Stream Bug Stories:

Watershed Wellness on Vashon Island

Canaries in the Water System

Healthy streams are important for our local drinking supply and integral to supporting native plants and wildlife. The condition of our streams can also tell us about the health of island aquifers and the surrounding waters of Puget Sound. All of these water sources are connected through drainage basins called watersheds that collect and channel rainwater and snowmelt. Because of this connection, much of what is in our surface water as streams or ponds travels to or from our aquifers. Streams also drain into the Puget Sound at their end point influencing the health of our marine waters in many ways. This means streams are “canaries in the water system” for the freshwater on our island and the marine waters surrounding us.

What is a watershed?

A watershed is a land basin that channels rainfall or snowmelt to creeks, streams, rivers and eventually to an outflow point like a lake, bay, estuary (like Puget Sound), or the ocean. Some watersheds are very small, but some encompass thousands of square miles.

For example, Shinglemill creek watershed on Vashon (shown in this photo) is about 3 square miles as compared to the Columbia River watershed that is 260,000 square miles.

Explore! Drop a water droplet anywhere in the world and see where it goes!  Try this app to explore watersheds everywhere  (Vashon is too small but larger watersheds are shown in detail).

photo credit: Ed Rutledge
photo credit: Ed Rutledge

What do watersheds do for you?

Healthy watersheds provide habitat for wildlife and plants that live on the land and in the streams. Together this functioning system and all its parts provides clean, cool, water that everyone can enjoy for both sustenance and recreation. Healthy watersheds also support the long-term health of Puget Sound when they discharge clean water into estuaries, bays, and other marine areas.

photo credit: Bianca Perla
photo credit: Bianca Perla

What do you do for watersheds?

Just by living and creating spaces for ourselves, people can do things that compromise or benefit watershed health. There are many different impacts that can happen directly in the streams or on the lands that drain into the streams. For example, if trees are cleared or areas of the watershed are paved or graveled, “impervious surface” area in the watershed increases. When this happens, rainfall no longer gets intercepted and slowed down by vegetation and it can no longer sink into the ground. Instead, rain runs along the top of hard surfaces picking up sediments and pollutants.

If water can no longer sink into the ground, the sheer volume of water in a large storm can overwhelm streams causing high flows and flooding. These high flows can wash out stream invertebrates, destroy salmon redds (gravel nests where eggs are laid), clog fish gills, damage human constructions, and erode streambanks. 

Besides high flows and sediments, pollutants in the form of chemicals, heavy metals from tires, excess nutrients, pesticides and herbicides can flow into streams from surrounding lands. This runoff is called stormwater and it  is the number one silent killer in Puget Sound  for stream and marine life.

As keystone inhabitants of Puget Sound ecosystems, humans can act in ways that minimize our impacts. And not only that, we can provide benefits to the watersheds where we live.

photo credit: Mary Bruno
photo credit: Mary Bruno

Promising people

People can act in promising ways that bolster watershed health. On Vashon we are lucky to have many generations of islanders that care about our streams.

The data you read about in this report was lovingly collected over a period of 20 years! First by King County scientists and later by community members and students alongside Vashon Nature Center scientists. 

Long-term monitoring

McMurray students, Vashon-Maury Island Groundwater Protection Committee, Vashon Nature Center, King County, and adult volunteers teamed up for a multi-year effort to figure out why Shinglemill had low biological integrity scores. Through sampling for benthic invertebrates, we learned that high flows that carry sediments and pollutants are likely impacting stream life in Shinglemill creek. Plans are now underway to install rain gardens in downtown Vashon to help slow and clean water from town before it enters Shinglemill Creek.

Volunteer to help with stream surveys: info@vashonnaturecenter.org or  join our volunteer email list .

Groundwater Protection committee member Frank Jackson spearheaded an effort to install carwash kits at IGA. If you are planning a carwash please be sure to ask IGA staff if you can use the carwash kit stored there to help keep runoff from entering the creek system.

Re-forestation

Vashon-Maury Island Land Trust stewards and volunteers have planted over 10,000 trees in Judd and Shinglemill creek watersheds. These trees are growing up to shade the stream, slow down run-off in storms, and provide habitat to many forest animals and birds.

Many private landowners have planted trees on their own properties as well which adds to this effort and increases the benefits for all. Learn how to care for your forest. Look for information on the annual Land Trust sponsored Forest Stewardship Course.

Sharing the knowledge

Island artist Ela Lamblin, after learning about the importance of stream bugs as indicators of stream health, created this fantastic moving sculpture called "Indicator Species" to raise awareness of these important invertebrates. The sculpture was displayed at Burning Man and now resides at Dragonshead cider. Where will this magnificent stonefly be seen next?

