Arlington Is Going Sunny Side Up

The world is changing. Increasingly, cities are trying to work with nature to create systems that more closely reflect natural systems. Stormwater is being infiltrated to recharge groundwater, solid waste is recycled or burned to generate power for 20,000 homes annually and roof-top solar panels are increasingly providing electricity for Arlingtonians.

Workers installing solar panels

What could be more natural, Arlington, than using the sun? Solar power has been the energy source of the future for decades and we’ve been waiting for solar panels to make the one last technological breakthrough that makes it cost-competitive. It’s always been a few years away.

Stop for a second and think about not having an electric bill or having a very minimal electric bill. That sounds nice, right? Wait no longer, folks. Solar is here. 

Arlington Initiative to Rethink Energy is partnering with the Potomac Solar Co-Op to offer residents a 20-30% discount on solar panels for your home. Last year, the Rethink Energy team helped 34 homeowners put solar on their roof through the co-op. That effort helped increase the number of solar systems by 42%.

32 Arlington homeowners installed solar with the last co-op42% increase in number of solar systems in Arlington since the last co-op

Solar has never been more affordable. The price of solar has dropped by about 50% over the last decade. Depending on the size of your home, you may be able to put solar panels on your roof to generate most, if not all, of the electricity you use in your home. Prices are less than $10,000 after co-op discounts and federal tax credits. This provides you with clean energy and significantly reduces your energy bills for many years to come.

chart showing the decrease in solar panel costs over the years

If you’re interested in joining, sign up on the co-op website. This allows VA SUN to screen your roof virtually, and they’ll keep you posted on next steps. There’s no obligation until you sign a contract.

The Journey of the American Eel

American Eel

American Eel. Source:

The only fish you are likely to find in Arlington’s Gulf Branch is the American Eel. This has little to do with the water quality of Gulf Branch and more to do with heavy runoff after rains. The scouring action of rushing water after a storm makes it difficult for fish populations to maintain a foothold (or fin-hold) in the stream. Other streams in Arlington, such as Four Mile Run and Donaldson Run, also have eels, but Gulf Branch is probably the only one where the eels are the only fish you will encounter. This is also a result of the large, steep, rocky waterfall where Gulf Branch dumps into the Potomac, which acts as a barrier to most fish moving upstream. However, one could not ask for a more interesting or unusual fish to be found in Gulf Branch.

American Eels (Anguilla rostrata) have small pectoral fins and long, continuous dorsal and anal fins. Their long, slender bodies look far more snake-like than fish-like. A layer of mucus covers the eel’s skin, and its scales are small and well embedded in its epidermis, making them hard to see. The eel itself may also be hard to spot as they are typically nocturnal. American Eels are a generalist species as a result of their life cycle, and they can survive in a variety of freshwater different habitats including streams, rivers, lakes, estuaries and coastal bays. Their diet is just as varied and includes most aquatic organisms, living or dead, found in any habitat they may occupy.


Eel in its natural habitat

The life cycle of the American Eel is an amazing story that spans miles and decades. These fish are catadromous, meaning they migrate from freshwater to the ocean to spawn. These eels hatch in the Sargasso Sea as small, nearly transparent and flattened larvae that look quite different from adults. The larvae begin a long, passive migration as currents guide them to the coastal waters of Eastern North America over the course of seven to twelve months.

Eels go through several morphological changes as they grow. As the eels grow larger and approach their new freshwater homes, they begin to produce pigment and darken in color. While their transparency made them difficult to spot drifting in currents along the open ocean, this new darker color provides camouflage against the dirt and rocks at the bottom of estuaries and rivers.

While most fish get flushed out as a result of stormwater in Gulf Branch, eels are accomplished, upstream swimmers. Natural barriers like waterfalls, and even human-made barriers such as smaller dams, are not always enough to stop the upstream migration of eels. Eels have been reported moving across short distances on land in wet or rainy conditions to get around waterfalls or dams. American Eels have been spotted in Gulf Branch upstream beyond Military Road. Their elongate body also helps them find shelter in cracks and openings too small ornarrow for larger fish.

Here they may spend 10-25 years maturing before beginning the return journey to the Sargasso Sea. As their body gets ready for the long journey, their pectoral fins enlarge for better swimming capability, their eyes enlarge to adapt to the oceanic environment, and their skin thickens to protect against the saline environment.

