About this project
State parks sometimes keep a diorama near the visitor center: a painted relief of the landscape, with a ribbon of blue resin showing how water moves through it, over this divide, into that reservoir, out through a canal to somewhere far away. People stand in front of them longer than they stand at any signboard. Drive across Colorado in a dry year and the reservoirs make the same point with no label at all: a bathtub ring of pale rock where the water normally sits.
This site is that diorama for the whole state, with real numbers that update daily.
Most of Colorado's people live east of the Continental Divide. Most of its water starts on the west side. The Colorado Water Plan puts about 70% of the state's surface water west of the Divide, and about 80% if the Rio Grande basin is counted with the West Slope, which is the figure usually quoted. Close to nine in ten Coloradans live east of it. Tunnels under the Divide close the gap, taking water from the Colorado River's headwaters and delivering it east.
When Denver turns on a tap, some of that water started as snow above Winter Park and rode the Moffat Tunnel under James Peak; some was Blue River water released from Dillon Reservoir through the 23-mile Roberts Tunnel. Fort Collins and the northern Front Range drink Lake Granby water delivered by the Colorado–Big Thompson Project's Adams Tunnel. Pueblo, Colorado Springs and the Arkansas Valley draw on the Fryingpan–Arkansas Project, which moves Fryingpan headwaters under the Divide into Turquoise Lake and Twin Lakes. On the map, those tunnels are the dashed ribbons crossing the dotted line. On the flow view you can watch each city's water blend from its sources.
This is why a dry winter over Winter Park shows up in a Denver watering schedule. The Divide decides where the water falls. The tunnels decide who gets it.
Every reservoir is drawn as a glass of water, wide at the rim and narrow at the base, like the cross-section of a canyon filling up. The size of the glass is its total capacity. The color inside is the water's source: each headwater has its own hue, and blends stay traceable. The level is current storage, filled by area, so a glass that looks half full holds half its capacity, the same way a tapering reservoir stores less water per foot near the bottom. The bone-colored tick is where the level would sit in a normal year. The drought is the gap between the tick and the waterline.
The rivers use the same hues. Each stream carries its headwater's color, and mainstems shade downstream toward the blend of everything they have collected. A small ▼ beside a glass means storage fell over the past week: the reservoir is being drawn down to keep the river below it flowing. Select any reservoir or gage on the flow view and everything off its downstream path dims, so you can follow where that water goes.
Two of the metro area's best-known lakes get a special label. Cherry Creek and Bear Creek are Army Corps of Engineers flood-control reservoirs, not water supply. The pool you sail on is a small permanent one, and most of each dam's capacity is kept empty for a flood. They are on the map because everyone sees them, and because the lake you see is usually not the water you drink.
The water year ran from October 1, 2025 to September 30, 2026. The winter looked survivable on paper: statewide streamflow held between 76% and 79% of the median from November through February, and basin storage ranged from 69% of median in the Gunnison to 116% in the South Platte. Then March turned warm early. Flow jumped to 93% that month as the snow started melting, and by the first of June 91% of the state's SNOTEL snow-measurement sites were bare (NRCS). The melt that should have carried rivers through summer had already come and gone. Statewide streamflow fell to 34% in May and bottomed at 27% in June, then recovered only partway, to 59% in September.
The reservoirs show where it hurt. At the end of September the Gunnison basin stood at 23% of its median storage, down from 83% in March, and the Colorado headwaters at 52%, down from 93% in April. East of the Divide the year ended close to normal: the South Platte at 97%, the Arkansas at 86%, and the Rio Grande at 87%. The San Juan and Dolores ended at 91%. The Yampa and White has no reservoir still reporting telemetry, so its 78% is an estimate.
That end-of-September storage is the carryover water year 2027 starts from. The daily readings on the map now report it, labeled with the new year's day count. Open the timeline and press play to watch water year 2026 happen month by month.
Monthly figures are this site's own derivation: reservoir storage from Colorado DWR's CDSS telemetry against each reservoir's median for the week, and streamflow from the mapped USGS and DWR gages against theirs. Every month, basin by basin, is in the basin history CSV.
All of it is downloadable as plain CSV, with per-row source and as-of columns. None of it is operational data. For decisions, go to the primary sources.
Drought is easy to ignore from a kitchen tap. The water still comes out, the price barely changes, and the shortage is always somewhere upstream. But every tap in Colorado is at the end of a specific thread: a river, a tunnel, a reservoir in the hills. If you can point at your reservoir on a map and say that one, and it's at 54%, the abstraction gets personal.
Start with your ZIP code and follow the thread from your tap to its basin, its reservoirs, and the tunnels that carry it under the Divide. It is a simplified picture, since utilities blend sources and trade shares constantly, but the thread is real. Share it: water.myjimmycloud.com#80302 opens the story on that ZIP's water.