The environmental status of the Guadalupe River in Texas is a complex subject that varies significantly by section and the specific type of pollutant being measured. The "Upper" Guadalupe, located in the Hill Country, is generally considered clean and is a major destination for tubing and fishing; however, it is susceptible to spikes in E. coli bacteria levels following heavy rainfall due to runoff from livestock and septic systems. The "Lower" Guadalupe, which flows through more industrial and urban areas toward the Gulf of Mexico, has historically faced more significant challenges. Certain segments have been listed on the Texas Commission on Environmental Quality (TCEQ) "impaired" list due to elevated levels of mercury in fish tissue and high bacteria counts. In 2026, local conservation groups like the Guadalupe River Park Conservancy are actively monitoring "trash pollution" in urban segments, which remains a visible problem. While the river is safe for recreation most of the time, the city of San Jose's namesake Guadalupe River in California has also faced heavy metal and fecal coliform issues, reminding travelers to check local water quality reports before swimming.