Evaluation of Nonpoint Source Controls, an EPA/TNRCC Section 319 Grant Report Volume I

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City of Austin Environmental Resources Management Division

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City of Austin Drainage Utility Department


EXECUTIVE SUMMARY: The City of Austin, Texas has been committed to building a comprehensive program of nonpoint source (NPS) pollution control since 1975. Based in part on the Nationwide Urban Runoff Project (NURP) study (Engineering Science and COA, 1983) recommendations, the City developed a stormwater monitoring and evaluation program specifically targeted at NPS pollution indicators. A variety of Best Management Practices (BMPs) have been monitored and evaluated by the City including wet ponds, filtration ponds, and detention ponds. In 1986, the City passed the Comprehensive Watersheds Ordinance or CWO (COA, 1986a) to control NPS pollution from all developing watersheds. This Ordinance requires a full range of BMPs including impervious cover limitations, buffer zones, protection of critical environmental features, limitation on disturbance of the natural stream, erosion control practices, and structural water quality controls. The City also conducts an ongoing public outreach and pollution prevention effort. However, controlling NPS pollution from urbanized watersheds is particularly difficult. Two primary BMPs used in the developing watersheds, impervious cover limitations and buffer zones, are typically not applicable in watersheds with extensive existing development. Structural BMPs are typically very costly since both construction and land costs are increased by the limited number and size of available sites. The advisory board for the City's NURP study recommended that storm loads from high density commercial areas be quantified and that costs and benefits of various structural control measures be obtained. None of the City's previous NPS activities had addressed these recommendations with respect to retrofitting BMPs in existing high density urban watersheds. Therefore, in 1990, the City of Austin Environmental and Conservation Services Department applied for and obtained a $150,000 EPA Section 319 Nonpoint Source Management Program matching grant. The project included storm water monitoring, evaluation of structural BMPs, and non-structural BMP studies such as public education, citizen monitoring, and technology transfer. It is expected that these 1 BMP projects should improve the quality of stormwater runoff to the City's receiving water bodies in the highly developed watersheds. The objectives of this grant study are to: • Develop a storm water monitoring program for studying structural BMPs. • Implement primary structural BMPs and evaluate the treatment or efficiency and cost effectiveness of such BMPs for urban NPS pollution control. • Establish various non-structural BMP programs as a pilot study for source control of urban NPS pollution. • Present the results and conclusions of this study to various communities as a technology transfer program.


This report has a section on Waller Creek which includes a survey of resident aquatic macrobenthos life, algae, flora, geology and life on Waller Creek.

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