ALAKAI PLATEAU – To the untrained eye, the water level in Kawaikoi Stream, which drains a portion of the vast Alakai Plateau on Kauai, looks fine. The trained eyes and stream flow measurements by hydrologists with the state Commission on Water Resource Management (CWRM) tell a far different story.
“This stream is flowing at record low flows for the last seven to nine months. Right now, we’re at about 20 percent of normal flow for this time of year, which does not bode well for the dry season. This is typically the wettest part of the year,” explains Dr. Aryon Strauch, CWRM’s lead hydrologist.
Without significant rainfall between now and the start of the “normal” dry season, this winter’s drought conditions across much of Hawaii are expected to worsen significantly.
“We are seeing record-low flows in terms of the entire period of record on Kawaikoi, that’s about 109 years. In some of the East Maui streams, 105 years. But we’ve not seen low flows like this across the state to this extent ever before,” Strauch said.
Some streams are already completely dry and that’s affecting water availability for drinking water supplies, for traditional and customary practices, and for agriculture.
Water managers like Mike Faye, of the Kekaha Agriculture Association, will be faced with distributing a dwindling supply of water to ag users and unless conditions improve, expect some to be left high and dry.
“Our role is to take care of the infrastructure which consists of two ditch systems that come out of the mountains in Kokee – the Kekaha ditch and the in Kokee ditch,” Faye said.
The association also operates two hydroelectric plants which it maintains, along with 30 miles of power lines and 30 miles of roads. If water flows continue to drop, the power they produce could cease along with water delivery to the nine leasees on mauka lands above Kekaha and the Mana Plain.
That is 13,000 acres in total, which formerly supported Kauai’s plantation-era sugar industry. The agriculture tenants are licensed through the state’s Agribusiness Development Corporation.
“One of the benefits of having long-term data sets is being able to talk about the severity of the drought conditions being observed relative to 100 years of record, and by explaining that these are unprecedented flows,” Strauch said.
“For the last nine months, we’ve only had maybe 12 days of peak flow conditions, which is very unusual, and we can compare that to a normal year, where we might have 60 days of peak flow conditions. The availability of water is just severely limited. Despite the water flowing in the stream, it’s just not flowing very much,” Strauch continued.
While water from the Kokee ditch continues to spill into Puu Lua Reservoir, even without measurements, Strauch and his team can tell the volume is quite low. Every day the shoreline expands as water levels in the popular trout-fishing spot continue to drop.
Using sophisticated instruments and data from permanent stream flow measurement stations, the CWRM team regularly monitors conditions of 80 waterways statewide. The outlook is particularly bleak in West Kauai and in East and West Maui.
“Honokohau Stream, in West Maui, the medium flow for this time of year is about 20 cubic feet per second (CFS), or about 12 to 13 million gallons per day,” Strauch said. Last week the stream was flowing at eight to nine CFS, or five and a half to six million gallons per day, which was, a third or 25 percent of normal flows. Recent rains have improved the Honokohau Stream flow to 11.8 CFS.
Wailuku River in Iao Valley saw improved stream flow over the past week, moving from 15 CFS to 22 CFS.
“Normal flow is about 25 and again, these flows are supplying water for drinking water supply. They’re supplying water for in-stream values, and it becomes a real challenge to manage water demand and water availability when we’re trying to protect a number of competing public trust uses,” Strauch said.
Rain-rich East Maui is experiencing the same thing: record-breaking low stream flows. Maui County has already imposed various stages of water conservation because of the current water shortage and for what’s predicted across the summer and into the next wet season.
Strauch concluded, “Obviously this impacts people who are directly reliant on the streams. But long-term agriculture and other off-stream uses that may not be the priority of the public trust uses of water, they’re going to suffer, because we just don’t have enough water right now to meet the demands.”
He hopes late winter rains will continue to improve the water situation statewide, but in case that doesn’t happen, water conservation will be key, he said.
