Improving Austin Streams: An Implementation Plan for Total Maximum Daily Load Allocations in 4 Austin Watersheds Chris Herrington, PE Manager, Water Resource Evaluation Section
E. coli as a fecal indicator Measure potential for fecal contamination, not actual presence of pathogens Long-term measure of conditions, not an assessment of human risk Contact Recreation Standard set by Texas Commission on Environmental Quality, primary standard is 126 mpn/dl Assessed using geometric mean over 5+ year period
Taylor Slough South (2002) E. coli: 545 mpn/dl Spicewood Trib to Shoal (2002) E. coli: 786 mpn/dl Waller Creek (2004) E. coli: 183 1,015 mpn/dl Walnut Creek (2006) E. coli: 902 mpn/dl
Austin s Options to Address Impairments Option Do nothing Find the problem, fix it, monitor for at least 2 years Change designated use with Use Attainability Analysis Watershed Protection Plan Total Maximum Daily Load (TMDL) Implication for Austin Exposes citywide stormwater MS4 permit to modification, does not protect citizens Distributed sources extremely difficult to find, leaves MS4 permit exposed to modification Will not fix all the problems, leaves MS4 permit exposed to modification Significantly more complicated public process, no guarantee of protection for MS4 permit Removes liability from MS4, voluntarily, changeable, no penalty for failure
TMDL/I-Plan Process TCEQ develops TMDL how much bacteria needs to be reduced Stakeholders develop Implementation Plan who will do what to reduce bacteria developed by coordinating committee facilitated by paid TCEQ contractor 5 year planning period voluntary, no penalty if bacteria are not reduced may be developed in parallel with TMDL
TMDL = ΣWLA + ΣLA + ΣFG + MOS 10,000.0000 1,000.0000 100.0000 Taylor Slough 1403K_1 17294 Flow Duration Flow ft 3 /sec 10.0000 1.0000 0.1000 3 ft3/sec 0.0100 0.0010 Highest 0.0001 Flow High Flow Low Flow 0 % 10 % 20 % 30 % 40 % 50 % 60 % 70 % 80 % 90 % 100 % Historical Flow (SWAT) % of Days the Flow Exceeded Critical Flow 1 ft 3 /sec = 7.7 gal/sec C:\Users\Jneece\Documents\Austin Bacteria\Load Duration Curves\Latest & Greatest\TMDL Taylor Slough 1403K_1 17294 v913.xlsx 11/7/2013
C:\Users\Jneece\Documents\Austin Bacteria\Load Duration Curves\Latest & Greatest\TMDL Taylor Slough 1403K_1 17294 v913.xlsx 11/7/2013 Load Duration Curve 1.E+14 1.E+13 1.E+12 Taylor Slough 1403K_1 17294 Observed Load Load Colonies Per Day (MPN/day) 1.E+11 1.E+10 1.E+09 1.E+08 1.E+07 9.92E+09 1.E+06 Highest 1.E+05 Flow High Flow Low Flow 0 % 10 % 20 % 30 % 40 % 50 % 60 % 70 % 80 % 90 % 100 % % of Days the Flow Exceeded TMDL Allowed Load Wet E. Coli Load Dry E. Coli Load
Sources of Fecal Contamination Domestic pets (dogs, cats) Leaking City wastewater infrastructure Wildlife (deer, bird, racoon, etc.) Humans defecating in creeks Individual homeowner septic tanks
I-Plan Coordinating Committee Austin Water Utility, Watershed Protection Department Austin Environmental Board University of Texas Travis County TxDOT PODER Sierra Club Austin Neighborhood Council Shoal Creek/Pease Park Conservancy Friends of Austin Dog Parks Austin Chamber of Commerce Home Builders Association/Real Estate Council of Austin Developed I-Plan from 02/2013-12/2013: https://www.utexas.edu/law/centers/cppdr/services/tmdl.php
Management Measures Riparian Zone Restoration Wastewater Infrastructure Maintenance Domestic Pet Waste Education Resident Outreach Stormwater Treatment Ʃ TMDL limit = 2.2x10 11 mpn/day Ʃ I-Plan reduction = 3.7x10 16 mpn/day https://www.utexas.edu/law/centers/cppdr/services/tmdl.php
Preserve and Restore Riparian Zones austintexas.gov/blog/grow-zones
TMDL/I-Plan Timeline 08/2010: Austin completes 2 years of verification monitoring 03/2012: Austin asks TCEQ to initiate TMDL 10/2012: TCEQ selects I-Plan contractor 10/2012: First of 2 public meetings to create coordinating committee 02/2013: Coordinating committee starts work on I-Plan 12/2013: I-Plan draft approved 04/2014: TCEQ publishes TMDL, I-Plan for public comment 09/2014: TCEQ adopts TMDL, approves I-Plan
Austin s Environmental Integrity Index 120 sites in 50 watersheds sampled quarterly on biennial basis Water Quality (bacteria, nutrients, solids, physical) Sediment (metals, pesticides, PAH, PCB) Biology (macroinvertebrates, diatoms) Habitat Aesthetics $45,000 in annual analytical costs and 112 person-days in field labor austintexas.gov/department/environmental-integrity-index
Atrazine (ug/l) Individual Action Impacts Creeks Average atrazine in Austin surface water sites and springs 1.00 0.90 0.80 Groundwater Surface water 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
For More Information Chris Herrington, City of Austin Direct: (512) 974-2840 Email: Chris.Herrington@austintexas.gov 24-hour Environmental Hotline (512) 974-2550 austintexas.gov/department/watershed-protection