LAKE TRAVIS WATERSHED DATA REPORT March 2019 The preparation of this report was prepared in cooperation with, and financed through, grants from the Texas Commission on Environmental Quality and the U.S. Environmental Protection Agency. TABLE OF CONTENTS INTRODUCTION ............................................................................................................................................... 8 WATERSHED LOCATION AND PHYSICAL DESCRIPTION .................................................................................. 9 Lake Travis Location and Physical Description ........................................................................................... 9 Lake Marble Falls Location and Physical Description ................................................................................. 9 Pedernales River Location and Physical Description .................................................................................. 9 Physiography and Topography (after LCRA, 2000) ................................................................................... 10 Geology ..................................................................................................................................................... 10 Ecoregion and Climate .............................................................................................................................. 10 Land Cover ................................................................................................................................................ 11 Lower Colorado River Authority (LCRA): Colorado River Watch Network (CRWN) ................................. 11 Endangered Species and Conservation Needs ......................................................................................... 12 WATER QUALITY PARAMETERS .................................................................................................................... 15 Water Temperature .................................................................................................................................. 15 Dissolved Oxygen ...................................................................................................................................... 15 Specific Conductivity and Total Dissolved Solids ...................................................................................... 16 pH .............................................................................................................................................................. 16 Secchi Disk and Total Depth ..................................................................................................................... 16 E. coli Bacteria ........................................................................................................................................... 17 Orthophosphate ....................................................................................................................................... 17 Nitrate-Nitrogen ....................................................................................................................................... 17 Texas Surface Water Quality Standards ................................................................................................... 17 DATA ANALYSIS METHODOLOGIES ............................................................................................................... 18 Data Collection .......................................................................................................................................... 18 Processes to Prevent Contamination ................................................................................................... 18 Documentation of Field Sampling Activities ......................................................................................... 18 Data Entry and Quality Assurance ............................................................................................................ 19 Data Entry ............................................................................................................................................. 19 Quality Assurance and Quality Control ................................................................................................ 19 Data Analysis Methods ............................................................................................................................. 20 Standards and Exceedances ................................................................................................................. 20 1 | P a g e Methods of Analysis ............................................................................................................................. 20 LAKE TRAVIS WATERSHED DATA ANALYSIS .................................................................................................. 24 Lake Travis Maps ....................................................................................................................................... 24 Lake Travis Watershed Trends over Time ................................................................................................ 27 Sampling Trends over Time .................................................................................................................. 27 Trend Analysis over Time .......................................................................................................................... 28 Air and Water Temperature ................................................................................................................. 28 Total Dissolved Solids ........................................................................................................................... 29 Dissolved Oxygen .................................................................................................................................. 30 pH .......................................................................................................................................................... 31 E. coli Bacteria ....................................................................................................................................... 32 Nitrate-Nitrogen ................................................................................................................................... 33 Orthophosphate ................................................................................................................................... 34 LAKE TRAVIS WATERSHED SITE BY SITE ANALYSIS........................................................................................ 35 Site 12369 – Pedernales River at Hammett’s Crossing............................................................................. 48 Site Description ..................................................................................................................................... 48 Sampling Information ........................................................................................................................... 48 Air and Water Temperature ................................................................................................................. 49 Total Dissolved Solids ........................................................................................................................... 50 Dissolved Oxygen .................................................................................................................................. 51 pH .......................................................................................................................................................... 52 E. coli ..................................................................................................................................................... 53 Nitrate-Nitrogen ................................................................................................................................... 54 Site 17335 – Heinz Creek in the Westcave Preserve ................................................................................ 55 Site Description ..................................................................................................................................... 55 Sampling Information ........................................................................................................................... 55 Air and Water Temperature ................................................................................................................. 56 Total Dissolved Solids ........................................................................................................................... 57 Dissolved Oxygen .................................................................................................................................. 58 pH .......................................................................................................................................................... 59 E. coli ..................................................................................................................................................... 60 Nitrate-Nitrogen ................................................................................................................................... 61 2 | P a g e Site 80310 – Pedernales River at Buffalo Crossing ................................................................................... 62 Site Description ....................................................................................................................................