Subsidence can be reduced, stopped in some cases, when the pumping of groundwater is reduced. However, the conversion from groundwater to alternative sources of water (surface water, reclaimed water, etc.) is not as simple. Many of the cities, industries, and others in Regulatory Areas 1 and 2 (the coastal areas) converted in the 1990s to surface water, at considerable costs. Conversion to alternative supplies is an ongoing process for Regulatory Area 3, with full conversion required to be completed by 2035.
Considerable supplies of surface water are available through the development of Lake Livingston on the Trinity River, Lake Houston and Lake Conroe on the San Jacinto River, and the Brazos River. The HGSD reviews the availability of freshwater resources as part of the science and research program. An alternative water supply assessment is currently underway as part of the Joint Regulatory Plan Review, and will include an assessment of aquifer storage and recovery, brackish groundwater and sea water desalination as alternative water supply options.