Lexington Reservoir Faqs

FACT SHEET Lexington Resevoir FAQs

What are the reasons Valley Water A spillway is a concrete chute that only levels and storage in the aquifer. Water releases water from Lexington? carries water when a reservoir is full. released into Los Gatos creek also The spillway at Lexington Reservoir, makes its way to the underground Mostly, the water released from like most spillways, has no valve, gate aquifer as it travels down the creek. Lexington through its outlet is for water or other method of flow control. Water This system is an integral component supply. This released water percolates flows through it by gravity when the of Santa Clara Valley’s water supply. into our groundwater basins where it reservoir level exceeds its capacity, Lexington has no direct connection to is later pumped from wells. We also and water “spills” over the spillway. any of our water treatment plants. release water to sustain the habitat downstream. Finally, during the rainy The outlet at Lexington was modified In addition, water released from season, Valley Water operates the from 2007 through 2009. The original the reservoir also helps to keep the reservoir to try to maintain storage pipe, more than 30 years old, had creek flowing for fish, animal and space for a moderate rainfall event begun to buckle, resulting in restricted plant habitat. which will allow for controlled releases releases. The project increased the to the creek. These releases are made amount of water we can release How often does Lexington when it is safe to do so and only once through the outlet pipe from 70 cubic reach capacity? the reservoir is nearing capacity. When feet per second to 410 cubic feet per Lexington Reservoir has reached we make these releases, there’s a second. capacity many times. In recent history, strong probability that the released it was full in 2005, 2006, 2011, 2017 water will be recovered with the What is the water in Lexington and now in 2019. This occurs when upcoming rains. Reservoir used for? the amount of rainfall in the watershed What’s the difference between The water in Lexington Reservoir above Lexington Reservoir is so great is used to replenish groundwater that the amount of water flowing an outlet and a spillway? supplies. Water is captured during the into the reservoir over a period of A dam’s outlet is a pipe that runs rainy season and gradually released time exceeds the amount flowing out under or around the bottom of a dam. to Los Gatos Creek throughout the through the dam’s outlet. An outlet has a valve that can be open year. Downstream, the released water or shut to control how much water is is diverted to a series of groundwater released to the creek downstream of recharge ponds that percolate the the dam. water to increase the groundwater

Lexington Reservoir continued on back → Should we be worried when the rates. All of the revenues collected reservoir capacity is above 100%? through water rates must be used for purposes related to protecting Lenihan Dam, the dam that forms and augmenting our water supplies. Lexington Reservoir, was built with a If the dam were operated for flood spillway that can safely pass a large control, the value of that lost water flow of storm run-off. During an intense would need to be funded from other storm, our reservoir gauge may show revenues. a figure that’s well over 100% of the reservoir capacity, but that excess • Releasing stored water for flood risk water will ultimately flow over the reduction could impact our ability spillway. The spillway at Lexington has to fully exercise our water rights successfully conveyed flows every time license. the reservoir has spilled into it. What’s the history of Lenihan Dam However, areas downstream could and Lexington Reservoir? potentially flood when high flows pass over the spillway into Los Gatos In 1952, on the strength of a $2.5 Creek. If the reservoir is full and a large million bond, the agency that ultimately Lexington Reservoir amount of storm run-off continues became Santa Clara Valley Water to flow into the reservoir, the excess District started and completed the Can Lexington’s water storage be 195-foot high, 1,000-foot thick earthen water has nowhere to go but through kept lower to reduce the risk of the spillway to Los Gatos Creek. These dam and the adjacent reservoir that flows from the reservoir combine with flooding downstream? could store more than 19,000 acre feet other creeks and storm drains providing Given the recently updated information of water. One acre foot of water can water to the creek. If too much water that flood risks in Lower Guadalupe supply two families of five for a year. enters the creek at one time, the high River are higher than previously Both took the name of the small town flows can flood low lying trails and local known, we will continue to do our of Lexington, originally located along areas along the creek. best to manage the water level in Los Gatos Creek. The remnants of the Lexington Reservoir, until a more How did Lexington Reservoir abandoned town were submerged appropriate solution is implemented. beneath 130 feet of water as the new look during the 2017 floods from We are currently making releases from reservoir filled. In 1996, the water Coyote Creek? Lexington with a target of reducing district renamed the dam in honor of the storage level in the reservoir. In the winter of 2016-2017, Lexington Jim Lenihan, its longest serving director Strong storms that produce significant at 37 years. Reservoir reached capacity in mid- inflows to Lexington could result in the January, and continued spilling, reservoir exceeding this target at times off-and-on, through the winter and and potentially spilling. CONTACT US early spring, but no significant flooding For more information, contact occurred downstream. Parts of the Managing a reservoir to provide greater Kurt Arends at (408) 630-2284 or by Los Gatos Creek Trail were flooded flood risk reduction is not a decision email at [email protected] for several weeks, as the trail dips we take lightly. Many important factors Or use our Access Valley Water into the creek bed in some places. At come into play. customer request and information one point, parts of Vasona Park were system at valleywater.org to find flooded. There was no flooding in Lower • If we release large amounts out the latest information on district Guadalupe River, even though there of water to manage flood risks projects or to submit questions, were flows over Lexington’s spillway. downstream, there’s then a risk that there won’t be enough water complaints or compliments directly to meet water supply needs and to a district staff person. provide for fish habitat downstream. This can happen even if we don’t FOLLOW US release water for flood control. @scvwd During the historic drought of 2012- @valleywater 2016, Lexington had too little water to keep Los Gatos Creek flowing @valleywater all the way to its confluence with Guadalupe River. To get eNews, drop an email to: A large tree partially submerged in the • The dam and reservoir were built [email protected] Lexington Reservoir near Los Gatos. and are maintained using water