Loading reservoir data
Trinity basin · Region C · North Central
TWDB reading Jul 22, 2026
USGS 08064510 — Halbert Lk nr Corsicana, TX
Extrapolated from the past 60 days
Storage rose over the past 60 days, gaining about 7 acre-feet per day.
A straight-line extrapolation, not a forecast. It assumes the recent rate continues unchanged, ignoring seasonality, rainfall and managed releases — and drawdown normally slows as a reservoir falls. Treat it as a severity signal, not a date.
US Drought Monitor for Navarro County, Jul 14, 2026
Conditions in the county containing the dam. A reservoir is filled by a watershed that often reaches well beyond one county, and releases are managed, so local drought is context rather than an explanation of the level.
How today compares with 27 years of record for this date
At 83%, Halbert Lake is within its normal range for this date, higher than 56% of years on record.
Percentiles pool the ±3 days around today across every year on record, so “normal” means normal for this time of year. Conservation capacity is re-surveyed over time, so percent-full comparisons across decades are close but not exact.
Daily TWDB observations, with the normal range for each date
Normal range for the date (25th–75th percentile)Median year
Past 7 days, typically 15-minute readings. USGS elevations use a published datum that may differ slightly from the TWDB daily value above.
CoCoRaHS observers within 60 km of the dam
Rain measured near the dam, not across the watershed. A reservoir is fed by a catchment that can reach hundreds of kilometres upstream, so heavy local rain does not necessarily mean inflow — and a rising lake often reflects rain far from here. Readings are volunteer observations taken once each morning.