Southcentral Alaska waterways survey finds widespread microplastics

Sea Grant fellow Joi Gross takes a water sample from Campbell Creek to examine it for microplastics. (Courtesy of Dyani Chapman)

Microplastics are everywhere. The tiny fragments of polluting material from things like clothing fibers, fishing line, textiles and other harder plastics can accumulate and build up in waterways. 

A study released Thursday by the Alaska Environment Research and Policy Center examined microplastic content in various water sources across Southcentral Alaska, from rivers and lakes to tap water in three different Anchorage neighborhoods.

Dyani Chapman is state director of the environmental advocacy nonprofit and co-authored the study. She says microplastics can have serious impacts on the state’s ecosystems. 


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This interview has been lightly edited for length and clarity.

Dyani Chapman: So microplastics, one of the first things that can happen is they can be mistaken for food by small organisms. So zooplankton, fish, even birds. And they can cause problems with their digestion, so lacerations, or they can cause just digestive problems more broadly. And then, they can make their way up the food chain. 

And then plastics contain some chemicals that are endocrine disruptors that can impact people’s hormones and cause developmental problems, fertility issues, reproductive problems. And that can happen with wildlife as well, when they’re in high enough quantities. And then plastics can also, with that, there are some studies that have indicated that they can cause changes in behavior.

So salmon that are exposed to microplastics, there was a study where they fed less after they were exposed to those microplastics. They were less adept at avoiding predators, and they also had decreased mobility. And then when you have an organism eating a couple pieces of microplastic. And then, another one, eating more, and then they bioaccumulate up the food chain. It could get to a level where it could cause problems for larger wildlife or for people and cause fertility issues, organ issues, reproductive problems, cancer. There’s a whole bunch of different health impacts that are in there.

Wesley Early: So your study was limited to Southcentral Alaska waterways. Can you describe where you were looking for microplastics and what you and your team found?

DC: So I was working with Joi Gross this summer; she was a Sea Grant intern. And we looked at a whole bunch of different sources around Southcentral. There were places in Seward and Homer, sort of working our way up along the coast there, so Ninilchik. And then we were looking at some that were outside of Soldotna, around Kenai Lake, and then up (to the north). We tested a whole bunch of different sources in Anchorage, including tap water in a couple of locations, and then a bunch of spots in the Valley as well. So Big Lake, Nancy Lake, the Matanuska (River), the Little Susitna River, sort of trying to get a pretty broad set of samples. 

WE: And what did you find? 

DC: They all had microplastics. One hundred percent of our samples, we took 39 altogether, had microplastics in them, which was pretty disappointing. I went into this study definitely assuming that there would be some microplastics. Plastic pollution has been found really all over the world, on top of Mount Everest, in the Mariana Trench, so I assumed that there would be some microplastics. But as the summer progressed, and we were testing samples, it became really disappointing that we didn’t find even one example that was free from that pollution.

(Moving left to right, top to bottom) Fibers from Lake Wasilla, fiber wrapped around a film from Sand Lake, film from Tern Lake, fiber from tap water in the U-Med neighborhood of Anchorage, fibers (likely fishing line fragments) from Kenai Lake, fiber from the Little Susitna, fiber from University Lake, fibers from Kepler Lake. (Courtesy of Dyani Chapman)

WE: Can you talk about where this microplastic pollution is coming from, because you note that a lot of the microplastics can get absorbed into clouds and come back down in like rain or snow?

DC: We don’t know exactly where the microplastics came from in our study, because we identified and counted them and didn’t test them further. But the data does indicate a couple things about where some of the microplastics are coming from. The concentration of microplastics was actually higher in our less urban sources than in our urban sources. And our Anchorage sources actually had a lower concentration on average than our non-Anchorage sources. And Anchorage obviously has the highest population. That indicates that probably a fair bit of that microplastic pollution is coming in through rain and snow from other parts around the globe. 

However, we know that there are local sources for plastic pollution as well. We saw macroplastic pollution at several of the sites that we were collecting samples from. And I’m sure that everyone has seen plastic pollution out there when just hanging out in Alaska. And then there were a couple of locations that were sort of surprising. We tested a couple of popular fishing spots, including Kenai Lake, and there were actually over 50 microplastics per liter in that sample. And it was these little clear pieces that looked suspiciously like fishing line. So it does seem like there’s a couple local sources for that pollution as well. 

WE: So as microplastics become a bigger issue among scientists, what are you guys looking at as far as ways to get microplastics out of the water? 

DC: So getting the microplastics out of the water is a big undertaking. The thing that I would say is the most important step that we need to take right now is stop putting more microplastics in the water. I think a fun analogy for this is if your bathtub is overflowing, the first thing you want to do is turn off the tap, and then you can think about what to do with all that water. And it’s sort of the same thing with microplastics. We are actually increasing the amount of plastic that we’re using globally every single year, and that includes single use-plastics. So the biggest thing that we need to do is not make the problem worse. And then the question of how we actually get rid of the existing microplastic pollution can be tackled at that point in time.

WE: And for people listening who might be concerned that 100% of the water that they’ve been getting could have small plastics in it, are there things that individuals can do to at least reduce the amount of microplastics they’re ingesting?

DC: Yeah. So I did, out of curiosity, use my filter to see whether that would reduce the number of microplastics in my tap water. And I tested a handful of times and there were never microplastics in it, so that’s definitely an option as well.

Wesley Early covers Anchorage life and city politics for Alaska Public Media. Reach him at and follow him on X at @wesley_early. Read more about Wesley here.

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