Standards for Surface Waters
Water quality standards define water quality goals of a water body by designating uses of the water and by setting criteria necessary to protect the beneficial uses. Beneficial uses include such things as recreation, aquatic life, fisheries, irrigation, and drinking water. Water quality standards for Nevada are contained in the Nevada Administrative Code (NAC), Chapter 445A.118-445A.225.
The NAC contains two types of water quality standards, narrative and numeric. The narrative standards are applicable to all surface waters of the state and consist mostly of statements requiring waters to be "free from" various pollutants including those that are toxic. The numeric standards for conventional pollutants are broken down into two types: class and water body specific. For the class waters, criteria for various pollutants are designed to protect the beneficial uses of classes of water, from A to D; with class A being the highest quality. The water bodies belonging to these classes are named in the regulations.
For major waterbodies in Nevada, site specific numeric standards have been developed. These standards include both criteria designed to protect the beneficial uses and antidegradation requirements. The antidegradation is addressed through the establishment of "requirements to maintain existing higher quality" or RMHQs. RMHQs are set when existing water quality (as
evidenced by the monitoring data) for individual parameters is higher than the criteria necessary to protect the beneficial uses. This system of directly linking antidegradation to water quality standards provides a manageable means for implementing antidegradation through the permit program and other programs. The following waterbodies have site specific standards established:
Numeric standards for toxics for various beneficial uses can be found in NAC 445A.144. Nevada relies on EPA criteria when establishing numeric water quality standards for toxics. EPA criteria are derived from laboratory studies of biological organisms' sensitivity to specific chemicals. In these studies, a variety of fish, benthic macro-invertebrates and zooplankton are exposed to known concentrations of a chemical under varying conditions.
|
Carson River
