Urban Water Management Plan 2015

7.1.4 Climatic Factors Groundwater levels in the Llagas subbasin and the Coyote Valley subarea are highly depended on rainfall levels, which produce fluctuations in water levels during years of high or low rainfall. Inconsistent water levels due to drought have the potential to impact the supply availability for the City. SCVWD, along with the City and other member agencies, have multiple measures in place to minimize the potential supply impact due to drought and other climatic factors on the water supply. These preventative measures are summarized as follows: • Groundwater Recharge System : In order to maintain groundwater levels, SCVWD imports raw water and manages a recharge system. This facility method recharge system managed by SCVWD accounts for a portion of the total recharge in groundwater basins they manage. • Imported Water Connections : SCVWD supplies water for recharge through the State Water Project and the federal Central Valley Project. Drought and other climatic factors may cause the amount of water typically supplied to SCVWD through these imports to be reduced. 7.2 RELIABILITY BY TYPE OF YEAR Law 10631 (c)(1) Describe the reliability of the water supply and vulnerability to seasonal or climatic shortage, to the extent practicable, and provide for each of the following: 7.2.1 Types of Years This section discusses the type of years considered when evaluating water supply reliability, which are summarized on the following page in Table 7-1 . The conditions are as follows: • Average Water Year – The average water year is a year that represents the median runoff levels from precipitation, as well as the same general pattern of runoff. The supply quantities would be similar to historical average supplies. • Single Dry Year – The single dry year is defined as the individual year with the lowest usable water supply. This condition can be derived as the year with the lowest annual supply and is represented by the year 1977. • Multiple Dry Years – Multiple dry years are defined as the three consecutive years with the lowest usable water supply. The multiple dry years are detrimental to the water supply system because of their adverse effect on the levels of local and state-wide reservoirs, as well as groundwater levels. Available supply for these conditions is constituted as the (A) an average water year, (B) a single dry water year (C) multiple dry water years

August 2016

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City of Morgan Hill 2015 Urban Water Management Plan