Around the Water Cooler

Dec 2, 2015

Lungs of the Sea

Around the Water Cooler, coastal ecosystems, environment, water, Water Quality 1 Comment

As a diver and marine biologist for EPA, I spend a fair amount of time underwater. My area of expertise is in the study and conservation of seagrass. These underwater meadows can cover vast swaths of the seafloor and they serve as important nurseries for many fish and shellfish species.

Recently, I had the great fortune of taking a family trip to France and spending some time along the southern coast. It was my first visit to the Mediterranean Sea and I was looking forward to exploring the underwater realm. We stopped in the small town of Cassis, which reminded us of Gloucester, Mass. Cassis has its own fisherman’s statue. It does not have a greasy pole to climb like Gloucester, but it does have its own unique tradition. Local fishermen mount planks on the back of two dories. Boys of about 10 years old are lifted up onto the planks wearing pads on their chests and are given lances. The boats then drive directly at each other and the boys joust until one or both fall into the water.

The local culture was interesting, but Cassis is also known for “les calanques.” Calanques are inlets surrounded on three sides by steep cliffs; they also are known as mini-fjords. Within these inlets, seagrass flourishes in the clean, calm protected waters. The French refer to seagrass as “les poumons de la mer,” which translates to the lungs of the sea. Like all plants, seagrasses produce oxygen through photosynthesis. On sunny days, it is common to see bubbles of oxygen being released from the leaves of seagrass into the water.

In Cassis, protecting seagrass is taken very seriously with a variety of rules. Boaters are not allowed to anchor or place a mooring in seagrass meadows. Boaters are required to stay in the marked navigation channels and when in shallow water reduce their speed so no wakes are produced. In our three days in Cassis, we watched many boats come and go, and not one of them broke the rules.

I approached one of the local fishermen and with my limited French asked him about the local seagrass meadows. He spoke little English. I spied a shoot of seagrass floating near his boat. He scooped it up and held it close to his heart and said “les poumons de la mer.”

We didn’t speak the same language, but our common love of the ocean easily transcended the language barrier.

More information on EPA Seagrass research: http://www2.epa.gov/sciencematters/epa-science-matters-newsletter-how-deep-are-seagrasses

Connect with EPA New England on Facebook: facebook.com/EPARegion1

Connect with EPA Divers on Facebook: facebook.com/EPADivers

About the author: Phil Colarusso is a marine biologist in the Coastal and Ocean Protection Section of EPA’s New England office, and is an avid diver.

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Jul 23, 2015

Experience history and nature on rail-trails

Around the Water Cooler, Chesapeake Bay, In Your Backyard, outdoor activities, Stormwater, urban escapes 1 Comment

by Virginia Thompson

A view from the Heritage Rail Trail County Park.

My husband is a huge fan of biking on rail-trails created by the conversion of unused railroad rights-of-way. Within the past year alone, he has ridden on many trails in the Philadelphia suburbs, as well as throughout the Mid-Atlantic states. On a recent trip, we rode on two rail-trails in southcentral Pennsylvania.

The Heritage Rail Trail County Park in York County, recently ranked by the Rails-to-Trails Conservancy as the top rail-trail in the U.S. for American history, carried President Abraham Lincoln to Gettysburg for his famous address and also carried his funeral party to Springfield, Illinois, following his assassination. The trail follows the South Branch of Codorus Creek, connecting the City of York and many small communities with beautifully restored train stations that now serve other purposes. The trail, next to an active rail line, also continues across the Mason-Dixon line and connects with the Northern Central Rail Trail in Maryland.

