(a) To detect potential violations of this subchapter in the John Graves Scenic Riverway and the Coke Stevenson Scenic Riverway, the commission, the Brazos River Authority or the Lower Colorado River Authority, as appropriate, and the Parks and Wildlife Department shall coordinate efforts to conduct each calendar year:
(1) visual inspections of the riverways; and
(2) testing of water samples drawn from the Brazos River, the South Llano River, and their respective tributaries.
(b) The visual inspections and the drawing of water samples must be conducted at least once in a winter month and at least once in a summer month. The visual inspections must be conducted both from the surfaces of the John Graves Scenic Riverway and the Coke Stevenson Scenic Riverway and from an aircraft flying over the riverways.