In June 2024, the state Supreme Court ordered the Commission on Water Resource Management to revisit its findings in a contested case over stream flows in Nā Wai ʻEhā, the four great waters of central Maui.
That was the second time that CWRM’s decision on allocation of water in the area was rejected by the court.
This time, the court determined, among other things, that the commission had not fulfilled its obligation to restore stream flows in the wake of the closure of the HC&S sugar plantation, which for more than a century had been receiving stream water through a series of ditches and diversions.
Instead, in making its findings in what has been called Nā Wai ʻEhā II, CWRM relied on interim instream flow standards that had not been changed since 2014. Referring back to CWRM’s decision and order in the first contested case, the court noted that the commission had found that the interim instream flow standards should “increase incrementally over time.” That finding, the court continued, suggested that time would be needed to “properly study the effects of stream flow restoration, but the commission has not sought out the information it needs through additional scientific studies or otherwise.”
“Rather than proactively addressing the historic opportunity to restore stream flows,” the court wrote, the commission’s decision “appears to be the result of a passive failure to take the initiative to protect the public trust in light of HC&S’s closure.”
But well before the court released its 134-page-long ruling, CWRM staff had begun to undertake the kind of studies, of stream hydrology and ecology, that could underpin future allocations of stream water that the commission would need to make in deciding the remanded contested case.
In October, Ayron Strauch of CWRM’s Stream Protection and Management Branch, gave the commission a brief overview of a report that he and staff hydrologist Cody Chacon had authored and published on the commission’s website in August.
There were “two takeaways” from their work, Strauch said. “We have approximately 10 to 15 percent less water … across the board, based on the 20-year period of record from 2004 to 2023.”
The presentation was brief, but the 62-page report has detailed information on the interaction of streams with groundwater, the response to restored stream flows, the biological resources supported by the streams, and years of streamflow measurements.
Commission member Hannah Springer thanked Strauch for the updated information.
“That came up in past discussions about how long contested cases take and dealing with old statistics and old hydrological data that may not be relevant today,” Strauch replied. “We’re trying to be a little bit more proactive in developing these data sets.”
The only member of the public to comment on Strauch’s presentation was Hōkūau Pellegrino, board president of Hui o Nā Wai ʻEhā. He thanked Strauch and his team, but added that this year, “we’re experiencing an unprecedented drought. We’re seeing stream flows much lower than the stream flow standards that have been put in place. We’re seeing base flows lower than anything we’ve experienced in the record.”
In the introduction to the report, Strauch and Chacon write, “Long-term shifts in the magnitude and distribution of rainfall across Maui have resulted in reductions in baseflow and an increase in the frequency of low-flow conditions. This is evident in declines in the median and low-flows observed at continuous-record gaging stations in Nā Wai ʻEhā and has consequences for water availability to meet public trust uses, including habitat for aquatic species, water for domestic use, and traditional loʻI kalo production dependent on the delivery of water through irrigation systems.”
The report details just how significant the reductions in stream flows have been. To give just two examples: Monitoring stations on Waiheʻe River show that in the 2004-2023 period, median flows (Q50) declined 9.6 percent from the median flows recorded from 1984-2007. The magnitude of the Q70 flows (the volume of water in the stream 70 percent of the time) declined 11.4 percent. The Q95 flows dropped 8.8 percent.
Flows in the Wailuku River showed a similar decline in the two periods: 12.8 percent in the Q50 flows, 11.1 percent in Q70, and 11.8 percent in Q95.
— Patricia Tummons
Leave a Reply