The Safe Harbor Dam as seen from the Enola Low-Grade Trail

Another trail we biked recently was in Lancaster County—the Enola Low-Grade Trail—which parallels the Susquehanna River as it approaches the Chesapeake Bay in Maryland. One of the interesting facets of the trail is the juxtaposition of older and new forms of electric power. On the cliffs above the trail are several large windmills, taking advantage of the height and open space to generate electricity. Just below the windmills sits the Safe Harbor dam, reliably providing hydroelectric power since December 1931. The fish congregating at the dam attract bald eagles, which can be seen flying above the dam. There’s nothing quite like experiencing history and nature by biking or hiking a rail-trail. At one stop on the trail, as I looked up at the windmills and down to the river and generating station, I felt small and insignificant in one respect, but also an important part of the natural balance.

Turning formerly used rail lines into biking and hiking trails is a great way to bring people closer to waterways in their regions. EPA’s Brownfields program has had a hand in converting unused rail lines, which often snake along picturesque rivers (our nation’s original highways), into prime recreational areas. The Harrison Township Mine Site in Allegheny County, Pennsylvania was assessed through a Brownfields grant, and is now part of the Rachel Carson trail, attracting area visitors as well as hiking and running events. Allegheny County is even acquiring additional land so that the Harrison Hills Park Mine Site will ultimately connect three trails – the Rachel Carson Trail, the Butler-Freeport Trail, and the Baker Trail.

Leave a comment below to let us know about rail-trails in your area.

About the author: Virginia Thompson works at EPA Region 3 and accompanies her husband on his rail-trail adventures as often as possible.

Jun 26, 2015

Summer Reading List: Learn About States’ Shapes, Social Physics, and Rust

Around the Water Cooler, Education, In Your Backyard 1 Comment

By Jeffery Robichaud

I was in Seattle for a meeting this spring and realized that my kids had only two more weeks before they were off for the summer. My wife and I would face the yearly struggle of convincing them to read for “fun” again. It was also a reminder that I needed to build my reading list for the summer!

So here’s my Big Blue Thread Summer Reading List for 2015. While you’re at it, check out my Fall 2012 Reading List and Fall 2008 Reading List.

“How the States Got Their Shapes” by Mark Stein

This book has been out for a while but I picked up the paperback version for my kids at the Smithsonian earlier this year. I intended for them to read it, but I ended up being the first to crack it open. It is chock-full of the stories behind all the minor squiggles, curves, and not-so-straight lines that make up our states’ borders. If you find yourself bored at home sometime, pull up Google Maps and zoom in really, really close, and you may find that many of the straight lines you learned as a child aren’t so straight after all. There appears to be a second book from Mark Stein called “How the States Got Their Shapes Too: The People Behind the Borderlines.” If you’ve read it, jot down a comment below and tell me how it was.

“Social Physics: How Good Ideas Spread – The Lessons from a New Science” by Alex Pentland

I’m not entirely done with this book yet. It’s beckoning me from the nightstand, competing with all the shows that my wife and I have stored on our DVR. So far, this has been a really interesting read, focusing on the importance of social interaction in creativity and innovation in the workplace. It puts a lot of things into perspective with respect to the new “connected” workforce, or more accurately, how we might be missing some really great opportunities because of the lack of meaningful social interaction and stimulation. Definitely a headier read, so if you have little ones who will be vying for your attention, save it for another time.

“Rust: The Longest War” by Jonathon Waldman

OK, I’ve only made it through the first few chapters of this book, and I really enjoy it. I’m going to save the rest for the beach later this year (especially since saltwater plays a prominent role). If you enjoyed other historical treatises such as “Salt,” “Water,” or “Cod” (I sense a theme), then I’m pretty sure you will enjoy “Rust.” The writing is fast-paced and funny. Waldman tells us, “rust affects everything from the design of our currency to the composition of our tap water, and it will determine the legacy we leave on this planet.”

So head out and pick up a new book for the summer. Better yet, support your local library with a visit. While you’re there, ask them how to sign up to check out e-books and audiobooks. After your visit, share some of your recent reads with us. What page-turner would you recommend we pick up this summer?

About the Author: Jeffery Robichaud is a second-generation EPA scientist who has worked for the Agency since 1998. He currently serves as Deputy Director of EPA Region 7′s Water, Wetlands, and Pesticides Division. Jeffery fondly remembers card catalogs from his youth and wonders what became of all those beautiful old wooden shelves. (Youngsters who have no idea what he’s talking about should check out the opening scene in “Ghostbusters.”)

