Nature Center dives deep into watershed health

A grant will let the organization add stormwater testing to their study of the island’s stream health.

The Vashon Nature Center had heartening news to share on island stream health in 2023, and this year will embark on even deeper research into the health and future of the island’s watershed.

In December, the Nature Center received a renewal of a $70,000 King County “Waterworks” grant, which will let the organization this year add stormwater testing to their study of the island’s stream health. That means that in 2024, for the first time, they’ll be able to perform limited testing for “forever chemicals” like PFAS and 6_DPP Quinone (the tire chemical harmful to salmon).

The funds help the Nature Center collect data in the field and pay lab fees for analysis. The grant also means the Nature Center can contract with local water expert Michael Laurie, who can visit homes on the island to assess any ponding, flooding, runoff or erosion issues.

That matters, Nature Center founder and Science Director Bianca Perla said, because Vashon’s town sits on the headwaters of the island’s largest salmon-bearing creeks: Shinglemill and Judd.

“Anything that happens within that that area really matters downstream,” she said.

Nature Center teams have, in 2019 and 2020, studied stormwater runoff from those creeks to see how well the environment can soak up pollutants like copper, mercury and arsenic. They found that the big creeks are “mostly attenuating that stuff pretty well,” she said, keeping dangerous ingredients mostly out of the Puget Sound and instead deposited into sediment and the forest.

Watersheds are often most at danger during intense storms, Perla said, as runoff water floods into creeks and Puget Sound too quickly for the environment to cleanse it. The bigger the storm, the less creeks can attenuate that floodwater.

And Earth’s changing climate means this region will likely see more and more intense winter storms, which are difficult for the island to absorb, she said. That also means the island’s aquifers aren’t recharged as efficiently, which affects the island’s drinking water supply and the health of fish and invertebrates in Puget Sound. Salmon eggs, for instance, can be swept away in high flows, Perla said.

“We have to be more vigilant about attenuating,” she said. “Using more rain gardens (to) hold the water, mulching, forest cover — anything that can hold the water is going to be more important as we go forward.”

Encouraging signs for stream health

The Beachcomber has previously reported on encouraging signs for stream health on the island, but Perla offered a more in-depth look at how our watersheds are faring.

Of the many ways to measure stream health, researchers like Perla often use bug health — because it’s such a comprehensive marker.

“It tells you just generally about the quality of the stream related to how many different types of bugs can survive there,” she said.

The island’s streams, which have, on average, been tested for about a decade, bear good news for the environment on Vashon, Perla said: The bug health indicators are showing either steady or improving trends in island watershed health.

“I think this is a really neat story here on the island,” Perla said. “We’ve been doing a lot of restoration. Private landowners have been changing habits in all these watersheds. One of our big questions was ‘How are our streams doing in light of the changes?’ … and it looks like they’re doing much better, or at least not declining.”

Tahlequah and Christensen creek in particular are in “really good condition,” she said, with high levels of forest area to soak in runoff chemicals. Judd and Shinglemill are in “fair” condition, she said; for Shinglemill in particular, the steep geography makes the creek more vulnerable to stormwater flooding.

The work is made possible with the help of community volunteers and local students. Last year marked the 10th anniversary of the Nature Center’s educational science program, which brings out McMurray sixth-graders to sort the invertebrates found in Shinglemill Creek. The youth then put together a report on their research.

“It’s a good learning experience for the kids,” Perla said. “Some of them have no idea that these little bugs exist in the creeks.”

The Nature Center released a report in March 2023 summing up 20 years of research, which you can read here.

Getting fishy

Another angle for measuring watershed health is the Nature Center’s community and volunteer-driven salmon watch and trout trackers programs — measuring the rate at which the iconic Pacific Northwest fish are born and return to spawn in island creeks.

Vashon has resident cutthroat trout that live in the island’s creeks and never return to sea, as well as sea-run populations, Perla said. Those trout are smaller and more widespread on the island than salmon.

A 2001 study by Washington Trout was the last truly comprehensive study of trout populations on Vashon, Perla said. But this year, the Nature Center will be studying the prevalence of spawning trout with the help of volunteers, the Coastal Cutthroat Trout Coalition and scientists from the state Department of Fish and Wildlife. (The fishes’ spawning season is January to May.)

Those trout fly under the radar compared to salmon, Perla said, but “they’re really more tied to small streams, especially, and I’m really excited to learn more about them.”

The Nature Center will release a broader report on salmon watch data from the last two decades soon. Preliminary data, Perla said, indicates there are small, fluctuating runs in Shinglemell and Judd Creeks, which are dependent on ocean and creek health.

Shinglemill’s salmon runs have gone from “basically none” to a small but steady run in the last 15 years, Perla said. Judd’s run continues to vary from year-to-year. Both runs are small and remain vulnerable, she said, and will rely on keeping streams and estuaries healthy.

There are records of salmon exploring other creeks such as Fisher and Christensen, which is a good sign, Perla said: “Even if they’re not spawning there, they’re coming in once in a while … if enough of them do, they could establish a population.”

Salmon watchers collect DNA from the fins of salmon that spawn and die, sending that DNA for testing at the Fish and Wildlife genetics lab. The question they seek to answer is: Where are these salmon coming from?

Everyone learns in grade school that salmon return to the streams they were born in to spawn the next generation, Perla said.

But salmon have individual personalities. Some go rogue, seeking out new streams instead — and Vashon’s salmon seem to fit that bill, she said.

“What we’re noticing is that we think at least our present day populations are built from strays of other populations, because they carry the genetic signature of nearby creeks on the mainland,” Perla said. “Our populations seem to be building up again from these exploratory fish.”

A previous version of this article erroneously stated that the Nature Center has tested for “forever chemicals” in Vashon streams before. This has been corrected; 2024 will be the first year the Nature Center tests for these chemicals in the streams. We regret the error.