"Surface water" means the water you can see — rivers and streams, lakes and reservoirs, and the bays and estuaries where rivers meet the Gulf. Texas assesses these waters against the uses they are supposed to support: drinking-water supply, recreation, aquatic life, and the health of fish and shellfish. When a water body cannot meet the standard for one of those uses, it is listed as impaired, and the state must work out why.
The "why" almost always sorts into two broad categories. Understanding the difference is the key to understanding water pollution anywhere in Texas.
Point sources: pollution from a pipe
A point source is pollution that enters the water from a single, identifiable place — most often the end of a pipe. These are the easiest sources to find, to measure, and to regulate, and they are controlled through discharge permits.
- Municipal wastewater. Treated sewage from cities and towns is discharged to rivers and streams under permit. Even well-treated effluent adds nutrients and, when treatment fails, bacteria.
- Industrial discharge. Refineries, chemical plants, food processors and power plants discharge process and cooling water, each under its own permit limits.
- Concentrated animal operations. Large dairies and feedlots can be point sources where waste is collected and released.
Nonpoint sources: pollution from a landscape
The harder problem is nonpoint-source pollution — contamination carried off the land by rain, with no single pipe to point to. It is diffuse, weather-driven, and far more difficult to regulate, and across most of Texas it is now the leading cause of impairment.
- Urban stormwater. Rain running off streets, parking lots and rooftops picks up oil, metals, lawn fertilizer, pet waste and sediment and delivers it, untreated, to the nearest creek.
- Agricultural runoff. Rain moving across cropland and pasture carries soil, fertilizer nutrients, pesticides and animal waste into streams.
- Failing septic systems and direct deposition from wildlife and livestock add bacteria, especially in rural watersheds.
Across Texas, the single most frequent reason a stream is listed as impaired is elevated bacteria — an indicator that water may be unsafe for swimming and wading. Its sources are overwhelmingly nonpoint: stormwater, runoff, failing septic systems and animals.
What the pollution actually is
| Pollutant | Main sources | Why it matters |
|---|---|---|
| Bacteria (E. coli) | Stormwater, septic, animals | Risk to swimmers; most common impairment |
| Nutrients (N, P) | Wastewater, fertilizer, runoff | Algae blooms, low oxygen |
| Sediment | Erosion, construction, cropland | Smothers habitat, clouds water |
| Low dissolved oxygen | Nutrient overload, organic waste | Fish kills, dead zones |
| Metals & toxics | Industry, urban runoff, legacy | Fish-consumption advisories |
From the river to the bay
Because Texas's rivers eventually reach the coast, pollution that begins hundreds of miles inland can end up in the bays and estuaries that anchor the state's fisheries. Excess nutrients are the clearest example: nitrogen and phosphorus washed off distant farmland and city streets feed algae blooms and the low-oxygen "dead zones" that periodically form in Gulf waters. Surface-water quality, in other words, is a single connected system from the Hill Country spring to the shrimp boat.
Why it is hard to fix
Point sources have largely been brought under control through decades of permitting. The remaining challenge is nonpoint pollution, which cannot be solved at a pipe. It requires changing what happens across whole watersheds — how cities manage stormwater, how farms and ranches handle soil and animals, and how fast new development is allowed to pave over land. That makes clean water less a matter of regulating a few facilities than of the cumulative choices made across each of the state's ecological regions.
Sources & further reading
- Texas Commission on Environmental Quality (TCEQ), Texas Integrated Report of Surface Water Quality and the Clean Water Act §303(d) list.
- Texas State Soil and Water Conservation Board, nonpoint-source management program.
- U.S. Environmental Protection Agency, National Water Quality Inventory.
- Texas Water Resources Institute, Texas A&M University.