# Why are Western reservoir levels rising right now? 34.37M af across 20 tracked reservoirs as of Aug 25, 2026. Total storage has fallen 19 straight weeks. _Data through Aug 25, 2026 · source last checked Aug 27, 2026 · page revised Aug 27, 2026_ > Tracked-total storage has fallen 19 consecutive weeks, down 6.81M af (-16.5%) since Apr 13, 2026. 14% of California is in drought (D1-D4) or worse, up 7 points week over week (US Drought Monitor). Lake Mead storage is 20% below its 5-yr median for the date. The system is in the summer-fall drawdown, when irrigation and delivery releases typically exceed inflow. Western reservoir levels are not rising right now. Tracked-total storage has fallen for 19 straight weeks and is down 6.81M af (-16.5%) since Apr 13, 2026. For the current picture, see [Why are Western reservoir levels falling right now?](/why/reservoir-levels-falling). ## The numbers | Period | Current | Prior | Change | | --- | --- | --- | --- | | Week over week | 34.37M af | 34.89M af | -1.5% | | Month over month | 34.37M af | 36.74M af | -6.4% | | Year over year | 34.37M af | 39.13M af | -12.2% | | vs 5-yr median | 34.37M af | 39.13M af | -12.2% | ## What fills western reservoirs Western reservoir levels do not rise because it rained yesterday. The West runs on a snow economy: most of the water that fills these reservoirs falls as mountain snow in winter, sits in the snowpack for months, and arrives as runoff when it melts, so reservoir levels move on a seasonal clock with a handful of structural drivers behind it. The combined daily figure behind that clock is the site's total for [western reservoir levels](/reservoir/tracked-total), and everything below explains what moves it. Snowmelt is the engine. From roughly April through June, melting snowpack turns into streamflow and reservoirs catch it; this is when the tracked system typically gains most of the water it will hold all year. The [snowpack pages](/snowpack) show how much snow-water is banked, and the [streamflow gauges](/streamflow) show the melt actually arriving. The winter storm track fills the bank. A wet winter, and especially the atmospheric-river storms that carry much of the West's annual precipitation in a few events, builds the snowpack that becomes spring runoff. A single big storm can also raise rain-fed reservoirs directly, but the durable gains come from snow that melts later. Reservoir operations shape the curve. Dam operators hold space in winter for flood control and then capture the melt as the flood risk passes, so a strong spring fill is partly a management decision, not just weather. The same storage can rise faster when operators are confident the flood season is over. Reduced releases matter as much as inflow. When irrigation deliveries end in the fall, or when [allocations](/allocation) are set low and less water is called downstream, reservoirs stop losing water even before new supply arrives. Early winter gains are often about releases winding down rather than inflow picking up. Drought recovery is the multi-year version. After a dry stretch, the first wet year mostly refills depleted storage rather than raising deliveries, so levels can climb steeply while the [drought map](/drought) is still shaded. The [basin pages](/basin) show which river systems are doing the recovering. The [tracked-total page](/reservoir/tracked-total) carries the combined daily number this page's direction call is computed from, and the [falling twin of this page](/why/reservoir-levels-falling) covers the same system running in reverse. ## About this data - Source: US Bureau of Reclamation RISE; California reservoirs via CA DWR CDEC - Series: Reservoir storage summed across the tracked set - Geography: The tracked major western reservoirs - Unit: acre-feet - Calculation period: Daily reading - Last observation: Aug 25, 2026 - Update frequency: Daily --- Cite: Combined storage across The Waterline's tracked western reservoirs is 12% below its 5-yr median for the date. The Waterline, data through Aug 25, 2026. https://the-waterline.com/why/reservoir-levels-rising Canonical URL: https://the-waterline.com/why/reservoir-levels-rising