Water budget · Lake Travis

Up or down? Up. TWDB's daily storage for Lake Travis rose 574 acre-feet on Nov 13.

Where the water came from and where it went on Nov 13, the latest day with every figure published. LCRA publishes the dam’s daily release and what flowed in, and TWDB the lake’s daily storage, so all three are measured. The leftover line covers water with no meter (withdrawals, seepage, ungauged creeks) and is inferred from the other lines.

River inflowmeasured
+5,760 af/day≈ +3.61 in/day on the lake
LCRA River Operations Report, daily averages for Nov 13: Starcke Dam release 2,863 cfs + Pedernales 41 cfs
Evaporationmodeled
−186 af/day≈ −0.12 in/day on the lake
Estimate from long-term averages over 19,148 surveyed acres (TWDB)
Dam releasemeasured
−4,897 af/day≈ −3.07 in/day on the lake
LCRA River Operations Report: Mansfield Dam, daily average for Nov 13
Everything else leaving that we can’t meter (withdrawals, seepage)inferred
−103 af/day≈ −0.06 in/day on the lake
What’s left once the other rows and the storage change are counted

=Storage changemeasured
+574 af/day≈ +0.36 in/day on the lake
TWDB Water Data for Texas daily storage, Nov 13 vs. the day before

The lines above add up to the storage change: what the lake gained or lost. Every measured line is a published daily figure for Nov 13; evaporation is a long-term average.

Where it’s going

Mansfield Dam releasemeasured
LCRA, Nov 13
4,897 af/day≈ 2,469 cfs
Evaporationmodeled
estimate from long-term averages
186 af/day≈ 94 cfs
Withdrawals and other unmetered waterinferred
the leftover from the budget above
103 af/day≈ 52 cfs

The release leg is LCRA's reported average release through Mansfield Dam for Nov 13. The withdrawals line is the budget’s leftover: city intakes, ungauged runoff and estimation error. The lines can overlap, so treat the split as approximate.

River flow toward the lake now

Swipe sideways to follow the river to the lake →

SteadyReceding · high water draining downOn the rise · climbing right nowInbound wave · big rise upstreamFlooding · NWS, by river heightNo current readingRising or falling is judged from each gauge’s last 48 hours, scaled to its river. Dot speed follows the flow. NWS flood status comes from river height and outranks direction.

Streamflow at the 4 river gauges (USGS or LCRA, whichever is newer), plus yesterday's average dam releases (LCRA). Labels are gauge readings in cfs. Line width isn’t to scale. The storage line above shows whether Travis is up or down.

How this is computed

Inflow is the water that reached Lake Travis on Nov 13: the daily average release from each dam directly upstream plus each tributary that enters the lake below those dams, as LCRA River Operations Report publishes them, in acre-feet per day (1 cfs ≈ 1.9835 af/day). Rivers that feed the lakes upstream are counted when those dams release them, not before. Evaporation uses long-term monthly averages for the region over today’s lake surface. That surface area is TWDB’s daily survey where published, otherwise estimated from storage. With no storage reading, evaporation isn’t estimated. Inches on the lake divides each volume by that same surface area, so an inch takes less water when the lake is low and narrow than when it’s full and wide. Storage change is TWDB’s daily storage, compared with the day before. The leftover is what it takes to make the lines add up. It lumps together withdrawals and ungauged runoff, which can’t be split without data the operator doesn’t publish.

All inputs are provisional. This page is an estimate, not an official accounting.