Lake Waiau is a small lake just below the summit of MaunaKea volcano on the Big Island of Hawaiʻi. It also is one of the highest lakes in the United States with an elevation of 13020 ft (3,970 m), the only alpine lake in the state of Hawaiʻi, and, after the evaporation of Ka Wai o Pele (green lake) in 2018 and the short-lived lake in Halemaʻumaʻu crater in 2020, the only lake on the Big Island.
Lake Waiau is also very interesting both from a mythological and scientific perspective. For example, it started draining in 2010 and had almost disappeared in 2013. Luckily, it started filling up again with a few big winter storms in 2014 and had all but filled up again by 2018.
Oh, and did we already mention the part where it also still isn’t clear exactly why the lake exists?
If you are interested in visiting Lake Waiau yourself, we recommend the directions on the Big Island Hikes website.
Why is Lake Waiau a Lake?
Believe it or not, but the existence of lake Waiau is still somewhat of a mystery! Lakes are rare features among the volcanic slopes of the Hawaiian island chain. The few basins that could hold water on these slopes are normally on top of permeable lava flows or cinder and ash, which favor the rapid seepage of precipitation. Yet, Lake Waiau exists. How does this happen?
There are currently three explanations that offer insight:
- A possible explanation for the lake is that sulfur-bearing steam from MaunaKea altered the cinders and ash locally to fine clay minerals that reduce the permeability of the soil. This reduced permeability can account for the retention of water, which in turn leads to the formation of Lake Waiau.
- A second explanation involves the glacial past of MaunaKea. Long ago, the summit of MaunaKea hosted glaciers. Fine-grained ash beds are commonly produced when rising magma interacts with shallow groundwater or surface water. If an eruption occurred beneath glacial ice, these ashes could have been produced, and, up to this day, slow the seepage of water from the small crater.
- The last explanation posits that the impervious layer beneath Lake Waiau is made of permafrost. Permafrost has been found to exists at the MaunaKea summit cone. Shallow holes drilled 30 years ago passed through this permafrost at depths of 10 m (33 ft).
Read more about these explanations in this volcano watch article (2003).
Is Lake Waiau Disappearing?
In the recent years the surface area of lake Waiau has diminished in size, hitting an all-time low in October 2013. Since then, the lake has returned to its normal size. Recent research presented in the USGS 2015 report “Satellite Monitoring of Dramatic Changes at Lake Waiau on Mauna Kea Volcano—Hawai‘i’s Only Alpine Lake” [pdf] suggests that although the recent fluctuation in lake size has been extreme, its cause is rather commonplace: not enough rainfall.
This is illustrated in Figure 8 of the report, which we have reproduced below, and with two photos taken in 2013 and 2016. The report concludes that the severe drought, which has plagued the Hawaiian islands between ~2008 and ~2014, did not allow the lake to compensate losses from evaporation and seepage from the bottom of the lake.
Lake Waiau in the Hawaiian Cultural Tradition
Lake Waiau is sacred in Hawaiian tradition and has cultural and spiritual significance to many Hawaiians. It is part of the summit of MaunaKea, which is considered the umbilical cord (“piko” in the Hawaiian language) that connects the Earth to the heavens. The lake is most likely named after Waiau, one of the four snow goddesses know in Hawaiian mythology. According to this mythology, Waiau used to bathe in lake Waiau.
Read the story “Pele and the snow goddess”, which is translated e.g. here, for a deeper dive into Waiau and Hawaiian mythology.
Lake Waiau Interesting Facts
- Lake Waiau, in the MaunaKea Ice Age Natural Area Reserve, is the only alpine lake in the Hawaiian island chain, lying within Puʻu Waiau at about 3,969 m (13,020 ft) elevation. Besides the significant archeological and geological features, Lake Waiau has cultural and spiritual significance to many Hawaiians. [source]
- Based on this research which covers the past 200 years, the historical lake surface area has typically ranged from 5,000 to 7,000 square meters, with a dramatic plunge in 2010. The cause for the near disappearance of the lake is most likely the severe drought recorded on the Big Island starting in 2008
- Explanations for *why* the water remains in the lake include either a layer of permafrost or soil-altering effects brought on by volcanic processes. Read more about these reasons here.