About GMA-13

Joint Planning

The joint planning process is a result of HB 1763 that was adopted by the Texas State Legislature in 2005. Every five years, groundwater conservation districts within a groundwater management area (GMA) must adopt desired future conditions (DFCs)  for relevant aquifers within the GMA. 

Click on the PDF File below to read about the Major and Minor Aquifers in Groundwater Management Area 13

GMA-13 Aquifers.pdf

Click the PDF File below to read the full 2021 DFC Chart 


Desired Future Conditions 

Desired future conditions are defined in Title 31, Part 10, §356.10 (6) of the Texas Administrative Code as "the desired, quantified condition of groundwater resources (such as water levels, spring flows, or volumes) within a management area at one or more specified future times as defined by participating groundwater conservation districts within a groundwater management area as part of the joint planning process." 

 Not later than May 1, 2021, and every five years thereafter, the districts shall consider groundwater availability models and other data or information for the management area and shall propose for adoption desired future conditions for the relevant aquifers within the management area. Before voting on the proposed desired future conditions of the aquifers under Subsection (d-2), the districts shall consider:

(1)  aquifer uses or conditions within the management area, including conditions that differ substantially from one geographic area to another;

(2)  the water supply needs and water management strategies included in the state water plan;

(3)  hydrological conditions, including for each aquifer in the management area the total estimated recoverable storage as provided by the executive administrator, and the average annual recharge, inflows, and discharge;

(4)  other environmental impacts, including impacts on spring flow and other interactions between groundwater and surface water;

(5)  the impact on subsidence;

(6)  socioeconomic impacts reasonably expected to occur;

(7)  the impact on the interests and rights in private property, including ownership and the rights of management area landowners and their lessees and assigns in groundwater as recognized under Section 36.002;

(8)  the feasibility of achieving the desired future condition; and

(9)  any other information relevant to the specific desired future conditions.

Groundwater Availability Modeling 

Groundwater, along with surface water, is important for maintaining the viability of the state's natural resources, health, and economic development. The projected doubling of the state's population by the year 2060, coupled with the constant threat of drought, makes it imperative that Texas develop effective plans to meet future water needs. Effective planning, however, requires accurate assessments of the availability of water, and assessing the availability of groundwater is often much more difficult than assessing that of surface water.

Groundwater is difficult to observe and measure because it resides below the land surface and responds to rainfall much more slowly than rivers and lakes do. Aquifer systems are complex due to flows into and out of the aquifer, the interaction between surface water and groundwater, and the uncertainty of aquifer properties.

Because of this complexity, computer models are excellent tools for assessing the effect of pumping and droughts on groundwater availability. Groundwater availability modeling is the process of developing and using computer programs to estimate future trends in the amount of water available in an aquifer and is based on hydrogeologic principles, actual aquifer measurements, and stakeholder guidance.