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INITIAL STUDY/MITIGATED NEGATIVE DECLARATION FAIRVIEw BRIDGE REPLACEMENT AND STREET IMPROVEMENTS <br />(9TH STREET TO 16TH STREET) PROJECT <br />w <br />MAY 2020 <br />SANTA ANAL CALIFORNIA <br />J" <br />3.10 HYDROLOGY AND WATER QUALITY <br />Less Than <br />Potentially <br />Significant with <br />Less Than <br />Significant <br />Mitigation <br />Significant <br />No <br />Impact <br />Incorporated <br />Impact <br />Impact <br />Would the project: <br />a. Violate any water quality standards or waste discharge <br />requirements or otherwise substantially degrade surface or <br />❑ <br />® <br />❑ <br />❑ <br />groundwater quality? <br />b. Substantially decrease groundwater supplies or interfere <br />substantially with groundwater recharge such that the <br />El <br />El <br />® <br />El <br />may impede sustainable groundwater management <br />of the basin? <br />c. Substantially alter the existing drainage pattern of the site or <br />area, including through the alteration of the course of a <br />❑ <br />® <br />❑ <br />❑ <br />stream or river or through the addition of impervious <br />surfaces, in a manner which would: <br />i. Result in substantial erosion or siltation on- or off -site; <br />❑ <br />® <br />❑ <br />❑ <br />ii. Substantially increase the rate or amount of surface <br />runoff in a manner which would result in flooding on- or <br />❑ <br />® <br />❑ <br />❑ <br />offsite; <br />iii. Create or contribute runoff water which would exceed <br />the capacity of existing or planned stormwater drainage <br />❑ <br />® <br />❑ <br />❑ <br />systems or provide substantial additional sources of <br />polluted runoff; or <br />iv. Impede or redirect flood flows? <br />❑ <br />❑ <br />® <br />❑ <br />d. In flood hazard, tsunami, or seiche zones, risk release of <br />❑ <br />® <br />❑ <br />❑ <br />pollutants due to project inundation? <br />e. Conflict with or obstruct implementation of a water quality <br />❑ <br />® <br />❑ <br />❑ <br />control clan or sustainable eroundwater management Dlan? <br />3.10.1 Existing Setting <br />This section is based on the Water Quality Memorandum24 (Appendix A), Location Hydraulic Study" <br />(Appendix A), and River Hydraulics Analysis26 (Appendix A) for the proposed Project. <br />3.10.1.1 Surface Waters <br />The Project area is within the Santa Ana River Watershed, which is within the jurisdiction of the <br />Santa Ana RWQCB. The Santa Ana RWQCB jurisdiction is approximately 2,800 scl mi in portions of <br />Orange, Riverside, and San Bernardino counties and mostly consists of the 2,650 scl mi Santa Ana <br />River Watershed. Specifically, the Project area is within the Lower Santa Ana River Watershed, which <br />extends from Prado Dam to the Pacific Ocean. <br />24 LSA Associates, Inc. 2019e. Water Quality Memorandum: Fairview Street Improvements from 9th Street to <br />16th Street and Bridge Replacement Project BRLS 5063(184). September 16. <br />25 Civil Works Engineers. 2019a. Location Hydraulic Study. Santa Ana River Bridge at North Fairview Street. <br />State Bridge No. 5063 (184). October. <br />26 Civil Works Engineers. 2019b. River Hydraulics Analysis. Fairview Avenue Widening & Bridge Replacement <br />Santa Ana, CA 91303. October. <br />R:\WKE1702\ISMND\Final ISMND\Fairview Street Bridge Final ISMND.docx (05/26/20) 3-53 <br />