What “Full Pool” and “ft MSL” Mean
The two numbers on every lake page, full pool and feet above mean sea level, explained with Lake Travis, plus a glossary of reservoir terms.
Short answer: Full pool is the level a reservoir is designed to hold for water supply. Lake Travis’s full pool is 681.0 ft above mean sea level (msl). Above it, the water is flood storage.
Full pool, in a picture
Not to scale. Water level of Nov 7, 2026 (TWDB): 3.88 ft below full pool, shown as the ochre band on the bank. Lake Travis today →
What “ft msl” means
Every lake level on this site is an elevation: feet above mean sea level, written ft msl. It says how high the water surface sits, not how deep the lake is. That is why a lake in the mountains reads in the thousands — Lake Powell is at 3,538.30 ft, and one near the coast reads under a hundred: Lake Corpus Christi is at 91.11 ft.
To know if a lake is high or low, compare its level with its own full pool, never with another lake.
Percent full
Percent full compares the water stored in the conservation pool today with the storage of that pool when it is at full pool: 1,025,897 ÷ 1,098,044 acre-ft = 93.4% (Lake Travis, Nov 7, 2026).
Water above full pool is flood storage and is not counted, so a reservoir can read 100% and still be rising. Some sources, like the Corps of Engineers gauges, publish the level but not the percent; those lakes show the distance to full pool instead.
Glossary
- Acre-foot
- The volume of water that covers one acre to a depth of one foot: 325,851 gallons. Reservoir storage is counted in acre-feet.
- ft msl
- Feet above mean sea level. The elevation of the water surface, used as the level of a reservoir.
- Full pool
- The top of the conservation pool: the level a reservoir is designed to hold for water supply. Also called normal pool or top of conservation.
- Conservation pool
- The part of a reservoir that stores water for supply, between dead pool and full pool.
- Dead pool
- The level below which water cannot be released through the dam.
- Flood pool
- Space above full pool kept for flood water, which is released downstream later.
- Drawdown
- A planned lowering of the water level, often in fall and winter.
- Guide curve
- The target level an operator follows through the year.
- IGLD 1985
- International Great Lakes Datum of 1985, the reference for Great Lakes levels instead of mean sea level.
- Provisional data
- Recent readings that the agency may still correct after review.
Where this data comes from
Lake Travis data from the Texas Water Development Board (waterdatafortexas.org). Updated every morning.
Lake Levels Daily is an independent site, not affiliated with TWDB, LCRA, USACE, USGS, NOAA, TVA or any lake operator. Check official sources before making safety decisions.