Much ado has been made by the parties in the Na Wai `Eha contested case hearing over a study being conducted by the U.S. Geological Survey to help the Water Commission gather data needed to establish instream flow standards for `Iao, Waihe`e, Waikapu, and Waiehu streams.
In 2006, the USGS began the study, which includes analyzing existing information, conducting baseline surveys, recording stream flow and temperature, monitoring the frequency with which certain reaches were dry, recording any aquatic species, and collecting habitat information.
According to testimony submitted by USGS hydrologist Dewlyn Oki, a witness for Hui O Na Wai `Eha/Maui Tomorrow, photographs of the study areas revealed that between September 2006 and July 2007, in their lower reaches, North Waiehu Stream was dry about 79 percent of the time, `Iao Stream was dry about 70 percent of the time and Waikapu was dry about 37 percent of the time.
Oki states that a critical component of the USGS study is the need to restore the streams enough so that they flow continuously from the mountain to the sea.
“Controlled releases have been and continue to be requested to allow measurements of streamflow, infiltration, and physical habitat (and possible recruitment and larval drift) for different flow conditions in sections of the stream that commonly are dry under diverted conditions,” Oki writes.
To maintain flows near the coast, Oki recommends that 9.5 to 22 mgd be incrementally released into `Iao Stream from the `Iao/Maniania Ditch diversion, 10 to 30 mgd be released into the Waihe`e from the Spreckels Ditch diversion, and 2.5 to 4.5 mgd be released into Waiehu from the North Waiehu and Spreckels ditches.
While the total amount the USGS wanted released was at most 56.5 mgd, it was not proposing that the water be released all at once or for more than a month at a time. According to a proposed schedule, the releases would occur from January through September 2008, with the largest release, 30 mgd, to be made during March.
Hui O Na Wai `Eha and Maui Tommorrow say the releases are necessary and must be done soon.
Earthjustice attorneys Isaac Moriwake and Kapua Sproat, representing the two groups, have noted that field work will end in 2008.
“These studies, of course, are not being conducted for USGS’s sake, but rather to help the commission fulfill its mandatory duty to establish ‘meaningful,’ ‘bona fide,’ and ‘proper’ instream flow standards,” they say in arguments filed with the commission earlier this year.
Although it supports the releases, Maui County has asked that they be timed and structured so that they don’t adversely impact its operation of the `Iao surface water treatment plant.
WWC and HC&S, on the other hand, have argued vehemently against the USGS proposal, claiming that the proposed releases would leave little to nothing for existing users. Testimony by WWC’s ditch system manager Clayton Suzuki suggests that it’s not possible to release a set amount of water because flows fluctuate.
“For example, on the Waihe`e Ditch gauging station, the flow rate can vary from a low of 1.8 mgd to a high of 24.7 mgd in a single 24 hour period… To achieve a constant flow for any period of time more than a few hours, it would be necessary to construct a temporary dam across each stream to create a reservoir that would serve to stabilize the flow,” Suzuki states in his written testimony. He also adds that the USGS never contacted him about getting stream data.
Last October, however, the USGS met with the parties involved in the case and determined that the data it wished to receive from the controlled releases could be obtained if the release was 3 to 4 days in length. Since WWC stops diverting each stream for a week or two each year to do maintenance, Suzuki stated that it would make the most sense for the USGS to conduct these studies during that time.
— Teresa Dawson
Volume 18, Number 6 December 2007