Reporting on the March 2 Land Use Commission hearing on Hoopili, D.R. Horton-Schuler’s project to develop 11,750 houses on 1,554 acres of prime ag land in Ewa, Sophie Cocke wrote, “No one can accuse Bill Tam of being short on words.”

I was not at the hearing, but I am familiar with Tam’s practice of evading questions by jumping from topic to topic and sometimes even asking interlocutors to consider legal phantoms and arcane hypotheticals.

“He discussed,” Cocke continued, “climate change, threats to Hawaii’s watersheds, disputes over water rights, runoff, plantation water systems dating back to 1900, weather cycles, water quality issues, pesticides — everything but Hoopili.”

Andrew Gomes, of the Star-Advertiser, reported that “Tam raised concerns that models to predict water availability are outdated, but he refrained from saying whether he thought enough water exists for Hoopili.”

Tam, the deputy director of the Water Resource Management Commission, often referred to as the Water Commission, appeared to be less helpful than he could have been. Was he under orders to testify as he did, or was he just being Bill Tam?

Or was he being an akamai, turf-conscious bureaucrat who wasn’t quite ready to tip his hand?

Tam does not have a vote on the Water Commission. He was appointed deputy director by the chairperson of the commission, the director of Land and Natural Resources, who in turn was appointed by the governor. The chairperson of the Water Commission, not inconsequentially, also serves as chairperson of the Board of Land and Natural Resources. As staff director of the Water Commission, Bill Tam is a state employee, fully on the state payroll. He is not a volunteer commissioner who serves without compensation.

Unlike his predecessors, all of whom except for one (I believe) was a professional engineer, Tam has a legal background. He prefers words and arguments to numbers and equations. He is a lawyer who specializes in land- and water-use law. He served for many years, maybe for as long as a decade, as the deputy attorney general assigned to the Water Commission. In Hawaii, he is the go-to guy on water-resource regulation.

Outdated though the Water Commission’s sustainable-yield models may be, they could have reminded the Land Use Commission that it should not ignore the valuable resource that lies hidden, underground, below the project site.

At the least, Tam could have identified the aquifer beneath the proposed development project — it’s a very busy one — and explained how much water was withdrawn at the time the model was prepared. He could have explained the concept of sustainable yield.

(HRS Chapter 174C, the State Water Code, defines sustainable yield as “the maximum rate at which water may be withdrawn from a water source without impairing the utility or quality of the water source as determined by the commission.”)

In addition, Tam could have said how much water is being withdrawn today and how much will be required by Hoopili, as a percentage of the aquifer’s sustainable yield, when the project is completed. He could have explained if the water recharge area has shrunk owing to recent development and how further shrinkage — along with recent rainfall trends — will affect the aquifer’s future estimated sustainable yield. A key question that requires some sort of answer is: might climate change bring about drought conditions?

When the Ewa plain was used to grow sugar cane, the Oahu Sugar Company irrigated fields using a system of open ditches. Well water and water from the Waiahole Ditch was plentiful, and water flowing in the open ditches was lost through evaporation. However, the plantation’s irrigation system provided an important benefit: it returned water to the aquifer, replenishing it for future use.

In an earlier article on Hoopili and Bill Tam (“State Supports Hoopili, But Top Official Will Testify For Opponents,” March 1, 2012), Sophie Cocke reported, “The Honolulu Department of Planning and Permitting testified that there is enough water to accommodate Hoopili. And D.R. Horton has stressed that 12 million gallons daily of potable water is reserved solely for the Ewa region. The development at full build-out would consume an estimated 3.9 million gallons.”

Is there enough water to accommodate Hoopili?

Almost a year ago, Tam requested the Water Commission to authorize William Aila, the chairperson, to enter into an agreement with the U.S. Geological Survey to “update estimated ground water recharge distribution for the island of Oahu.”

The results of the study will help the Commission to update the sustainable yield of the Pearl Harbor aquifer, on top of which Hoopili will be built. The March 16, 2011, request notes that “There have also been significant changes in land and water use, in particular the cessation of plantation agriculture and an increase in the urbanization of former agricultural lands and other previously-undeveloped lands. Such large-scale land and water use changes can greatly affect water budgets.”

Attachment 1 of the request notes that “Chloride concentrations of water pumped by some wells in the eastern part of the Pearl Harbor aquifer have risen in recent years, although recent pumpage from the area is near the CWRM-estimated sustainable yield for the area. Decisions related to future infrastructure development and alternate sources of fresh water, including desalinization, will depend on the long-term sustainability of the groundwater resources in the Pearl Harbor aquifer.”

(Chloride concentrations refer to seawater intrusion into the fresh-water lens contained in the aquifer.)

Tam’s request recognizes that Hawaii’s climate is changing. A USGS study of stream- flow data found “statistically significant downward trends in annual base flow during the study period at all seven stations. This finding corresponds to independent research on rainfall by the University of Hawaii that also documented downward trends in rainfall during this period.”

The new USGS study was to begin in April of last year, be approved this August, and published online in September. The work plan indicates that a first draft will be completed this month, in March.

Through the permitting process, the Water Commission regulates the amount of water that is withdrawn from the Pearl Harbor aquifer. Calculating the amount of water that enters the aquifer is complicated. Forecasting the aquifer’s sustainable yield in a time of climate change will be tricky. The Water Commission, in carrying out its duties under the public-trust doctrine, can — as Bill Tam knows — require that an adequate amount be set aside as a conservation reserve. Nature, which is deaf to the siren calls and assurances of lobbyists, can be a stern disciplinarian, indifferent to human aspiration and desire. A drought, when it occurs, is a drought is a drought.

About the author: Warren Iwasa was the executive director of the Review Commission on the State Water Code, State of Hawaii.