Plastics Found in One of Hawaii’s Most Remote Streams

valley _SUP_sea to summit
Paddling up the Waimanu stream Photo: Plastic Tides

Adventure Scientists for the Global Microplastics Initiative reach the most remote corners of the globe to help us understand the extent of plastic pollution worldwide. Collecting freshwater samples will provide critical data that can identify sources of microplastics in order to eliminate their introduction into the world’s water supply. Christian Shaw and Céline Jennsion of Plastic Tides are long-time ASC adventurers and recently targeted the Waimanu Valley as the location for their next expedition.

Christian with his portion of the team’s gear. Photo: Celine Jennison
Muliwai Trail leading back to the valley.

The Muliwai Trail is considered by some to be the toughest hike in all of Hawaii. Located on the northeast coast of the island, the trail provides access to the isolated Waimanu Valley, which more people have likely seen from a helicopter than on foot. The remoteness and the lack of signage in the valley require careful planning and adept route finding to navigate it safely.

Moving further upstream to find a spot to sample. Photo: Plastic Tides

The difficulty of the hike limited, or maybe determined, the team’s choice of gear. To paddle upstream they decided to both ride on the same inflatable SUP and used this as their sampling platform. In order to cut weight, they foraged half of their food, relying on papaya and breadfruit cooked in seawater. They still ended up carrying 40- and-60 lb packs.

Dinner prep. The duo foraged for half of their food on the trip. Photo: Christian Shaw

The route Christian and Céline chose covered 22 miles and close to 16,000 vertical feet in just three days. They hiked back into the valley and paddled up the Waimanu Stream to take the samples as far inland as possible, making them the first ASC adventure scientists to collect freshwater samples from anywhere on the Big Island.

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Christian collecting ASC’s first freshwater sample from the Big Island. Photo: Plastic Tides

The results from their samples were at first glance encouraging. An average of 1.5 pieces of plastic per liter is well below our dataset average of 7. But the fact that microplastics were present at all in one of the most remote and least visited streams in Hawaii sheds some light on the need for urgency in our actions if we plan to prevent plastic from permeating all of the world’s freshwater.

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Meet the Author
Gregg Treinish founded Adventure Scientists in 2011 with a strong passion for both scientific discovery and exploration. National Geographic named Gregg Adventurer of the Year in 2008 when he and a friend completed a 7,800-mile trek along the spine of the Andes Mountain Range. He was included on the Christian Science Monitor's 30 under 30 list in 2012, and the following year became a National Geographic Emerging Explorer for his work with Adventure Scientists. In 2013, he was named a Backpacker Magazine "hero", in 2015, a Draper Richards Kaplan Entrepreneur and one of Men's Journal's "50 Most Adventurous Men." In 2017, he was named an Ashoka Fellow and in 2018 one of the Grist 50 "Fixers." Gregg holds a biology degree from Montana State University and a sociology degree from CU-Boulder. He thru-hiked the Appalachian Trail in 2004. Read more updates from Gregg and others on the Adventure Scientists team at Follow Adventure Scientists on Instagram @adventurescientists, on Facebook @adventurescientists, and on Twitter @AdvScientists.