Use of Bacterial Source Tracking in Support of TMDL Implementation Plan at Middle Rio Grande Watershed

Since the late 1970s, high counts of fecal coliform bacteria from human and animal waste, has been a contamination concern in the Middle Rio Grande (MRG). In September 2000, the draft fecal coliform total maximum daily load (TMDL) for MRG watershed was developed and submitted to EPA. After extensive stakeholder inputs and public comments, this TMDL was approved by EPA in May 2002. Given the vast number of sources of fecal coliform bacteria in the watershed, differentiating these sources by species type or category will provide invaluable data that is essential to adequately and economically design and target specific point and nonpoint source management measures to reduce fecal loading throughout the MRG watershed. During the TMDL implementation phase, New Mexico Environment Department (NMED) and local entities have chosen to utilize an innovative technology known as Bacterial Source Tracking (BST) to determine the specific source of fecal contamination throughout the MRG watershed. One of the unique hydrologic features associated with this pathogen TMDL is the special climatic and rainfall patterns influenced by the North American Monsoon System (NAMS), which has direct impact on ambient water quality sampling strategy. A sanitary survey of source regions, as well as information about land use, population density, wastewater and stormwater infrastructure, agricultural practices, and wildlife provides a good basis to assist in identifying the possible sources of fecal pollutants within the MRG study area. In summary, the benefit of using BST in support TMDL implementation is to provide stakeholders with long-term planning tool and serves as implementation plan guide for collaboration among local, tribal, regional, state, and federal organizations and agencies.