HYDRO20111 - Laserfiche WebLink

Home Browse Search

GiiI DANCE FOR REVIEW .=.ND APPROVAL/DI S.IP PROVAL OF .APPLICAT TONS TO DISCHARGE URBAN STORM WATER DRAINAGE INTO EXISTING RECLAftATION DELIVERY AND DRAINAGE FACiiITIES HAC2CGROUND Surface runoff from urbanization of lands surrounding Reclamation's projects is changing the character of Reclamation's delivery and drainage facilities. In many areas, lands surrounding Reclamation projects have already been converted, or are rapidly being converted, from agricultural to urban environments. Most Reclamation facilities were designed to handle 25-year frequency storm runoff from agricultural and undeveloped natural lands. Urban runoff, especially from paved surfaces, may easily exceed these limits, causing several problems: 1. High Peak Flows: The impervious surfaces encountered in urbanized watersheds cause more frequent runoff events and higher peak flows than have historically resulted from agricultural lands. Reclamation's facilities, especially earthen drains, were not designed to handle the higher quantities and velocities of water experienced during urban runoff events. 2. Deterioration of Water Quality: Water quality is a major concern to Reclamation. Urban runoff commonly contains oils and grease from city streets, nutrients from lawn fertilizers, industrial runoff, heavy metals, and pesticides. As Reclamation drains begin to receive water from sources other than irrigated agriculture, these facilities may lose their current exemption from regulation under the Clean Water Act. Some facilities may be required to meet Federal and/or state water quality standards or be assigned maximum levels of pollutant loading. . 3_ Safety Hazards: Because of steep banks and high flows, Reclamation facilities can pose safety hazards in an urban environment. Some project facilities have already been piped for safety, health, or aesthetic benefits. However, such enclosure is extremely expensive and detrimental to project wetlands and associated habitat. The piping of some drains on the Rio Grande Project in E1 Paso's Lower Valley to alleviate a serious public health hazard is an excellent example of this. Another potion, fencing of facility rights- of-way, is also extremely expensive and may increase Reclamation's liability. 4. Increased Operation and M.a intenance (06M1 Costs: Some urban developers have modified Reclamation drains without Reclamation or district knowledge, leading to decreased capacity and reduced accessibility for maintenance. Drains located in an urban environment frequently cost mote to operate and maintain because of higher flows, restricted access, aesthetic considerations, and the proximity of high-value improvements susceptible to flood and other damage. Reclamation and its agricultural customers should not have to subsidize the increased cost of urban drains. Urban surface runoff entering Reelamation~project drains is attributable to three primary sources: 1. Passive: Hoth natural and artificial drainages existed in project areas before Reclamation facilities were constructed. Additionally, urban development changes project hydrography. Storm runoff will seek out natural and artificial drainages. Urban runoff may end up in our facilities even '~ though it was not discharged directly into them.