Log restoration

King County basin steward Greg Rabourn and team have worked hard to install several log jams on Judd and Shinglemill creeks.

Due to habitat conversions like logging, farming, and urbanization most Puget Sound streams are starved of the large wood and fallen trees that used to line and cross these waterways. Scientists call these large woody debris and cite their importance as food and habitat for a variety of stream bugs and shelter for fish. They change the character of the stream helping to slow down high flows and create deeper pools that allow fish to rest from the current or dive deep on hot days.

Stormwater assessments

Through a Waterworks grant sponsored by Vashon Nature Center, long-time islander Michael Laurie offers free on-site stormwater control assessments for anyone living in the Vashon Sewer District. To date he has helped make improvements that curtail run off on several private and business properties in downtown. Email:  mlaurie@mindspring.com  for more information.

Stream Bug Stories

In this storymap we explore the question: how are our watersheds doing? We want to know: Are our stewardship and restoration actions making an impact? Where do we still need to work on improving? To answer these questions we asked for help from some important members of the stream ecosystem: stream bugs!

Stream bugs like this little stonefly from Shinglemill Creek, can tell us a lot about how our stream are faring and what we can do to help them stay healthy.

When you are sitting by a stream watching the water flow by, have you ever wondered about what is living below the surface? It is an amazing world filled with grazers and predators, decomposers and little engineers all living out their daily dramas amongst the rocky, silty, muddy or sandy bottom. The stream floor is teeming with life and this life provides important ecological services to us. Stream bugs help break down leaves and wood, filter the water, and provide food for fish, birds, and other animals.

Some stream bugs are more sensitive to certain impacts then others. For example, some are sensitive to high temperatures, others to pollutants, others get swept away in high stream flows, and some are extremely tolerant and can live in almost any stream condition. So, we can learn a lot about how the watershed is doing just by noticing which bugs are in the stream and which types are rare or missing!

Meet the Stream Bugs!

There are many different types of species living in the sediments of the stream bottom. Most of these are the aquatic larval stage of what will one day become a terrestrial invertebrate. Here are a few of the key players:

Stoneflies (Plecoptera) need cool clean oxygenated water to survive. They have complex mouths with several pincer-shaped pieces. Some stoneflies (like the one pictured here) are grazers eating algae off rocks and wood, but most are predators eating other stream bugs. Stoneflies tend to decline when the water becomes warm or less oxygenated.

Caddisflies (Trichoptera) need lots of wood and a complexity of different stream habitats. Many caddisflies are incredible engineers able to build protective cases out of sand, fir needles, tiny wood chips or little pebbles. In streams that have adequate wood and high habitat diversity you will find many different kinds of caddisflies. In streams that have more simplified habitat the diversity of caddisflies will not be as high.

Mayflies (Ephemeroptera) are sensitive to heavy metal pollution, some mayflies increase with high nitrogen, and some get swept away in high flows. Mayfly larvae tend to hatch into their flying adult stages all at once, yet they only exist in these swarms for a few days before they die, thus the Latin name Ephemeroptera.

Black Flies (Diptera) are tough. They do just fine in hot temperatures and silty or polluted conditions. Black fly larvae stick themselves to rock surfaces using a very strong silk with a waterproof adhesive. Then they unfurl their feathery mouthparts to filter feed in the currents. Blackfly larvae exist in almost every stream, but their proportion increases in more degraded streams as sensitive species drop out.

Community Science in Creeks!

Twenty years ago King County water quality scientists started to use stream invertebrates to score several island creeks and learn about watershed health. By 2013 it was becoming hard to sustain this effort on the scale that it was started. The Vashon-Maury Island Groundwater Protection committee, recognizing the value of this long-term monitoring program in providing key knowledge of our water resources, partnered with Vashon Nature Center to bring in the help of community scientists to assist in keeping this long-term effort going.

Thanks to this we now have a data set that exceeds 20 years in some creeks! Because creek conditions are naturally variable, long-term datasets like this are essential for us to see trends pop out despite the year-to-year variation that is natural in these systems.

In the next sections let’s dive into the data and see how well we can answer the following questions:

·         How healthy are our watersheds?

·         Are the stewardship efforts we are all working so hard on actually paying off?

·         Is there anything else we can do to help contribute to the long-term health of our island watersheds?

Let’s see what the stream bugs are whispering to us...

Island watersheds sampled for stream invertebrates. Entire sampling period spans from 2000-2022 but is shorter for some creeks. Average Benthic Index of Biotic Integrity Score (B-IBI) over all sample years is shown in corresponding color. Raw data can be found at pugetsoundstreambenthos.org

How are we doing?

