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HomeMy WebLinkAbout5/15/2018 Item 15, Blakely DAVID BLAKELY 861 SKYLINE DRIVE SAN Luls Osisro, CA 93405 PxoNE 805.438-5956 4385956@gmail.com May 10, 2018 RE: Chapter 8 Water and Wastewater Please add my comments to the record for Item 15 on the City Council's May 15, 2018 meeting agenda. It would be helpful if this document included information which would tell the citizens of the City of San Luis Obispo how long the City could provide water to its residents if the recent drought(2011 -2016)would have continued. I heard conflicting information on how long we could last with little to no rain and it would be helpful to have an analytically studied answer to that issue. Provide information that shows the number of years of adequate water the City would have under a continued drought condition. It would also be helpful to have a projection on water availability at the City's three major water sources if we had a series of low rainfall years like we had in 2013 when we only received 3.8 inches of water. This appears to be a worst-case scenario and should be considered in the City's water planning. Provide scenarios of water availability and safe annual yield under multiple scenarios. Cal Poly has a big influence on the City of San Luis Obispo. In Cal Poly's proposed Master Plan, they indicate that they will run out of water before they can complete their plan. This may have an impact on the city's ground water and Whale Rock water supply. I understand the City staff is closely monitoring the Cal Poly Master Plan process. I believe Cal Poly could have a significant impact on the ability of the City to provide water and wastewater services. An acknowledgement of the potential impacts of Cal Poly's growth on the City's water and wastewater system should be considered in this update. Include Cal Poly Master Plan information in water planning for the City The 2017 Water Resources Status Report states that there is a 515.7 AF annual water loss in the system. This water must be used in any calculations of Safe Annual Yield. Chapter 8 Water and Waste Water does not include any of this information nor does it explain how this 515.7 AF are calculated in the systems Safe Annual Yield. This document should show this amount of water loss and explain how it is used in calculations. Water loss from siltation is part of the document but water system water loss is not, and it should be. Include Water Loss data in all calculations Comments: Page 8-9 mentions that for Nacimiento Reservoir"The City has a contractual entitlement to 5,482 AFY of water from the project." But does not discuss climate change, siltation's and droughts which will indirectly provide impacts on this entitlement. I understand the entitlements for water at Lake Nacimiento are different from the city's other reservoirs. Consider the impacts of climate change, drought, and siltation on the reliably of the City's water supply from Lake Nacimiento. 1 Page 8-9 The document deletes some important historical information on groundwater pumping. The problems the City had with the two largest wells is important to recognize. The level of optimism about ground water pumping for the City is over stated. If there is information from a study that is the basis for this optimism, then it should be referenced. It would be nice to see the evidence that supports the statement that, "The City envisions groundwater playing an important role in ensuring continued resiliency in its water supply portfolio". Document the past problems with ground water pumping and the optimism of future pumping Page 8-11 It is a dangerous precedent to use the information in this table to justify annual availability as it assumes that water will be available from these sources even during an extended drought. It would be good to know how many years water would be available if we had an extended drought. Document water availability during a time of extended drought Page 8-12 The document states- "The City maintains an Excelbased model that estimates a safe annual yield based on historical climatic conditi ons and reservoir operations. The model uses the historical record of inflow, evaporation, precipitation, and dow nstream releases. To determine safe annual yield, the model then calculates the maximum amount that could be withdrawn each year without drawing the reservoir below its minimum pool constraint. "This simply looks at how much water can be taken from each reservoir before reaching minimum pool. It does not indicate the number of years it will take to reach that point and what the City will do when it does. Present information that will show the number of years it will take for the city's reservoirs to reach minimum pool under severe drought conditions. Page 8-11 and 8-12 Safe Annual Yield It is not clear which years are used to calculate Safe Annual Yield (SAY). It is interesting to note that in 1988 "the critical drought period that controlled the safe annual yield was the 1946-1951 drought. In 1991, the model was updated to incorporate the hydrologic conditions experienced during the 1986-1991 drought" Then we have the drought of 2006-2016. Things appear to be getting worse. I believe that the Safe Annual Yield should be calculated using the amount of rainfall from the 2006-2016 drought. If we are truly looking at a worst-case scenario that would be it. Use the worst-case scenario to calculate Safe Annual Yield During the last drought we heard that the City had between 4 and 6 years of water left in our system. It would be interesting to show some calculation that showed how many years of water the system would have if we had more years like 2013 when we had just 3.8 inches of rainfall. The use of Safe Annual Yield is only one data point in calculating the reliability and availability of our water supply. Nowhere in this document or in other documents generated by the City tell us how many years of water are available if we experienced a series of low rain years like 2013. The term Safe Annual Yield makes us think that we will have a source of water in perpetuity but during the last drought we were told that our supply would only last for 4 more years. That is not forever. At best the Safe Annual Yield is simply a probability that water will be available, and this document should tell us what that probability is. This document and city planning documents must understand this reliability factor to adequately plan for a perpetual supply of water. 2 Page 8-21 Table 5 Reliability Reserve is a variable figure and should be estimated at buildout. It should be based on buildout population and not current population. Change this calculation to build out population. Page 8-22 "A 5.2.5 Paying for Water for New Development New development shall pay its proportionate or"fair share" f or water supplies, expanded treatment and distribution system capacity and upgrades." ----this does not include sunk cost to make sure water will be available for these users. All sunk cost should be appropriately attributed to the cost for these new projects. This should be a policy for every new project big or small in the City. New growth should pay their full and fair share to mitigate the impacts they will create. The use of the term "Build— Out" population is misleading and should not be used. This number is the estimated population in 2050 which is the horizon for the current general plan. Using the term "Build-Out" implies the end of building in the city of San Luis Obispo while it is actually the end date of only the current LUCE. A better term would be 2050 estimated population or General Plan 2050 estimated population. There is a high probability that the City will continue to grow beyond the "Build-Out" date of 2050. Do not use the term Build Out to indicate the proj ections of the General Plan. A term like General Plan projections or General Plan horizon would be more descriptive of what this is attempting to communicate Page 8-19 Suggested programs to add 1. Include better Climate Change data in this document 2. Provide information that shows the number of years of adequate water the City would have under a continued drought condition. 3. Safe Annual Yield a. Provide scenarios of water availability and safe annual yield under multiple scenarios b. Develop data that better demonstrate the water availability during an extended drought based solely on the data from the 2006 —2016 years or a worst-case scenario based on the rainfall from 2013. c. Calculate the number of years the City could provide water once it dips into the reliability reserve d. Add in water loss for your calculations of Safe Annual Yield e. Present information that will show the number of years it will take for the city's reservoirs to reach minimum pool under severe drought conditions f. Document water availability during a time of extended drought g. Use the worst-case scenario to calculate Safe Annual Yield h. Present information that will show the number of years it will take for the city's reservoirs to reach minimum pool under severe drought conditions 4. Calculate sunk cost for new development to pay for water and waste water infrastructure and storage. Then fully attribute those cost to new development. 5. Document and quantify the impact the new Cal Poly Master Plan will have on the City's water supply. 6. Consider the impacts of climate change, drought, and siltation on the reliably of the City's water supply from Lake Nacimiento. 7. Document the past problems with ground water pumping and the optimism of future pumping 8. Revise City planning documents to delete the term Build Out to represent the proj ections of the current General Plan. 3 Thank you for allowing me to participate in this process. David Blakely 4