Implementation Plan for Five Total Maximum Daily Loads for Bacteria in Four Austin Streams
EXECUTIVE SUMMARY: The Texas Commission on Environmental Quality (TCEQ) is required to regularly identify water bodies in Texas that do not support their designated uses. Human contact recreation impairment due to elevated levels of fecal indicator bacteria is the most common water quality impairment in Texas. The following four Austin creeks (shown in Figure 1) have been identified as having fecal bacteria levels higher than allowed under the contact recreation category of use assigned to them, in all or parts of their reaches: • Walnut Creek, • Spicewood Tributary (also known as Foster Branch) to Shoal Creek, • Waller Creek, and • Taylor Slough South. The Clean Water Act requires the TCEQ to develop a total maximum daily load (TMDL) for these streams because they do not support their designated uses. The TMDLs are the calculation of the maximum amount of fecal bacteria pollution that these water bodies can receive and still safely meet state water quality standards. The City of Austin requested the TCEQ to develop both a TMDL and to initiate an Implementation Plan (I-Plan) process for these four creeks. A Coordination Committee was formed with public input to guide development of the I-Plan simultaneously with the TCEQ’s development of the TMDL. The Coordination Committee established as its goal “to develop and implement strategies to reduce fecal contamination such that the affected watersheds fully meet the contact recreation water quality standard.” This I-Plan recommends five sets of voluntary management measures to reduce nonpoint source fecal bacterial contamination in these four water bodies, relating to: 1. Riparian zone restoration. Natural riparian buffer areas can reduce instream E. coli bacteria concentrations when stormwater runoff is diverted through them prior to discharge into the receiving water. Urbanization has caused a degradation of some of Austin’s riparian buffer zones. The restoration and enhancement of functional riparian buffers is a primary strategy in this I-Plan to reduce E. coli bacteria concentrations in these streams and citywide. ??Figure 1. Map of watersheds in Austin listed as impaired for contact recreation by the TCEQ. 2. Wastewater infrastructure, focusing on: a. failing on-site sewage facilities or systems which do not meet capacity requirements; b. inspection and repair of wastewater collection lines; c. response to sanitary sewer overflows; d. reducing contamination from failing private laterals through inspection initiated by backups, stoppage or overflows, and legal requirements on property owners to ensure repair of private laterals, including a lien program; e. providing public toilets to reduce fecal contamination from human outdoor defecation 3. Domestic pet waste. Uncollected domestic pet waste is a significant contributor to fecal contamination in streams. Public education may be an effective tool at reducing the fecal bacteria contamination from domestic pets. This I-Plan focuses on reducing contamination from dog waste in parks and public areas through education, installation of pet waste collection bag dispensers and educational kiosks, and efforts to educate commercial and nonprofit organizations to encourage distribution of educational materials to their customers. 4. Resident outreach. Positive actions by area residents are essential to improve the quality of Austin streams. The I-Plan educational efforts are designed to let Austin residents, including neighborhood groups, school children, and the homeless, know how they can make a difference. 5. Stormwater treatment. Stormwater runoff is the dominant mechanism by which nonpoint source fecal loads are transported to receiving waters. Management of stormwater to reduce bacteria can be achieved with non-structural best management practices (BMPs) like riparian zone enhancement or preservation, or with structural BMPs like sedimentation/filtration basins. The total TMDL for all watersheds combined is 2.2x1011 MPN/day. In total, the proposed management measures included in this I-Plan are estimated to result in a reduction of E. coli 3.7x1016 MPN/day. Although tracking the progress of the proposed management measures over time in coordination with monitoring the improvement in instream fecal indicator bacteria will be necessary to determine if the I-Plan achieves the stated goal, this I-Plan appears to achieve the load reduction of the TMDL. In addition to these four streams, City of Austin Watershed Protection Department monitoring has identified a wider range of watersheds in Austin that have levels of fecal indicator bacteria above State of Texas long-term standards (Figure 2), but which technically do not come within this TMDL process. The City plans to use appropriate strategies developed in this I-Plan effort for improving all streams in Austin.