Water Quantity

Texas has a diverse array of rivers, aquifers and other ecosystems-these features maintain Texas' unique natural history while supplying water to meet the needs of people. However, the state's water supply is finite, and already stressed by an expanding population and natural drought cycles.

What does the Texas Water Explorer tell us about Water Quantity?

Modeled River Flow Alteration

When river flows are regularly depleted, both ecological integrity and water security for human populations are diminished. We used the TCEQ Water Availability Models to estimate the level of flow alteration in Texas' rivers and summarize alteration patterns across the state.

Flow Depletion - 14% of the state's rivers and streams have flows regularly depleted by more than 50% from the natural conditions.

Alteration of Natural Flow - Flow in 41% of the state's rivers and streams are regularly outside of a presumptive e-flow standard (+/- 20% of natural flows); 31% are frequently under the standard, 2% are frequently over the standard, and 9% are regularly both above and below the standard.

More Reading

Read Texas Water Explorer analysis methods
Texas Commission on Environmental Quality: Water Availability Models
A Presumptive Standard for Environmental Flow Protection

Water Use by Sector: Past, Current, Future

Texas freshwater supplies a growing population and helps maintain a varied economy. This indicator examines patterns in water use by sector across Texas and summarizes the information for river basins, aquifers and counties.

Water Use by Sector - Irrigation (59%) and municipal (28%) water use account for most of the total water use in Texas. Irrigation accounts for 80% of groundwater use and municipal water use is the largest surface water use sector, accounting for 45%.

Overall, use of water for municipal purposes is increasing and use for irrigation is decreasing; this pattern is most prominent in groundwater.

Municipal is the largest water use sector for eight Texas river basins, while irrigation is the largest use sector for six basins. Manufacturing is also the largest water use sector for six basins, while steam-electric power is the largest for two basins and livestock the largest for one.

More Reading

Read Texas Water Explorer analysis methods
Texas Water Development Board: Water Use Estimates and, Frequently Asked Questions

Reservoir Storage

This indicator examines reservoir storage across Texas river basins and the ability of the reservoir system to buffer against drought.

Reservoir Storage - Of the state's 23 river basins, five (Canadian, Trinity, Colorado, Nueces, and Rio Grande) have sufficient reservoir storage capacity for at least a full year's worth of total average annual flow in the basin.

More Reading

Read Texas Water Explorer analysis methods
Texas Water Development Board: Reservoir Levels and Storage

Groundwater Use Relative to Management Restrictions

To maintain Texas' aquifers, groundwater pumping for human uses must be balanced with the health of the surface and subterranean aquatic ecosystems that aquifers support. This indicator examines the compatibility of current levels of groundwater pumping with the pumping limits set by a state planning process designed to balance all these needs.

Groundwater Management Restrictions - 81 counties in Texas already have total annual groundwater pumping in at least one aquifer that exceeds management targets (2010 Modeled Available Groundwater) set to maintain desired future conditions for Texas aquifers.

More Reading

Read Texas Water Explorer analysis methods
Texas Water Development Board: Groundwater Management Areas