Watershed map showing all watersheds on the island with dots showing sample sites where stream bug samples have been taken. The average score of each watershed over the years sampled is shown in color.

Our best scoring watershed is Christensen Creek watershed. This watershed has low impervious surface area and large blocks of undeveloped old-growth forest and it shows! A large variety and abundance of stream bugs are happy here including many sensitive species.

Our lowest scoring watershed is Ellis creek. This may be a case of poor sampling rather than actual condition. Ellis creek has a salt marsh at the mouth and for many years the sample point was located in an area with saltwater influence. This likely caused this watershed to score lower than it should have. When VNC took over this sample site we moved the site upstream. For 2 years Ellis Creek scored similar to Gorsuch creek "poor" but not "very poor". After that a beaver moved in! This flooded the entire lower section of creek making it a pond rather than a stream. This is great for fish habitat and water retention and will likely improve health of the saltmarsh. But, B-IBI, designed for moving streams, is no longer a good sampling design for this creek. Our best assessment from the two years of appropriate sampling is that Ellis creek is in poor but not very poor condition, likely due to the high amount of impervious surface area in the watershed leading to erosion, scouring and sedimentation.

Most creeks sampled are scoring in fair condition and all creeks sampled are either steady or improving over their sampling periods. This is good news that none of the creeks sampled are declining in health over the sampling period. Congratulations to islanders for helping bend the curve in a positive direction!

No creeks sampled were in excellent condition. This is a good challenge for us to see if we can get any watersheds to this level.

Which watershed do you live in? Has your neighborhood stream been sampled?

Three Top Take Homes from Stream Bug Stories

Stream invertebrates have given us the following lessons that are generally applicable to creeks island wide.

Lesson 1: Impervious surface matters

Map of impervious surface area in each island watershed.

Even in small amounts impervious surface can degrade stream health.

We have 111 drainage basins on Vashon. Not all of these have creeks. Some are dry areas that drain to the Sound in storms. 70 contain creeks.

 New EPA research points to measurable impacts on watershed health starting with impervious surface areas as low as 4% . 35% of watersheds on Vashon have impervious surface areas above 4% indicating that they could be experiencing impacts from stormwater runoff.

16 watersheds are approaching 4% (with over 3% impervious surface area) indicating that they are close to the threshold and could cross it in the next few years.

Gorsuch Creek has the most impervious surface area of any watershed on Vashon at 19 %.

Of the streams sampled for Benthic Index of Biotic Integrity, those with the highest impervious surface areas exhibited the most impacted Benthic Index of Biotic Integrity scores.

B-IBI scores: 0-20 is very poor condition; 21-40 is poor condition; 41-60 is fair condition; 60-80 is good condition; 80-100 is excellent condition.

Even very low impervious surface areas have an impact on B-IBI scores. Only one of our creeks has an average B-IBI score above 60 which indicates good condition. And all watersheds sampled that have impervious surfaces over 6% had poor Biotic integrity levels.

How can you help reduce stormwater impacts in your watershed?

Plant trees, minimize impervious surfaces, and store stormwater runoff from impervious surfaces on your property. Create rain gardens or swales to help slow down run off and let it sink into our aquifer. All of these actions can increase the resilience of your watershed and help increase or maintain biological integrity.

In addition, considering that climate change predictions call for heavier rainfall events in winters, all of the above actions will help our watersheds and aquifers maintain resilience to these more intense storms. If we can increase the storage capacity of our surfaces and soils we will increase the capacity of the land to soak in rainfall and deliver it to our aquifers rather than letting it run into the Puget Sound.

Water Wellness Take-Homes

Lesson 2: Restoration activities appear to be working!

Judd Creek log restoration

A comparison of B-IBI scores before and after log restoration efforts in Judd Creek shows that there is a statistically significant improvement in Benthic Index of Biotic Integrity scores after log restoration projects have been put in place (t-test assuming unequal variances: p=.0012, df=17).

The adjacent graph shows B-IBI scores in Judd Creek from 2002 to present along with years where log restoration was conducted. This is an observational long-term monitoring study rather than an experimental study so we can only infer these results based on the correlation of the scores to the restoration actions.

The challenge of Shinglemill

In some creeks restoration is more challenging and takes longer time periods to increase B-IBI scores. There was no statistically significant difference between B-IBI scores before and after log replacements (2007-2008) in Shinglemill creek (t-test assuming unequal variances, p=.062, df=20).

However, scores were significantly higher in 2013-2021 compared to previous years (t-test, p=.006, df=11). The most recent sediment control measure in Shinglemill which helped control sediment and erosion from the Needle Creek nick point was completed in 2012 and the car wash kits were installed in 2014. Both of these actions directly aligned in time with measured improvements in B-IBI scores.

