Eutrophication is one of the top three leading causes of impairments of the nations waters, with demonstrated links between anthropogenic changes in watersheds, increased nutrient loading to coastal waters, harmful algal blooms, hypoxia, and impacts on aquatic food webs. These ecological impacts of eutrophication of coastal areas can have far-reaching consequences, including lowered fishery production, loss or degradation of seagrass/submerged aquatic vegetation (SAV), smothering of benthic organisms, nuisance odors, and impacts on human and marine mammal health. These modifications have significant economic and social costs. In California, the impacts of nutrient loading on estuaries and coastal waters have not been well monitored and no statewide criteria or guidance exist to manage these impacts. Without management actions to reduce anthropogenic nutrient loads and other factors contributing to eutrophication, symptoms are expected to develop or worsen in the majority of systems, due to projected population increases in coastal areas. United States Environmental Protection Agency (USEPA) Region IX and the California State Water Resources Control Board (SWRCB) have previously developed a technical approach and framework for developing numeric nutrient endpoints (NNEs) for California estuaries (USEPA 2007). The stated goal of this effort is to develop a set of numeric endpoints and Total Maximum Daily Load (TMDL) tools that can be used to address impacts from eutrophication through the water quality programs of the SWRCB, Regional Water Quality Control Boards and the regulated community. The USEPA (2007) presented a scientific framework to support the development of numeric endpoints for a suite of biological response indicators (e.g., algal biomass, dissolved oxygen, water clarity, etc.) that are directly linked with estuarine beneficial uses. The framework also highlighted data gaps and research recommendations critical for the development of numeric endpoints and TMDL tools (i.e., watershed loading and estuarine loadresponse models). These tools are critical because they provide the linkage between the numeric endpoints, which are based on biological response indicators, and watershed nutrient loads and other factors controlling eutrophication in estuaries. The purpose of this document is to outline an implementation plan to address these critical data gaps in California estuaries and move forward with NNE and TMDL tool development. The implementation plan proposes a statewide approach to NNE development, with regionalization of numeric endpoints possible if warranted by differences in ecology.