The Colorado River of Texas is the longest river contained entirely within the state, traversing approximately 862 miles from its source in the west to the Gulf Coast. This substantial waterway drains a massive basin of nearly 40,000 square miles and is vital for the state’s economy, agriculture, and population. Its name often causes confusion because it is entirely separate from the larger, more widely known Colorado River that flows through the Western United States, which has its headwaters in Colorado.
The Headwaters
The river’s journey begins in the high plains of West Texas, a region known as the Llano Estacado. The origin point is found in the northeastern corner of Dawson County, near the town of Lamesa. In this arid environment, the river starts in “intermittent draws,” meaning its beginning is often dry or consists only of temporary stream beds.
The initial flow is generally shallow and highly variable, dependent on rainfall across the semi-arid rolling prairie. This upper section often lacks a steady stream until it is significantly reinforced by tributaries much further downstream. Early in its course, the river is primarily a feature of the landscape rather than a continuous, free-flowing body of water.
The Journey Downstream
As the river flows southeastward, it transitions from the dry plains into the rugged terrain of the Texas Hill Country, where its character changes dramatically. This middle portion of the river is defined by a chain of major reservoirs known collectively as the Highland Lakes. These lakes were created by dams constructed by the Lower Colorado River Authority (LCRA) for flood control, hydroelectric power generation, and water storage.
The chain begins with Lake Buchanan, the largest of the reservoirs, and continues through Inks Lake, Lake Lyndon B. Johnson (Lake LBJ), Lake Marble Falls, and Lake Travis. Lake Buchanan and Lake Travis serve as the primary water supply reservoirs for the entire region. The river continues through Austin, the state capital, where it forms Lake Austin and Lady Bird Lake, a popular recreational lake downtown.
Below the Balcones Escarpment near Austin, the river leaves the Hill Country’s canyons and enters the Coastal Plain. Here, it becomes a slow, meandering river that flows across the flat, fertile alluvial bottoms. This segment provides water for extensive agricultural operations, including large rice farms, as it continues its final push toward the coast.
The Gulf Outlet
The Colorado River concludes its long run by emptying into Matagorda Bay, an inlet of the Gulf of Mexico, located in Matagorda County near the town of Matagorda. The river’s historical path to the sea was complicated by a massive log jam that formed a natural delta across the bay.
To improve navigation and manage sediment, the river’s channel was modified in the 20th century to bypass the bay and flow directly into the Gulf. The river’s mouth at the Gulf is a brackish estuary system, representing a biologically important zone where freshwater and saltwater mix, creating a nursery habitat for various marine species.