Collaborative TMDL Approaches – Driving Future Success in TMDL Development
Abstract:This case study from Tecolote Creek, in the City and County of San Diego, is used to highlight how cooperative approaches to the development of bacterial TMDLs have proven to be effective for both regulators and dischargers. Tecolote Creek, with its aging infrastructure and highly urbanized land use, is a perfect example of a Southern Californian watershed impacted by bacterial contamination and facing an imminent TMDL. In a proactive move to assess and address bacterial loads in Tecolote, the City of San Diego implemented Phase I of a microbial source tracking study in 2007. The study focused on identifying sources of recent fecal contamination, through Bacteroides analysis, and assessing loads both within the creek and from distinct land uses in the watershed through standard culture-based assessments of fecal indicator bacteria (FIB). The results indicated that, while load allocations could be attributed to key land use activities (such as nurseries, restaurants and residential areas), over half the bacterial load was from unknown sources. These unknown sources were most likely to be natural sources such as wildlife and from the regrowth of bacteria in the water column and the sediments of the creek system itself. The results of this Phase I study were then presented to the San Diego Regional Water Quality Control Board through a collaborative communication approach. A Phase II source identification study was then developed for implementation in 2008. Through early communication regarding policy, science and engineering drivers, it has been possible for the City and San Diego Regional Water Quality Control Board to work together toward the development of a refined bacterial TMDL as well as an acceptable implementation plan which addresses key sources. This case study presents an example of how, by early involvement in the TMDL process, stakeholders and regulators can work together to develop effective TMDLs.
Document Type: Research Article
Publication date: January 1, 2009
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