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rrritiai Studl'—LID Annexation c) Substantially alter the existing drainage pattern of the site or area, ❑ ❑ including through the alteration of the course of a stream or river, in a manner which would result in substantial erosion or siltation on-or off-site? d) Substantially alter the existing drainage pattern of the site or area, ❑ including through the alteration of the course of a stream or river, or substantially increase the rate or amount of surface runoff in a manner which would result in flooding on-or off-site? e)Create or contribute runoff water which would exceed the capacity ❑ ❑ D E of existing or planned stormwater drainage systems? I)Place housing within a 100-year flood hazard area as mapped on a ❑ ❑ 0 E federal Flood Hazard Boundary or Flood Insurance Rate Map or other flood hazard delineation map? g) Place within a 100-year flood hazard area structures which would ❑ N ❑ El impede or redirect flood flows? h) Expose people or structures to a significant risk of loss, injury or ❑ ❑ N ❑ death involving flooding, including flooding as a result of the failure of a levee or dam? i)Inundation by seiche,tsunami,or mudflow? 11 ❑ 0 Hydrology and water quality issues and impacts were extensively addressed in detail in the River Islands EIR. Hydrology impacts that affect the Project include its location within the 100 year floodplain,the need for specific drainage plans and construction impacts to nearby surface water and manmade lakes. Of these impacts,the issue of biggest concern is that of flood protection. The River Islands project is required to provide at least 100 year level of protection to the project area;the proposed flood control system for the urbanized area of the Stewart Tract, including the LID service area will provide a 200 year level of protection through improvements to Paradise Cut(bench lowering)increasing Paradise Cut flow volumes and capacity, strengthening existing levees,creating high-ground corridors,and constructing back bays at water features. On a regional basis,the proposed River Islands flood protection program could result in increases to flood stage elevations in the surrounding area during severe flood events. However,these increases would be minor and highly infrequent and were therefore, deemed insignificant. Additionally,the Mitigation Monitoring Program adopted by LAFCO when LID was formed in 2002, required equipment and facilities constructed by LID to be placed outside of the 100 year floodplain as possible. This mitigation would be re-ratified with approval of this annexation and satisfied with the implementation of the River Islands program. Constriction of the proposed substation will have minor storm drainage impacts by introducing additional impervious surface. Its construction will require adherence to the City's municipal NPDES permit and meet applicable standards under the West Lathrop Specific Plan. The proposed project does not exacerbate or cause any hydrology or water quality concerns other than those described above that have not be identified,analyzed or mitigated for in the River Islands EIR. As 44