Watershed Plans and TMDLs
ADEQ's Water Quality Division recognizes three main types of water quality improvement plans as suitable for influencing the prioritization of nonpoint source funding: ADEQ-approved Clean Water Plans (formerly WIP), Total Maximum Daily Load (TMDL) Reports/Implementation Plans (TIPs), and Arizona NEMO Watershed-Based Plans (NEMO Plans).
Clean Water Plans (formerly Watershed Implementation Plans or WIPs) identify priority projects and strategies to mitigate specific impairments. These Clean Water Plans are watershed-based, holistic documents that are designed to protect and restore a watershed. These plans provide a careful analysis of the sources of water quality problems, their relative contributions to the problems, and alternatives to solve those problems. Watershed-based plans should also deliver proactive measures to protect water bodies. In watersheds where a Total Maximum Daily Load (TMDL) has been developed and approved or is in process of being developed, watershed-based plans must be designed to achieve the load reductions called for. If a TMDL has not been developed, required load reductions must be estimated and included in the plan.
TMDLs identify source categories and load reductions necessary to meet standards. A TMDL is a scientific determination of the maximum amount of a given pollutant that a surface water can assimilate and still meet the water quality standards that protect human health and aquatic life. The Total Maximum Daily Load (TMDL) Program is designed to help an impaired stream or lake meet its water quality standards and support its designated uses, such as protection of aquatic life, drinking water, and fish consumption. Section 303(d) of the Clean Water Act established authority for the TMDL Program and guides states on how to develop these plans for waters that do not meet water quality standards.
NEMO plans are the most general plans looking at a watershed-wide scale. These plans identify entire sub-watersheds that are high-risk for various pollutants. The University of Arizona helped develop the Arizona NEMO program which provides large-scale watershed-based plans to aid in achieving water quality standards and protection goals for each of Arizona's major watersheds. These plans identify areas that are susceptible to water quality problems and pollution, sources that need to be controlled, and management measures that must be implemented to protect or improve water quality.