RES 98084 - Laserfiche WebLink

Impact C2:: Salt Loading. Irrigation of the proposed golf course and landscaped areas of the residential development will result in impacts to the salt balance of the localized groundwater basin below the golf course. (Project) Such irrigation may also result in impacts to the salt balance of the Alameda County Water District groundwater basin. (Cumulative) : Mitigation Measure C2: With regard to the project impact, it is recommended that the proposed golf ~? course and landscaping areas of the residential development be irrigated with either imported water containing low levels of TDS, or groundwater from the local basin; as well as reduce water. demand by using drought-tolerant planting materials and low water-need turf species for the golf course. The proposed project would provide a beneficial impact by bringing potable water to the. area to replace the use of groundwater. For the possible cumulative impact, it is recommended that Zone 7 continue its studies and implementation its Salt Management Plan (currently under development). The City of Pleasanton will continue to participate in this regional effort. Findings: For the project level impact, there is a potentially significant cumulative impact of salt loading (increased total dissolved solids (TDS)) in the groundwater in the localized groundwater basin below the golf course which may result from the importation of potable water for the irrigation of the proposed golf course and landscaping of the residential development. Regarding the possible cumulative impact, there is a possibility that irrigation water will leave the basin in surface flow, or reach the Alameda County Water District groundwater table. Rationale for Finding: The groundwater at the proposed Happy Valley site is estimated to have TDS levels of approximately 600mg/l. Water which will be imported for the proposed golf course project and landscaping for the residential development is estimated to have TDS levels of 70 mg/l. While the TDS level of the imported water is significantly less that the existing groundwater, salts would nevertheless be imported into the local groundwater basin below the golf course. Also under consideration is the use of local groundwater to irrigate the proposed golf course. Salts from irrigation could leave the basin in surface water flow and possibly impact the Alameda County Water District groundwater table. See "Statement of Overriding Considerations" for the special benefits of the project.