2019-02-07 Hearing Transcript - Piilani Partners LLC SMA 18-070

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BUNN: And, for each of the aquifer sectors and systems that are on the drawing, the drawing identifies the sustainable yield. Could you explain what that means? NANCE: Okay, let's, let's start first with aquifer recharge and then get to the sustainable yield, because the sustainable yield is based on a percentage of what is computed as the recharge. So, they go through an exercise looking at rainfall, evaporative loss, surface runoff, and determine to where the best of their technology then available how much of that water went and infiltrated and became recharge to the aquifer. So, for example, I think I have some numbers here. For example, Onomea Aquifer has a sustainable yield of a 147 million gallons a day as determined by the State Commission on Water Resource Management, and that's based on a total recharge being 335 million gallons a day. And, how much of that recharge they determine to be sustainable yield by their methodology depends on how high the water level is in the aquifer itself. For example, if it's a low-level basal groundwater, three, four, five feet above sea level, they determine that 44 percent of the recharge is available as a sustainable yield, and they define the sustainable yield as the amount of water that can be extracted without deteriorating the quality of the aquifer or the structure of the aquifer. The reality is where the wells are located depends a lot of whether you can or can't achieve that sustainable yield, but for water levels that are much higher, they go up to saying the sustainable yield is as much as 75 percent of the recharge. BUNN: Thank you. So, I think you identified that for the Onomea Aquifer system, the Water Commission's estimate was that a 147 million gallons per day could be withdrawn without impairing the aquifer. What about the Hilo Aquifer system? NANCE: For the Hilo Aquifer system, they have a total, a calculated recharge of 793 million gallons a day of which 347 million would be available as the sustainable yield. REPLOGLE: Daily? Daily? NANCE: Yes. A lot of water. BUNN: So, I just want to make sure I understand this right. Water in an aquifer underground is not static. It's not like there's an amount kind of sealed within a vault. There's recharge coming in every day, and discharge going out every day? NANCE: That's—that's correct. It's a, it's a cycle depending on the areal extent of the aquifer from recharge to groundwater flow to ultimate ocean discharge can be much longer than a hundred years depending on the size and how long the process is to move through the formation and ultimately discharge in the ocean. BUNN: And, where does the recharge for the water in the Mauna Kea lavas come from? EXHIBIT D 11