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the Edwards Aquifer have confirmed a general southwest to northeast directional flow of groundwater (Murray, Straud, Hammond, 2007; Schindel et al., 2009). This directional flow is not unlike that of surface streams located south and west of the San Marcos area which encounter the Edwards Aquifer along the Balcones Fault Zone (Smith, Hunt, Schindel, 2005). The 1,300 -acre development of Paso Robles (Carma Developers) just north of Hunter Road/FM 2439 in the southwestern outskirts of San Marcos, Texas (Figure 5), will result in the placement of residential homes and a golf course over the contributing zone, which is responsible for collecting water to replenish the Edwards Aquifer, as well as above segments of the aquifer's crucial recharge zone where water enters the aquifer system and continues to flow in a northeastern pattern (Murray, Straud, Hammond, 2007; Schindel et al., 2009; Smith, Hunt, Schindel, 2005). Although the Paso Robles Best Management Practices state that only organic compounds are to be used for treatment of the associated golf course, there is concern that the construction process and subsequent residential use of lawn chemicals such as herbicides and insecticides will adversely influence the water quality of surrounding areas, particularly down gradient of the Paso Robles site location. Further concern lies with the planned application of effluent, or reclaimed wastewater, from the San Marcos Wastewater Treatment Plant on the golf course for irrigation. A holding pond is to be constructed within the site in which the City of San Marcos's treated effluent will be contained. According to the Paso Robles Best Management Practices, the pond will be lined with native vegetation to act as a buffer and aid in the confinement of the effluent within the pond. The effluent will then be piped throughout the development and used for irrigation of the golf course. The Paso Robles Best Management Practices have identified only three holes of the course to be over a designated boundary for the recharge zone. Drinking water supplied by the City of San Marcos is to be used to irrigate the sections of the course containing these three holes. This thesis project will investigate potential changes in water chemistry as a result of the Paso Robles development and associated golf course by assessing the effects of. (1) irrigating the golf course with effluent, or reclaimed wastewater, (2) applying chemicals, such as those found in insecticides and herbicides, on lawns situated atop the Edwards Aquifer, (3) and the presence of volatile organic compounds and polycyclic aromatic hydrocarbons, which may be a byproduct of the construction process. Additionally, this project will aid in the establishment of a routine water quality monitoring schedule of water pumped from two wells used by the San Marcos National Fish Hatchery and Technology Center, which are located immediately down gradient of the Paso Robles development site. These wells are among those selected to be monitored throughout this research project. Water samples taken from nine wells, inferred to be in hydraulic connection both up gradient and down gradient to the Paso Robles site based on knowledge of the general directional flow of the Edwards Aquifer, will be collected bimonthly for analysis (Figure 6). Additional water samples will be collected following significant rain events of at least two inches. This data will be used to indicate changes in water quality that may occur as a result of an increased recharge rate due to precipitation and runoff. This could in turn increase the potential for groundwater contamination. The City of San Marcos's treated effluent will be analyzed from the onsite holding pond, as well as the City's drinking water that is to be used for irrigation over the three holes that are declared by the Paso Robles Best Management Practices to be built over the Edwards Aquifer recharge zone. Monitoring of the wells will occur prior to and throughout construction. One monitoring well is located within the southern portion of the future Paso Robles location, four monitoring wells are located up gradient, and four are located immediately down gradient of Paso Robles with regards to the -3-