Aug 12, 2014

EPA Science In Action: Keeping an Eye on Harmful Algal Blooms

Around the Water Cooler, blue-green algae, cyanobacteria, drinking water, harmful algal bloom, microcystin, Ohio, Toledo, Water Treatment 6 Comments

By Cindy Sonich-Mullin

A half million people living in and around Toledo, Ohio recently experienced a weekend without tap water. A “harmful algal bloom” of cyanobacteria in Lake Erie, Toledo’s water source, produced unsafe levels of the toxin microcystin. The toxin is known to cause abdominal pain, nausea, vomiting, and at high exposure levels, liver damage.

A water advisory was issued alerting residents to avoid all contact with Toledo drinking water.

At the first sign of trouble, colleagues at the Ohio Environmental Protection Agency contacted my laboratory to provide technical assistance and water sample analysis to support the City of Toledo’s drinking water utility.

We were a natural choice to help out. Not only is EPA’s Cincinnati-based laboratory facility relatively close geographically, but our scientific staff includes a team of leading experts with analytical capabilities in drinking water treatment and cyanobacterial toxins.

Throughout the weekend, we performed tests and conducted sensitive analyses to help identify the optimal approach for controlling the toxins in Toledo’s water plant and distribution system. We shared our test results with our partners from Ohio EPA, who interpreted them along with their own results and others from the City of Toledo.

We were all greatly relieved the morning of August 6^th, when the City of Toledo determined that they could lift the water advisory.

At the time, Ohio EPA Director Craig Butler released the following statement: “After exhaustive testing, analysis and discussions between Toledo water officials, the U.S. EPA and the Ohio EPA, we support the city’s decision to lift its drinking water advisory. Throughout the difficulty of the past few days everyone involved has demonstrated the utmost professionalism and commitment to solving this problem. The mayor and his team, U.S. EPA and the other scientific and academic leaders who lent us their expertise worked in a constructive way to turn the water back on for the people of Toledo.”

While many weekend plans were cancelled due to the crisis in Toledo, we were honored to be called on to help our sister city to the north. As scientists, it is gratifying to use our expertise and the tools we develop to provide solutions to communities. Of course, what would be even better than lending our expertise and rapid response and analysis capabilities would be to help prevent harmful algal blooms from threatening drinking water supplies in the first place. And that is just what we are doing. In fact, we’ve shared some of our harmful algal bloom research recently here on our blog. Below are some recent posts with more information on that work.

As the above blogs exemplify, EPA researchers are working hard to better understand the dynamics of harmful algal blooms. EPA is also working with other agencies to accelerate the development and deployment of affordable sensors that will help predict future algal blooms. This means we will be even better poised to work with cities like Toledo and other local communities to better protect precious drinking water supplies. Keep an eye here on “It All Starts with Science” to see future posts about that work, and more.

About the Author: Cindy Sonich-Mullin is the Director of EPA’s National Risk Management Research Laboratory in Cincinnati, Ohio. She has over 30 years of experience in EPA, leading research and response efforts on a wide variety of environmental issues.

Jul 31, 2014

Modeling Fish on the Move

Around the Water Cooler, carry capacity, Chinook salmon, climate change, fish assemblages, modeling, northern pikeminnow, salmon, water pollution, Willamette 5 Comments

By: Marguerite Huber

How many places have you lived? Why did you move? Personally, I have lived in eight different places because of school and jobs. Other people move to find better opportunities, like housing or a place to raise their children.

Fish are sometimes forced to move as well. But, unlike you and I, fish cannot just get up and move across towns, states, and countries. They have to move across their own river networks to maximize survival.

