Upper Highland Lakes Watershed Data Report December 2018 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 ................................................................................................................................................... 6 Watershed Location and Physical Description ............................................................................................. 7 San Saba River .......................................................................................................................................... 7 Llano River ............................................................................................................................................... 7 Upper Llano River .................................................................................................................................... 8 Lake Buchanan .......................................................................................................................................... 8 Inks Lake ................................................................................................................................................... 8 Lake Lyndon B. Johnson .......................................................................................................................... 8 TMDL & Watershed Protection ................................................................................................................ 9 Endangered Species and Conservation Needs ........................................................................................ 10 Water Quality Parameters ........................................................................................................................... 13 Water Temperature ................................................................................................................................. 13 Dissolved Oxygen ................................................................................................................................... 13 Specific Conductivity and Total Dissolved Solids .................................................................................. 14 pH ............................................................................................................................................................ 14 Secchi disk and total depth...................................................................................................................... 14 E. coli Bacteria ........................................................................................................................................ 14 Orthophosphate ....................................................................................................................................... 15 Nitrate-Nitrogen ...................................................................................................................................... 15 Texas Surface Water Quality Standards ................................................................................................. 15 Data Analysis Methodologies ..................................................................................................................... 16 Data Collection ....................................................................................................................................... 16 Processes to Prevent Contamination ................................................................................................... 16 Documentation of Field Sampling Activities ...................................................................................... 16 Data Entry and Quality Assurance .......................................................................................................... 17 Data Entry ........................................................................................................................................... 17 Quality Assurance & Quality Control ................................................................................................. 17 Data Analysis Methods ........................................................................................................................... 18 Standards & Exceedances ................................................................................................................... 18 Methods of Analysis ........................................................................................................................... 18 Upper Highland Lakes Watershed Data Analysis ....................................................................................... 21 Upper Highland Lakes Maps .................................................................................................................. 21 2 | Page Upper Highland Lakes Watershed Trends over Time ............................................................................. 22 Sampling Trends over Time ................................................................................................................ 22 Trend Analysis over Time ...................................................................................................................... 23 Air and water temperature................................................................................................................... 23 Total Dissolved Solids ........................................................................................................................ 24 Dissolved Oxygen ............................................................................................................................... 25 pH ........................................................................................................................................................ 26 E. coli .................................................................................................................................................. 27 Nitrate-Nitrogen .................................................................................................................................. 28 Upper Highland Lakes Watershed Site by Site Analysis ............................................................................ 29 Site 81505 – Lake Buchanan at Cassie’s ................................................................................................ 35 Site Description ................................................................................................................................... 35 Sampling Information ......................................................................................................................... 35 Air and water temperature................................................................................................................... 36 Total Dissolved Solids ........................................................................................................................ 37 Dissolved Oxygen ............................................................................................................................... 38 pH ........................................................................................................................................................ 39 E. coli .................................................................................................................................................. 40 Nitrate Nitrogen .................................................................................................................................. 41 Site 13553 – San Saba River at Risien Park ........................................................................................... 42 Site Description ................................................................................................................................... 42 Sampling Information ......................................................................................................................... 42 Air and water temperature................................................................................................................... 43 Total Dissolved Solids ........................................................................................................................ 44 Dissolved Oxygen ............................................................................................................................... 45 pH ........................................................................................................................................................ 46 E. coli .................................................................................................................................................. 47 Nitrate Nitrogen .................................................................................................................................. 48 Site 80435 – Llano River at Mason County Road (CR) 2389 ................................................................ 49 Site Description ................................................................................................................................... 49 Sampling Information ......................................................................................................................... 49 Air and water temperature..................................................................................................................