1. Urban Hydrology

2. Construction Impacts Disturbed areas allow erosion to occur High concentrations of sediment can impact creeks and ponds Construction General Permit Storm Water Pollution Prevention Plan (SWPPP) must be prepared for project Plan specifies measures to reduce discharge of sediment Disturbed areas allow erosion to occur High concentrations of sediment can impact creeks and ponds Construction General Permit Storm Water Pollution Prevention Plan (SWPPP) must be prepared for project Plan specifies measures to reduce discharge of sediment

3. Silt Fence

4. Hydromulch

5. Control Failure

6. Degradation of Hill Country Streams Green Hole on Lick Creek, west Travis County, Summer 2003 Green Hole on July 27, 2004, after rainfall caused overflow from the West Cypress Hills subdivision detention pond for development construction

7. Degradation of Hill Country Streams (cont.) Dead Mans Hole on Dead Mans Creek, east Hays County, before construction of a small dam in the watershed Dead Mans Hole after construction of the dam

8. Degradation of Hill Country Streams (cont.) Hamilton Pool prior to June 2007 Road cut for land development in Hamilton Creek basin began June, 2007

9. Degradation of Hill Country Streams (cont.) Road cut along Hamilton Creek Hamilton Pool--first rain after road cut construction began

10. Bee Creek Bee Creek near Hwy 71, West Travis County, prior to development in basin Bee Creek, August 2007, immediately after development began in basin

11. Austin Rainfall/Runoff

12. Bear Creek Shoal Creek Fort Branch Boggy Creek Channel Degradation

13. E. Bouldin Creek Walnut Creek Tannehill Branch Shoal Creek Little Walnut Creek More of the Same

14. Shoal Creek

16. Types of Pollution Point Sources –Conventionally industrial or wastewater treatment –Any discharge from a pipe or ditch Non-Point Source –Agriculture Point Sources –Conventionally industrial or wastewater treatment –Any discharge from a pipe or ditch Non-Point Source –Agriculture

17. Constituents in Urban Runoff Bacteria Nutrients Insecticides Herbicides Metals – zinc, copper, lead Hydrocarbons – PAHs Sediment Bacteria Nutrients Insecticides Herbicides Metals – zinc, copper, lead Hydrocarbons – PAHs Sediment

18. Sources of Pollutants Vehicles – Tires, Brake pads, Fluids, Tracking Atmospheric Deposition Fertilizers Pesticides Pets Pavement abrasion Channel Erosion Vehicles – Tires, Brake pads, Fluids, Tracking Atmospheric Deposition Fertilizers Pesticides Pets Pavement abrasion Channel Erosion

19. Buildup of Pollutants

20. First Flush of Pollutants Stenstrom & Kayhanian, 2005

21. Zinc vs. Impervious Cover

22. Copper vs. Impervious Cover

23. TSS vs. Impervious Cover

24. Runoff Concentrations ConstituentAvg. CStandardExceedance Gross Solids???0100% Lead 49  g/L 0.6697% Copper 39  g/L 3.297% Zinc 207  g/L 4152% Fecal C.141540042%

25. Runoff Concentrations ConstituentAvg. C Sediment100 mg/L Nitrate0.93 mg/L TKN2.1 mg/L Total P0.11 mg/L Diss. P1415

26. Sealants reapplied every few years. About 600,000 gallons of sealant are applied annually in Austin. coal-tar- emulsion -sealed asphalt- emulsion -sealed unsealed asphalt or concrete Other Sources of Pollutants

27. Sewer Lines in Creeks – Tannehill Branch

28. Algae blooms March 2, 2002 Barton Creek Wastewater Leak

29. Regulatory Strategies Do nothing Do something (structural) Meet a performance standard Meet water quality standards Do nothing Do something (structural) Meet a performance standard Meet water quality standards

30. Local Requirements Austin – Achieve pollutant reduction comparable to a sand filter system, or “no discharge” of stormwater. LCRA – Reduce TSS, TP, and O&G by 75% TCEQ – Reduce the increase in TSS discharged by 80%. Houston – Do something Austin – Achieve pollutant reduction comparable to a sand filter system, or “no discharge” of stormwater. LCRA – Reduce TSS, TP, and O&G by 75% TCEQ – Reduce the increase in TSS discharged by 80%. Houston – Do something

31. Filter System – Lamar & Loop 360

32. Uniform Distributed Small-scale Controls Maintaining Natural Hydrology Functions