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<br /> <br />r!~:!;:~*"~(~'::.:,~ <br /> <br />- ~ _,_...~~?~;,," -.-._:1 <br />::II ,.~,..;,r'~"'.. <br />~... ' '::','::J'.~:' ",~ <br />~..:._"-,,' . <br /> <br />...... <br /> <br />~,~ <br /> <br />1""1r" <br /> <br /> <br />~~ <br />~ <br /> <br />'l <br />.. ... <br /><< <br /> <br />,,~ <br /> <br />. <br />~ <br /> <br />. '- <br /> <br />Record releases from the <br />inundated Friant Dam 011 <br />the S'an Joaquin River in <br />early /997 and subsequent <br />dmvnst ream levee breaks <br />raised lJuestions aboUl rhe <br />l/uamity and timing (~f <br />dam releases. <br /> <br />8 <br /> <br /> <br />.. <br /> <br />~ <br /> <br />~ <br /> <br />4'- <br /> <br />l~ <br /> <br /> <br />j.$e:~ <br />........' <br /> <br />ii- <br /> <br />^, <br /> <br />- <br />1- <br /> <br />.. <br /> <br />. ,.,., <br /> <br />~ <br />.... <br /> <br />~, <br /> <br />,~ <br />J.... <br /> <br />~ <br /> <br />California's flood control reservoirs provide over <br />5 million acre-feet of seasonally-reserved flood <br />control storage, an amount that would cover the <br />entire state to the depth of abouf one-half inch, In <br />addifion, the state has 6,000 miles of levees, <br /> <br />Most dams and reservoirs provide water for more <br />than one purpose, and these purposes often <br />compete with each another. Water managers must <br />keep enough reservoir storage space available to <br />manage floods during the flood season but store <br />enough water to protect against water shortages <br />during the dry season. As one water manager put <br />it, 'The ideal for flood control is an empty reservoir; <br />for water storage, a full reservoir," Additionally, wafer <br />releases to benetit fish and wildlife have become <br />increasingly important and must be incorporated <br />into operational decisions. Construction and <br />operation of flood control systems damaged the <br />riparian environment. <br /> <br />Water releases from dams augment naturally low or <br />intermittent stream flows and repel salt water <br />intrusion from the ocean in low outflow months. <br />To mitigate the projects adverse impacts to fisher- <br />ies, water is released below some dams to help <br />spawning fish, including threatened and endangered <br />species. Dams and reservoirs also provide recre- <br /> <br />a <br /> <br />.~- ,.1,_ <br />...~ <br />..- <br />'~ <br />, ,.,. <br /> <br />,~. <br /> <br />III <br />\. <br /> <br />ii:l <br />0::1 <br /> <br />" <br /> <br />,'>.~ <br />"Y'" ~.~ <br />" - - - ~ <br />,~.-;J'-'i ; <br />,. .~-_... ,. <br />;,>..:f:;:~7i,',;,:,';",., -,';~ ',' i <br />"JiF - J <br />-", ~ ' , I <br />" <br /> <br />.;r) <br />%' ' <br />IIIlIJ! ' <br /> <br />ational opportunities, including swimming, boating, <br />and fishing where public health and safety allow, <br /> <br />All levels of government - local, state and tederal- <br />have a hand in operating the flood management <br />systems, Many of the larger projects, such as Shasta, <br />Folsom and New Melones dams, which are part of <br />the federal Central Valley Project (CVP), are owned <br />and operated by the Corps and/or the U,S, Bureau <br />of Reclamation (Bureau), Some projects, such as <br />Oroville Dam, are owned and operated by DWR, <br />Other systems, such as most of the dams within <br />Los Angeles County, are owned by local agencies <br />and private entities. <br /> <br />There is no single formula for balancing the com- <br />peting needs of each project. There is tremendous <br />variation in hydraulic conditions, including down- <br />stream channel capacities and terrain. In addition, <br />projects operate within various parameters to achieve <br />certain flood protection levels as well as defined <br />water supply, recreation and hydropower production <br />objectives. Operational decisions at each dam are <br />based on criteria developed by historical storm <br />analyses, computer model simulations, statistical <br />risks and downstream impacts. These criteria are <br />used to determine when and how much water is <br />released from the reservoirs during storms. <br />