For fish, the availability of sufficient spawning and rearing habitats can strongly influence the productivity of an entire river network. Fish also move based on certain environmental drivers like warming temperatures, and human activities such as land development, building of dams, and changes in stream channels, which can contribute to water pollution or alter fish habitat. Additionally, fish are affected by their interactions with other species. When different species interact, they can compete for resources or have a predator-prey relationship.

The Willamette river network, color-coded to show which of the 3 primary environmental conditions are currently most limiting habitat suitability for Chinook salmon, a species of high management concern.

To fully understand fish in their changing environment, EPA researchers created a model that simulates groups of fish in river landscapes. This model helps determine how fish populations reproduce, move, and survive in response to both environmental drivers and species interactions. It is designed to help EPA assess the impacts of land development on fish assemblages, and better understand how these impacts may be intensified by climate change.

The researchers studied how Chinook salmon (Oncorhynchus tshawytscha) respond to steepness of the stream channel, flow, and temperature in the Willamette River basin of Oregon. This region is important to study because it is expected to experience substantial rises in human population and water demand over the next 50 years. The model, which can be applied to any watershed, helped create a map of the salmon’s abundance and distribution in the Willamette River basin. To capture species interaction, scientists also modeled the abundance of another fish, the northern pikeminnow (Ptychocheilus oregonensis), a native predator and competitor of Chinook salmon.

Afterwards, researchers modeled both species together, accounting for projected effects of competition and predation. They found that species interactions and temperature affect both Chinook salmon and northern pikeminnow. The results show species distributions throughout the basin and their projected responses to future stressors such as climate change, water consumption, and hydropower management.

Not only will EPA’s model help construct a map of fish on the move, but it will help inform the science used to develop water quality regulations and trading, help prioritize restoration, and advise management decisions.

About the Author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team

Jul 10, 2014

I’ll Trade You: Water Quality Science Edition

Around the Water Cooler, Chesapeake Bay, Nutrients, Nutrients Management, TMDL, Total Maximum Daily Load 0 Comments

By Marguerite Huber

Chesapeake Bay watershed includes six states and the District of Columbia. Image: NASA/Goddard Space Flight Center Scientific Visualization Studio

The outcome of a trade can sometimes be the luck of the draw. You may not have gotten a better sandwich for the one you traded at lunch, or the all-star pitcher your team acquired in that mid-season trade may turn out to be a bust.

On the other hand, the best kind of trade is one where everybody wins. EPA researchers are helping bring just that kind of trade to improve water quality.

Chesapeake Bay is an expansive watershed that encompasses some or all of six states and the District of Columbia. High levels of nutrients flowing in from all over that expansive watershed decrease oxygen in the water and kill aquatic life, creating chronic and well-known dead zones.

To help, EPA established the Chesapeake Bay Total Maximum Daily Load (TMDL), which sets a cap on nutrient and sediment emissions to restore water quality, ensure high quality habitats for aquatic organisms, and protect and sustain fisheries, recreation and other important Bay activities.

Recent innovations in Chesapeake Bay and elsewhere have promoted a new type of trading, called water quality trading, to meet watershed-level reductions in nutrient pollution. The goal is to facilitate individual flexibility and responsiveness while creating incentives to reduce overall nutrient flow from both agricultural and urban areas.

Here is how water quality trading would work…

Farmers and wastewater treatment plants have the opportunity to team up to collectively meet the water quality goal by reducing nutrients. While both entities have their own baseline nutrient emission level they must shoot for, they can gain tradable credits if they do better. A farmer that plants nitrogen-absorbing crops such as barley and wheat can sell the credits they gain to a wastewater treatment plant that needs to reduce its own emissions.

A healthy Chesapeake is a win for everybody!

Trading is based on the widely different costs it can take to control the same kind of pollutant, depending on its source and location. For example, upgrading wastewater treatment plants and ripping up urban streets to replace leaky stormwater drainage pipes could cost billions of dollars. On the other hand, planting new or different crops is much less expensive.

