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August 2016
7-2
City of Morgan Hill
2015 Urban Water Management Plan
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
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
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:
(A) an average water year,
(B) a single dry water year
(C) multiple dry water years