American Eels are semelparous. This reproductive strategy is also called “big bang” reproduction because it happens once, in a large quantity and is typically fatal. Female eels may produce 400,000-2,500,000 eggs. Adults die after mating and spawning in the Sargasso Sea, completing an odyssey that lasts more than a decade and covers hundreds of miles. Thankfully, the completion of their journey means the beginning of another, ensuring that Arlingtonians will continue to enjoy encountering this curious fish in our local streams.

Recovering Nature from Our Trash

While this blog is dedicated to all things natural in Arlington, today I’m going to discuss something you may think of as an unnatural aspect of human society: trash. What does trash consist of? Think about it: our trash (or discards, waste, rubbish, garbage, refuse) is made up of various natural, or biological materials, including food, metals and fibers, many of which can be recovered and reused or recycled. In fact, very little of what we use and throw away is unable to be composted, recycled or otherwise recovered. As such, a nationwide movement is afoot to reassess what we are calling “waste.” Instead of viewing trash as a waste to be managed and disposed of, many communities instead regard these discarded materials as resources to be recovered.

residential waste graphYou may have heard about the Arlington County Board adopting a Zero Waste Resolution in late 2015, which aims to divert 90 percent of wastes from landfills and incineration by 2038. Right now the County diverts about 44 percent of its waste stream from disposal. This means we still have a large amount of materials left to capture… but what are they? The figure to the left shows what was left in Arlington’s single-family residential waste stream in 2015 after accounting for the removal of recyclables.

As you can see, a large part of our trash consists of food waste and yard waste. The County is on the right track with the year-round yard waste program that was introduced in April 2016, which removes some recoverable materials. After just two months of implementation, the County collected 1,767 tons of yard waste. Over this same time period, the trash decreased by 1,930 tons! The County hopes to target food waste as the next material to remove from the waste stream. Although Arlingtonians are familiar with and supportive of recycling and composting as effective recovery practices, the County will also have to work regionally to develop additional progressive programming, facilities and technology for extracting the remaining value from our discarded materials. Most importantly, however, accomplishing waste reduction entails not generating discards in the first place.

Waste reduction is the most environmentally and cost-effective way of achieving zero waste goals. Specific environmental and economic benefits of waste reduction and resource recovery include the following:

  • Promotes sustainable resource use. Recyclable or reusable material can be used over and over again, thus limiting the use of virgin resources used in our extract-use-discard approach to producing goods.
  • Mitigates climate change impacts. The production, consumption and disposal of our goods and products is estimated to generate 42 percent of all U.S. greenhouse gas emissions. Creating goods that are easily repairable, reusable or recyclable, as well as developing a less wasteful food system, can help alleviate greenhouse gasses associated with these activities.
  • Creates green jobs and promotes local economy. Figuring out how to redesign products and their packaging for reuse and recycling takes creativity and engineering skills, while the marketing and distribution of these products entails business acumen.

Before the Fall: Appreciating Tree Leaves

After the explosion of the cherry blossoms, magnolias, serviceberries, catalpas, and other showy flowers, summer often feels like an aesthetic drought because most of the trees are done blooming. But there is a subtle beauty that will never leave you once you notice it. Young leaves coming through in mid to late spring, throughout the summer, with second flushes, and the fully formed leaves are a wonder to behold. Green is a deceptive color, as it often blends with its surroundings, but the shapes of leaves are just as diverse as flowers in their creativity.

Young leaves

Young white oak leaves

Young white oak leaves

Early emerging leaves, and leaves that come to trees as they go through multiple flushes of leaves (like black cherry (Prunus serotina), for example, whose early leaves are often defoliated by tent caterpillars) are little works of art. Oak leaves in large masses are impressive on the tree, but every large oak leaf starts out as an intense concentrated red (see the young white oak (Quercus alba) leaves on the right). These leaves have significant amounts of anthocyanins, natural chemicals that act as sunscreen, giving it the color. These colors dominate before the green chlorophyll, the pigments that help in converting sunlight into food, takes over.

Young tuliptree leaves

Young tuliptree leaves

Other leaves are fascinating for how they unfold. The cat-face-shaped Tuliptree (Liriodendron tulipifera, on the left) leaves are folded up in a tiny package, released with the early flowers, and unfolding over several weeks in spring, before starting to develop. This efficiency in packaging is unrivaled in even the most efficient engineered electronics packaging, and surpasses it in elegance.

Nature keeps it weird

Sassafras leaves

Sassafras leaves

Even after the young leaves unfold acrobatically, they remain their mysterious shapes and continue to astound us in their diversity. One of my favorites remains the versatile Sassafras (Sassafras albidum). A tree historically used to create flavors in root beer, as well as medicinal applications, the leaves have a variety of mitten and heart shapes. The picture on the right shows some of the red the leaves also hold onto throughout the season, and the more regular shape they hold.

