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1.6 STORMWATER FLOOD CONTROL 1.6.1 The Purpose of Stormwater Flood Control Stormwater flood control refers to managin the discharge of stormwater runoff generated by large, intense rainfall events for the purpose of protecting life and property from flood and drainage hazards by maintaining the capacity of the cit stormwater conveyance system. All development permit applications and land use applications are required to discharge their stormwater runoff into discharge facilities having the capacity to remove the stormwater runoff from the basin without creating a risk of flooding or flood damage to other properties in the basin. Applicants may . discharge their runoff into off-site stormwater facilities that have capacity or retain or detain flows on -site with an approved infiltration facility. Off- -site flow methods include discharge to drainage ways (Including roadside ditches and natural drainages and streams), rivers, and engineered stormwater facilities [including culverts, pipes, channels; or other structures]. On -site infiltration methods include surface infiltration and underground injection system infiltration The appropriate discharge point is site-specific and depends on a number of factors, including sail type, slopes, and availability of public and private infrastructure. UfF site discharge to conveyance facilities under the ownership of Lane County or the junction City Water Control District will require the review and ' approval - from the corresponding agency. 1.6.2 Flood Control Design Methodology The Rational Method flow calculation, using the Flood Control design Storm information and desired level of protection provided in Appendix K must be used when evaluating the capacity of the discharge stormwater facility. When determining the basin area, include all developments in the drainage basin area draining into the facility having tentative or final plan approval at the time of your submitted application. 1.6.3 Off-Site Stbrmwater Facilities Development permit applicants discharging runoff to manmade drainage systems designed to accommodate the runoff generated by the stormwater basin area do not need to provide additional analysis of the system for their proposed development The City of Eugene has developed a flood control strategy for each of the drainage basins within the Urban Growth Boundary and published its findings in the- adopted Stormwater Basin Master Plans The Stormwater Basin Master Plans can be used to determine whether the manmade drainage system to which runoff from the development site will discharge was designed to accommodate runoff generated by the stormwater basin area. Development permit applications discharging to manmade drainage systems not designed to accommodate runoff generated by the basin area and all land use applications must demonstrate the off -site flood control facility has capacity to carry post - construction stormwater runoff as outlined in Section L6.2 above or retain or detain runoff on -site or construct a new flood control facility that has flood control capacity. Stormwater Management Manual 1 -15 Bugene 2014