it useful.
ABOUT
This began as a data visualization project tracking California's drought and grew into an app for anyone who wants to understand the state's water at a glance — residents, growers, planners, journalists, and the simply curious. It's a calm, honest look at one of California's most important numbers.