Like the TMDL itself, the development of the water trading system began with science. EPA-supported scientists and economists developed a computer model to find the least costly mix of pollution-reduction options across the watershed for meeting the TMDL. The model also has been used to explore how different trading policies could help to meet TMDL requirements, and as the basis for analyzing policies leading to the nutrient trading guidelines for Chesapeake Bay.

Overall, water quality trading depends on cooperation across the watershed to help achieve faster, less expensive pollutant reductions that improve the Bay’s water quality. It’s a win-win for everybody.

About the Author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team.

Jun 26, 2014

Modeling Cyanobacteria Ecology to Keep Harmful Algal Blooms at Bay

Around the Water Cooler, chlorophyll a, Citizen science, cyanobacteria, ecological modeling, harmful algal blooms, Nutrients, pigments, U.S. Army Corp of Engineers, Watershed Watch 3 Comments

By: Betty Kreakie, Jeff Hollister, and Bryan Milstead

Sign on beach warning of harmful algal bloom

U.S. Geological Survey/photo by Dr. Jennifer L. Graham

Despite a lengthy history of research on cyanobacteria, many important questions about this diverse group of aquatic, photosynthetic “blue-green algae” remain unanswered. For example, how can we more accurately predict cyanobacteria blooms in freshwater systems? Which lakes have elevated risks for such blooms? And what characteristics mark areas with high risks for cyanobacteria blooms?

These are important questions, and our ecological modeling work is moving us closer to finding some answers.

The gold standard for understanding cyanobacteria in lakes is direct measurements of certain water quality variables, such as levels of nutrients, chlorophyll a, and pigments. This of course requires the ability to take on site (“in situ”) samples, something that is not possible to do for every lake in the country. Our modeling work is focused on predicting cyanobacterial bloom risk for lakes that have not been directly sampled.

We are using remote sensing and geographic information systems (GIS) data to model bloom risk for all lakes in the continental United States. The work is also starting to shed light on some of the landscape factors that may contribute to elevated predicted bloom risk. For example, we know that different regions have different predictive risk. We are also learning about how lake depth and volume, as well as the surrounding land use impact cyanobacteria abundance.

In addition to our national modeling efforts, we are collaborating with others on smaller scale and more focused studies at regional and local scales. First, we are partnering with other EPA researchers to develop time-series models using data gathered frequently and over a long time by the U.S. Army Corp of Engineers. By using these data, we expect to tease apart information about annual timing and the intensity of blooms. We can also explore aspects of seasonal variability and frequency. Lastly, we are starting to explore ways to use approximately 25 years of data collected by Rhode Island citizen science as part of the University of Rhode Island’s Watershed Watch program. We hope to mine these data and uncover indicators of harmful algal bloom events.

With all this work, we and our partners are adding new chapters to the long history of cyanobacteria research in ways we hope will help communities better predict, reduce, and respond to harmful blooms.

About the Authors: EPA ecologists Betty Kreakie, Jeff Hollister, and Bryan Milstead are looking for ways to decrease the negative impacts of cyanobacteria and harmful algal blooms on human health and the environment.

NOTE: Join Betty Kreakie, Jeff Hollister, and Bryan Milstead for a Twitter chat today (June 26) at 2:00pm (eastern time zone) using the hashtag #greenwater. Please follow us @EPAresearch.

Jun 25, 2014

Tool Saves Millions of Dollars After Wildfire

Agricultural Research Service, AGWA, Around the Water Cooler, EPA Landscape Ecology, USDA, Watershed, wildfire 3 Comments

By Marguerite Huber

Wildfire conflagration on forested hillsides

Wildfire seasons are getting longer and burning more acres. Photo by USDA Forest Service.

Fueled by drought, disease, and suburban sprawl, wildfire seasons are getting longer and burning more acres of land. Last August, the Elk Complex wildfire burned more than 130,000 acres east of Boise, Idaho. Nearly 75% of the burned area had high to moderate burn severity, threatening the ecosystem and the region’s water. Substantial fires have already flared up this summer around San Diego, California, and Flagstaff, Arizona.

