The following words and terms, when used in these sections, shall have the following meanings, unless the context clearly indicates otherwise.(1) Lake Lyndon B. Johnson Water-Quality Area--Those portions of the Lake Lyndon B. Johnson Watershed within ten stream miles of the pool level of Lake Lyndon B. Johnson (825 feet, mean sea level).(2) Lake Lyndon B. Johnson Watershed--Lake Lyndon B. Johnson and its tributaries located between Alvin Wirtz Dam and Roy Inks Dam.(3) Lake Marble Falls Water Quality Area--Those portions of the Lake Marble Falls Watershed within 10 stream miles of the pool elevation of Lake Marble Falls (738 feet, mean sea level).(4) Lake Marble Falls Watershed--Lake Marble Falls and its tributaries located between Max Starcke Dam and Alvin Wirtz Dam.