Excess amounts of sediments can make rivers and streams more turbid and can reduce the volume of water that can be stored behind dams. Some sedimentation and erosion also occurs naturally. However, too little or too much sediment can destroy fragile ecosystems. The TWC views sediments as nonpoint source pollutants only when they exceed naturally occurring levels. The TWC recognizes contaminants transported by sediments as nonpoint source pollutants.
Nitrates are a critical nonpoint source pollution problem, especially in groundwaters.
In rare cases, high nitrate levels can cause death in infants who drink contaminated water. Septic tanks, fertilizers, and animal wastes can.all increase nitrate levels in surface and ground waters. Runoff into surface waters can lead to increased algal growth and eutrophication. Not all nitrate problems are caused by man's activities. Many groundwater systems in Texas have naturally occurring high nitrate levels.