The Tres Palacios River is located in south Central Texas in Wharton and Matagorda Counties. Over the past few years, the Texas Natural Resource Conservation Commission has listed the Tres Palacios River on the Clean Water Act 303d list as an impaired water body for high fecal coliform bacteria and nutrient levels. Occasionally, high bacterial levels in the river, especially after storm events, have resulted in oyster bed closings. The Tres Palacios River watershed includes the river itself, ten tributaries, and the mouth of Tres Palacios Bay. It encompasses an area of approximately 322 square miles and extends from the City of El Campo to the City of Palacios.
Land use is predominantly agricultural, with rice and ranching as the primary land use.
The Tres Palacios River has two distinct uses. The headwaters of the river are used as a drainage way for the City of El Campo's stormwater and municipal wastewater treatment plant discharges. Base flow in this area is intermittent and coincides with rain events and treatment plant discharges. In contrast, the lower portions of the river are used for contact recreation such as swimming, water-skiing and fishing. The river discharges into Tres Palacios Bay, one of the larger secondary bays in Matagorda Bay.