Today’s water budget · Lake Travis
Where the water came from and where it went, in acre-feet per day at current rates. Mansfield Dam releases and municipal withdrawals have no public feed, so the residual is what the conservation-of-mass equation requires — it is an inference, not a measurement.
- Gauged tributary inflowmeasured+348 af/day
Five USGS gauges, at current rates
- Evaporationmodeled−391 af/day
Climatological estimate over ~17,120 acres
- Storage changeinferred−3,237 af/day
Level trend since midnight, scaled to 24 h
- Releases + withdrawals + ungauged (residual)inferred−3,194 af/day
What conservation of mass requires to balance the books
The residual is equivalent to roughly 1,610 cfs flowing out of the lake — mostly Mansfield Dam releases and municipal intake, plus whatever the gauges upstream didn’t see.
Where it’s going
“River below the dams” is measured at USGS 08158000 (Colorado River at Austin) — a downstream proxy for Highland Lakes releases. The balance leg is whatever the mass-balance residual can’t attribute: municipal intake, ungauged runoff, and estimation error. Legs can overlap conceptually; treat proportions as honest approximation, not gospel.
Gauged flow into the lakes, right now
How this is computed
Inflow converts current streamflow at the five USGS gauges to acre-feet per day (1 cfs ≈ 1.9835 af/day). Evaporation uses long-term monthly averages for the Highland Lakes area over an estimated current surface area — it will switch to TWDB’s daily lake-evaporation model once an API key is configured. Storage change scales today’s level change (vs. midnight, LCRA) to a 24-hour rate using an elevation–area approximation. The residual closes the balance and bundles Mansfield releases, municipal withdrawals, and ungauged runoff — inseparable without data LCRA does not publish.
Early in the day (before ~3 a.m.) the storage trend is withheld to avoid wild extrapolation. All inputs are provisional; treat this page as an honest estimate, not an official accounting.