Is this improvement due to the most recent actions or is it the result of the accumulated effort of a variety of restoration efforts over this longer time period? It is impossible to say with the information we have.

But two things are clear: Shinglemill scores have improved since 2013 and it took more restoration effort to start increasing scores in this watershed compared to Judd Creek.

Shinglemill watershed has much steeper slopes than Judd Creek and more impervious surface area. This likely makes it more vulnerable to impacts from stormwater runoff. And, this higher vulnerability likely means that it takes more restoration attention and effort to keep this watershed intact and healthy. It is more sensitive to impacts due to its steep nature. This will also likely make this watershed more sensitive to higher intensity storms predicted in climate change models. Therefore, we recommend continuing a concerted and multi-faceted effort to tackle stormwater issues throughout this watershed.

Lesson 3: We can help increase the resilience of our watersheds to climate change.

Islanders of all generations are helping us monitor our creeks on Vashon. Together they have generated important information through stream invertebrate surveys that can help us responsibly manage for water wellness in the face of climate change.

You can help steward our watersheds

  • Minimize impervious surface where possible: many of the impacts predicted by climate change models are worsened by impervious surface.
  • Slow down waterflow to help safeguard streams as storms become more intense. If you live in the Vashon Sewer District you can get a free consultation on slowing stormwater flows on your property by contacting islander Michael Laurie: mlaurie@mindspring.com. Another good resource is  King County Stormwater Service s or  12000 Rain Gardens in Puget Sound .
  • Plant trees! Trees shade streams decreasing heat impacts in summer. They also help slow stormwater runoff in winter. And, they sequester carbon! And, some people enjoy hugging them. Yay for trees.
  • Support policies and actions that slow or stop climate change on a broad scale. Some things we cannot do anything about locally. For example, the timing of rainfall is predicted to shift to a later start in the fall. This will make it hard on salmon that require rain to enter our creeks during their fall spawning runs. Encouraging policy changes and actions to stop global warming on a large scale will help minimize changes to large scale climate shifts that impact watershed health.
  • Mind the Clingers! These stream bugs cling to rocks and get washed out in large storms. Clingers were particularly low in samples from the following watersheds indicating these watersheds may be most vulnerable to increasing stormwater flows: Shinglemill, Gorsuch, Ellis, McCormick, and some stretches of Judd. These creeks are priority areas for decreasing stormwater flows to increase resilience to climate change.
  • Mind the Mayflies and Blackflies! Some species of mayflies and blackflies increase with nutrient enrichment. The proportion of blackflies also increases in a stream sample as stream temperatures rise. Watersheds that had higher levels of blackflies and higher proportions of some mayfly species are predicted to be most vulnerable to heat and nutrient-enrichment: Ellis, Judd, Gorsuch, Christensen (nutrients but not heat). Planting trees in these watersheds and decreasing sources of nutrients (from animal manure to fertilizers--even organic, to septic leaks) would help increase the resilience of these watersheds to expected climate impacts.

We humbly thank the many hundreds of volunteers ages 8 to 80 as well as all the wondrous and beautiful stream bugs in our creeks. You have all helped us collect the information presented here that can guide us in responsibly safeguarding our freshwaters together into the future.

Acknowledgements

Thank you to the Rose Foundation, King County Waterworks program, Vashon Schools Foundation, PIE, B-WET, and Vashon-Maury Groundwater Protection program for supporting this effort. Thank you to Susie Fitzhugh, Jeff Adams, and Bianca Perla for photography. Thank you to Gay Roselle and Charlie Ralston for leading your students in contributing to community science in the creeks. Thank you to Rhithron Labs in Montana for analyzing our stream invertebrate samples each year. Thank you to all who reviewed this document. Thank you stream bugs. Thank you to the people of Vashon who volunteered their time to come to the creeks with us to take this data and who help on planting crews. And thanks to all who care for their properties in a way that safeguards our precious water sources.

Stream bugs like this little stonefly from Shinglemill Creek, can tell us a lot about how our stream are faring and what we can do to help them stay healthy.

Island watersheds sampled for stream invertebrates. Entire sampling period spans from 2000-2022 but is shorter for some creeks. Average Benthic Index of Biotic Integrity Score (B-IBI) over all sample years is shown in corresponding color. Raw data can be found at pugetsoundstreambenthos.org

Islanders of all generations are helping us monitor our creeks on Vashon. Together they have generated important information through stream invertebrate surveys that can help us responsibly manage for water wellness in the face of climate change.