The Colorado River Watershed is a 40,000 square mile basin, stretching from northwest Texas to the Gulf of Mexico and draining into approximately 600 miles of river.  The Lower Colorado River Authority (LCRA) has jurisdiction over 10 counties within the southeastern portion of the watershed and is authorized to provide water services to all or a portion of 33 counties within the State of Texas.  To control the large variation between floods and droughts, the LCRA constructed a series of six dams and reservoirs, called the Highland Lakes.  These lakes provide drinking water for the growing population of central Texas, as well as supply hydroelectric power to nearby communities.  To protect these water resources, the LCRA initiated the development of mathematical models of the Lower Colorado River system.  This project, referred to as the Colorado River Environmental Models (CREMs) project, has been designed to help diagnose existing water quality issues, discern water quality trends, and predict the consequences of various management decisions and associated actions on the water quality of the Highland Lakes.

In addition to collaborating on the development of the CREMs Master Plan, Anchor QEA is currently leading the modeling of Lake Travis, Lake LBJ, and Lake Marble Falls.  Anchor QEA’s main role in the master plan creation was the selection of the suite of models to be used for the Colorado River system, based on extensive experience with watershed and water quality modeling and a thorough understanding of the system.  The model development portion of CREMs has three phases.  The first two phases focus on Lake Travis (the largest of the Highland Lakes).  Phase 3, which commenced in 2008, focuses on Lakes LBJ, Inks, and Marble Falls.  The final work product of Phases 1 and 2 is a comprehensive, linked watershed and lake water quality modeling tool of the Lake Travis basin that can be applied to investigate basin responses (both lake and watershed) to projected growth and/or proposed water quality management practices.  For Phase 2, Anchor QEA led the analysis of data collected during an enhanced monitoring program for the CREMs project, development of the lake water quality model, and linkage of the watershed and lake models for the basin.  Anchor QEA is responsible for developing watershed and lake models for Phase 3, building on the experience gained and tools and protocols established in Phases 1 and 2.

Anchor QEA’s modeling expertise has provided the LCRA with sound advice and guidance on the development, calibration, and potential application of the models for the CREMs effort.  In addition, our insight to the needs and limitations of modeling has helped us to develop sampling programs aiding the model development.  Anchor QEA also has communicated the technical results of the Phase 2 work through meetings with various stakeholders, including the Texas Commission on Environmental Quality, Texas Parks and Wildlife, and Texas Water Development Board, on behalf of the LCRA.