Once a fire is about 80% contained, scientists and other experts from the Department of the Interior’s National Interagency Burn Area Emergency Response (BAER) team can go into the region and help develop emergency stabilization plans. They are aided by a resource—the Automated Geospatial Watershed Assessment (AGWA) tool—developed by researchers from EPA, the Agricultural Research Service (part of the U.S. Department of Agriculture), and the University of Arizona.

Originally developed as a computer model for use managing and analyzing water quantity and quality, fire recovery teams are now tapping it to identify potential threats to people, wildlife, and the land from post-fire flooding and erosion.

Watershed managers use AGWA to identify and assess downstream impacts and risks from increased flooding and erosion resulting from fire-related changes to habitats and soils. The tool can also be used to target restoration efforts, such as where to apply mulch and seed with native plant stock, to reduce such downstream risks.

“AGWA is a good example of a science product developed between two leading federal research agencies with mutual interest,” said EPA research ecologist William Kepner. “The tool provides a practical application with immediate benefits.”

For the Elk Complex wildfire, the BAER team estimates it saved approximately $7,000,000 to $8,000,000 by using AGWA to target 2,000 acres for treatment instead of the initial 16,000 acres identified through more traditional methods.

“AGWA is able to help the team develop a stabilization plan where post-wildfire impacts pose immediate and significant threats to people and property,” Kepner adds.

Additionally, the emergency response team has successfully used the tool for post-fire watershed assessments following fires in Arizona, New Mexico, California, Idaho, and Washington. More than 8,000 users, spanning six continents, 163 countries, and 4,903 cities, have registered to use the Automated Geospatial Watershed Assessment tool .

The AGWA tool has been included as an ecosystem services analysis tool in the new EPA EnviroAtlas, and can be downloaded here. It provides an important resource for meeting the challenge of longer, more destructive wildfire seasons.

About the Author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team.

Jun 23, 2014

Open Science and Cyanobacterial Research at EPA

Application Programming Interfaces, Around the Water Cooler, cyanobacteria, EPA National Lakes Assessment, EPA Water Research, EPA's Environmental Dataset Gateway, harmful algal blooms, microcystin, Open Science, PLOS One, SPARROW model 0 Comments

By: Jeff Hollister, Betty Kreakie, and Bryan Milstead

Algal bloom containing cyanobacteria.

It wasn’t long ago that science always occurred along a well-worn path. Observations led to hypotheses; hypotheses led to data collection; data led to analyses; and analyses led to publications. And along this path, data, hypotheses, and analyses were held close and, more often than not, the only public-facing view of the research was the final publication.

Science has come a long way with this model. However, it was conceived when print was the main media and most scientific questions could be investigated by few scientists over a short period of time.

Then came computers. Then came the internet.

Just like in every other aspect of modern life, these advances are greatly impacting science. It has changed who conducts our science, how we share it, and how others interact with scientific information. All of these changes are playing out through the increasing openness of all parts of the scientific process.

This broad area has been defined as having several components. These components suggest that “open science”:

is transparent (and, of course, open)
includes all parts of research (data, code, etc.)
allows others to repeat the work
should be posted on an open and accessible website (while protecting Personally Identifiable Information, etc.)
occurs along a gradient (i.e. not just a binary open vs. not open)

At EPA, we are learning how to make our research on cyanobacteria and human health (for more info join our webinar) meet those criteria. We are implementing open science in three ways: (1) making our work available via open access publishing; (2) providing access to the code used in our analysis; and (3) making our data openly available.

Several members of our research group have embraced open access options for publishing their research. For instance, our colleague Elizabeth Hilborn and her co-authors published results of their study—examining a group of dialysis patients following exposure to the cyanobacteria toxin microcystin—in one of the pioneering open access journals, PLoS ONE. Also in PLoS ONE, EPA scientist Bryan Milstead and his collaborators published a modeling method to combine the U.S. Geological Survey’s SPARROW model (a modeling tool for interpreting regional water-quality monitoring data), lake depth, lake volume, and EPA National Lakes Assessment data to estimate nutrient concentrations.

