Every two years, Nevada is required by the Clean Water Act (CWA) to conduct a comprehensive analysis of water quality data associated with Nevada's surface waters to determine whether state surface water quality standards are being met and designated uses are being supported. These reports are submitted to the EPA for approval. Once approved this information is used to guide water resource management decisions.
Past waterbody assessments resulted in two products: the Section 303(d) list and the Section 305(b) report. Section 305(b) reporting often allowed for greater flexibility in regards to data age and quantity whereas, the Section 303(d) lists only reported known beneficial use impairments based on high quality data of sufficient quantity to make confident assessments and decisions. Although the programs overlapped, interpretations and comparisons between the two assessments may have been misleading and not afforded water quality managers the ability to accurately describe the status of a single waterbody or the State’s overall water quality.
For these reasons, EPA has encouraged states to adopt an integrated reporting process. The use of a single report will create consistency in the beneficial use assessments and determinations of whether a waterbody is “impaired” or “supported” for assigned beneficial uses. NDEP adopted the integrated reporting process with the Nevada 2008-10 Water Quality Integrated Report.
Nevada 2008-10 Water Quality Integrated Report (includes EPA overlist)
Nevada 2008-10 Integrated Report Web Map Application (modification currently underway to include EPA overlist)
Assessed waterbody segments have designated beneficial uses and water quality criteria designed to protect those uses. To develop the Integrated Report assessment, the designated beneficial uses for each waterbody segment were evaluated to determine their level of support. A given beneficial use is considered to be fully supported if the associated water quality standards are met. Likewise, a beneficial use is not supported (impaired) if any one of the associated water quality standards are not met. In some instances, insufficient data/information may be available to make a use support evaluation. Based upon these assessments, each waterbody segment was placed in one of the following categories:
Category 1: Fully Supported— All designated uses are supported.
Category 2: Some Uses Attained— Available data and/or information indicate that some of the designated uses are supported; and insufficient or no data are available to determine if the remaining uses are supported.
Category 3: Insufficient Information— There is insufficient available data/information to a make a use support determination for any of the beneficial uses. This includes situations for which no data/information exists.
Category 4: Impaired for One or More Designated Uses, but a TMDL is not Necessary— Available data and/or information indicate that at least one designated use is not being supported, but a TMDL is not needed.
Category 4A: A State developed TMDL has been approved by EPA or a TMDL has been established by EPA for any waterbody segment/parameter combination.
Category 4B: Other required control measures are expected to result in the attainment of an applicable water quality standard in a reasonable period of time.
Category 4C: The non-attainment of any applicable water quality standard for the segment is the result of pollution and is not caused by a pollutant.
Category 5: Not Supported— Available data and/or information indicate that at least one designated use is not being supported, and a TMDL is needed. This category is also known as the 303(d) list.
The Section 303(d) list identifies waterbodies that may need additional work, such as the establishment of Total Maximum Daily Loads (TMDLs), to support the beneificial uses. The TMDL process provides an analytical framework to identify the relative contributions of each pollutant. The TMDL identifies the sources and causes of pollution, e.g., point sources, non-point sources, or a combination of both, and establishes allocations for each source of pollution as needed to attain water quality standards. Section 303(d) list is the basis for targeting water bodies for watershed-based solutions, and the TMDL process provides an organized framework to develop these solutions.
NDEP Contact in regards to this report:
Mr. John Heggeness
Division of Environmental Protection
Bureau of Water Quality Planning
901 South Stewart Street, Suite 3001
Carson City, NV 89701
For news media inquiries:
Public Information Officer
Department of Conservation and Natural Resources
901 South Stewart Street, Suite 1003
Carson City, NV 89701