Water Quality Models

To help manage the lower Colorado River watershed more effectively, LCRA has developed water quality computer models for the Highland Lakes.

The Colorado River Environmental Models help evaluate water quality problems and issues, discern trends and predict the impacts of various decisions and actions on the Highland Lakes. The models have undergone a rigorous peer review or an independent assessment to ensure accurate computations and scientifically sound results.

The project focuses on evaluating scenarios (related to the TCEQ’s Discharge Ban for the Highland Lakes, the effectiveness of the Highland Lakes Watershed Ordinance and other potential impacts) and investigating the impacts and sensitivity of water quality in each lake to various potential changes.

The model reports are:

• Phase 2 Lake Travis
• Lake Travis Final Report
• Scenario Report
• Phase 3 – Lake LBJ Final Report (Includes lakes Marble Falls and Inks)
• Lake LBJ Final Report
• Scenario Report
• Final Report charts and graphs
1. CREMS3 FinalReport Figure Chapter 2
2. CREMS3 FinalReport Figure Chapter 3
3. CREMS3 FinalReport Figure Chapter 4 Model Result Graphs
4. CREMS3 FinalReport Figure Chapter 4 Segment Map
5. CREMS3 FinalReport Figure Chapter 4 Lake LBJ Longitudinal/Vertical Segmentation
6. CREMS3 Appendix
• Phase 4 – Lake Buchanan
• Lake Buchanan Final Report
• Scenario​ Report​

Discharge Ban

The discharge ban prohibiting the discharge of wastewater effluent in the Highland Lakes is included in a set of rules adopted in the late 1980s by the Texas Commission on Environmental Quality, or TCEQ. These rules, known officially as the Watershed Protection Rules, are described in Chapter 311 of the Texas Administrative Code, subchapters A, B, E and F.