The Lake Travis vicinity lies predominantly within a carbonate rock terrane and is the site of ongoing intensive residential development. Such development may impose adverse environmental effects such as upland erosion, rapid infilling of the lake with sediment, and the ultimate lowering of surface- or ground-water quality. Furthermore, inhabitants may be subjected unwittingly to geologic hazards such as flooding or mass wasting.

The Canyon Group (Missourian Series) is a sequence of westward-dipping, genetically related carbonate and terrigenous clastic facies that crop out in a northeast-southwest belt across North-Central Texas. The section includes stratigraphic units between the base of the Palo Pinto Limestone and the top of the Home Creek Limestone.

Nitrogen isotope ratios of ammonium and nitrate ions from soil and water samples can be analyzed reproducibly with an experimental error of approximately +/-1 parts per thousand (ppt). Two isotopic ranges of soil nitrate are found in the soils of southern Runnels County, Texas. Nitrate from the decomposition of animal waste nitrogen has a dN15 of +10 ppt to +22 ppt. The isotopic ratio is controlled by the volatilization of isotopically light ammonia gas during the decomposition of urea in urine.

Change, both natural and man-induced, is a significant and defining element of the Coastal Zone. Man-induced change, by definition, can be controlled if desired. The work of nature, however, is altered and modified with much more difficulty, if at all, and attempts to do so commonly lead to unintended results. Prudent use and adequate management of the Coastal Zone must consider natural changes.