As our work progresses, we will continue to choose open access journals. In our experience, this has allowed our research to reach a larger audience and we can more easily track the impact through readership levels using available tools such as PLoS Article Level Metrics.

We are also sharing our data. Currently, this is accomplished through supplements added to publications and through sites such as the EPA’s Environmental Dataset Gateway. We plan to expand these efforts via data publications, version-controlled repositories, and through the development of Application Programming Interfaces (APIs) that provide access to data for developers and other scientists.

The goal of these efforts, and more (stay tuned for a future post on how coding fits in to open science), is to increase the reproducibility of our work (but challenges remain), reach broader audiences, and eventually have a greater impact on our understanding and management of harmful algal blooms.

About the Authors: EPA ecologists Jeff Hollister, Betty Kreakie and Bryan Milstead study greenwater for a living. If you have questions for them, join the webinar on June 25^th or follow the twitter chat on June 26^th using #greenwater.

Jun 19, 2014

Wetlands: Earth’s Kidneys

Around the Water Cooler, nitrogen, Nutrients, oxbow, phosphorous, stormwater management, watershed management, wetlands 2 Comments

By Marguerite Huber

Stream restoration research

Our organs are vital to our health, with each one playing a significant part. Kidneys, for instance, filter our blood to remove waste and fluid. Wetlands are often referred to as “Earth’s kidneys” because they provide the same functions, absorbing wastes such as nitrogen and phosphorous. When excess amounts of these substances—nutrient loading—flow into waterways it can mean harmful algal blooms, hypoxia, and summer fish kills.

Recognizing the importance of wetlands, many communities are taking steps to protect, restore, and even create wetlands.

For example, many stream restoration projects include constructing wetlands to absorb stormwater runoff and absorb excess nutrients and other pollutants that flow in from a host of sources across the watershed (known collectively as nonpoint source pollutants).

These constructed wetlands can provide key elements to urban stormwater management because they help reduce the impacts of runoff after a rainstorm or big snowmelt event. Such runoff typically transports high concentrations of nitrogen and phosphorous and suspended solids from road surfaces into waterways.

One such type of wetland that may provide these kinds of benefits is the oxbow lake, so named because of their curved shape. These form naturally when a wide bend in a stream gets cut off from the main channel, but EPA researchers are taking advantage of a couple of oxbow wetlands created during stream restoration activities at Minebank Run, an urban stream in Baltimore County, MD.

The researchers are studying the oxbow wetlands to quantify how effective such artificially created wetlands are at absorbing nitrogen and phosphorous in an urban setting. If these types of wetlands are effective, then deliberately constructing oxbow wetlands could be an important nutrient management strategy in such landscapes.

From May 2008 through June 2009, the researchers analyzed water, nitrate (a form of nitrogen pollution), and phosphate flow during four storms to better understand the impacts of hydrology on the potential for the two oxbow wetlands and the adjacent restored streambed to absorb or release nutrients.

The results suggest that oxbow wetlands in urban watersheds have the potential to be “sinks” that absorb and store nitrogen. They also reinforced information pointing to the dynamic hydrologic connection linking water and nutrient flow between streams and nearby oxbow wetlands, findings that if confirmed through further investigation can be used to improve restoration efforts that improve water quality across entire watersheds.

When it comes to phosphorus, the researchers found that oxbows don’t function as “sinks,” but “sources,” that contribute a net increase of the nutrient. They hypothesize that this is because the nutrient is released from wetland sediments during storms or other similar events. Future studies are needed to investigate the magnitude of phosphorous release, and how important that contribution is across the watershed.

Just like how our kidneys are an essential aspect of the human body, wetlands are an important aspect of nature. Retaining additional nutrients and treating non-point source pollutants help give natural and constructed wetlands the affectionate nickname of “Earth’s Kidneys.”

About the Author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team.

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