State Water Board Emergency Conservation Regulation

Recognizing persistent yet less severe drought conditions throughout California, on May 18, 2016, the State Water Board adopted an emergency water conservation regulation. The May 2016 regulation that will be in effect from June 2016 through January 2017 requires locally developed conservation standards based upon each water agency’s specific circumstances. It replaces the prior percentage reduction-based water conservation standard with a localized “stress test” approach. These standards require local water agencies to ensure a three-year supply assuming three more dry years like the ones the state experienced from 2012 to 2015.  The City of Morgan Hill has calculated the required conservation standard using the State provided three step process.  The calculations for each step are provided below.  Because the City relies on groundwater for its water supply and that volume of groundwater available to the City is large; the City passed the three dry year stress with a surplus (see tables below).  The State does not require water agencies that demonstrate a surplus to impose an emergency water conservation requirement.  However, the City recognizes water conservation as prudent and the new normal for the State.  The City is therefore self imposing a 20% water conservation requirement.  The 20% reduction is determined by comparing 2016 water usage with usage from 2013 on a monthly basis.
Step 1: Determining Annual Total Potable Water Demand
Units of Measure                                                                AFY
Production, 2013                                                                8,938 afy
Production, 2014                                                                7,495 afy
Annual Potable Water Demand                                      8,216 afy
Note: Production volume per Well Production Records received from City staff.
Step 2: Calculating Total Available Supply
Total Available Supply = Firm City Pumping Capacity x Annual Dry Year Supply Reduction
Estimated City Firm Pumping Capacity = 19,228 afy
Annual Dry Year Supply Reductions
2016          95%
2017          85%
2018          70%
Total Available Supply                                    Annual Dry Year Supply Reduction
2017          18,266 afy                                             95%          
2018          16,344 afy                                             85%
2019          13,459 afy                                             70%
Notes:
1. City firm pumping capacity based on well design capacity.
2. Annual Dry Year Supply Reductions equal to multiple dry year supply reductions consistent with City of Morgan Hill 2015 UWMP.
Step 3: Calculating Self-Certified Supply Conservation Standard
Average Annual Potable Water Demand (from Step 1) 8,216 afy
Potable Water Supply in WY 2019 (from Step 2) 13,459 afy
Supply at the end of FY 2019 (negative no. = surplus) -5,243 afy