Ginkgo Leaf

Ginkgo Leaf

One of the most recognizable leaf shapes is the non-native Ginkgo (Ginkgo biloba, on the left). This leaf shape often shows up in fashion patterns, jewelry designs, and more. While the tree is considered to be a living fossil (with no real wildlife value or typical ecological niche), it’s a great ornamental tree that is urban hardy, with fascinating leaf shapes, and an amazing fall color display. This tree is a conifer although it looks like a broadleaf tree. The conifer aspect is best displayed when it drops all of its leaves at the same time in the fall (common with deciduous conifers). Although it’s spindly branch shape, and elegant fan-shaped leaves remain throughout the year.

More on leaves.

This just highlights a handful of trees of the hundreds of trees native and planted in our area. Here are some great resources for exploring our tree diversity:

I’ve got my leaf, let’s go! – An online guide to find out what species of tree your leaf goes to

Leafsnap – A great local resource and free app for identifying leaves. The app does not always work, but the reference guide is impeccable.

Why leaves change color – learn about the colors hidden underneath the green.

Trees up close – A great book on appreciating the complexity of leaves and seeds

Toxic beauty: poison ivy (Toxicodedron radicans)

Toxic beauty: poison ivy (Toxicodedron radicans)

Benefits of Mulch and Composting in Arlington

Most Arlingtonians know that feeding your lawns and gardens with compost and mulch is good practice for maintaining a healthy yard and helping the environment. The benefits of using compost are plentiful:Free Mulch sign advertising the service at the Trades Center in Arlington, VA

  • Diverts organic materials from incineration, which is a last resort disposal method.
  • Adds organic matter and nutrients to soil.
  • Reduces the need for pesticides.
  • Reduces the need for fertilizers.
  • Increases biological activity in the soil.
  • Prevents soil erosion.

To promote these environmental benefits, the Solid Waste Bureau collects the County’s brush and leaves then processes them into leaf and wood mulch. Arlington residents can collect the mulch for free or it can be delivered for a fee.

Problems Arising Due to Persistent Herbicides & Pesticides

Some regions of the country have reported damage to vegetable and flower crops after applying compost and mulch that contained persistent pesticide or herbicide residues. Persistent herbicides can make their way into compost through leaf and yard debris. While most residual traces of herbicides typically breakdown in a compost pile in a matter of days, these particular compounds can be resistant for months or even years. Some alarms have also been raised regarding the potential for composting to affect groundwater quality. A common broadleaf weed herbicide named “2,4-D” has been detected in rural and urban streams and shallow groundwater at low concentrations.

Solid Waste Bureau Mulch Testing ResultsTrucks preparing for mulch delivery

To ensure the quality of County mulches, the County collected a series of samples this spring and had them tested. The first set were sent to Pacific Agricultural Laboratory where the Acid Herbicide testing protocol was applied. Of the 15 analytes evaluated, only trace amounts of weed herbicide “2,4-D” were detected. Additionally, mulch samples were sent to A&L Great Lakes Laboratories for testing under the Seal of Testing Assurance Program established by the U.S. Composting Council. Test results, which can be found online, indicate a high level of integrity and “vigor” suitable for plant growth and soil sustainability.

What Residents Can Do to Help

The Solid Waste Bureau will continue to monitor our mulch to ensure the quality is maintained. However, residents can do their part to help keep our mulch and compost free of harmful pesticides and herbicides by adhering to the following tips:

  • Keep pesticide/herbicide use to a minimum.
    In addition to potentially making their way into the County’s mulch and compost, repeated use of toxic chemicals may destroy the microbiotic life that exists to help maintain sustainable healthy soil.
  • Control lawn weeds naturally.
    Corn gluten, a nontoxic byproduct of corn processing, kills weed seedlings within days of application. It also adds nitrogen to the soil. It is 60% effective with the first application, but after several years, this method can provide as much as 90% weed control. Another organic weed control option is chelated iron, which can be used to treat broad- leaf weeds like dandelions, clover, thistle and more. The product overdoses weeds with iron but leaves the lawn unaffected.
  • ‘Spot-treat’ weeds to minimize herbicide use.
    Where only a few scattered broadleaf weeds such as dandelions are present, consider spot-treating individual weeds with household vinegar rather than applying herbicide over the entire lawn. Mix 5 parts white vinegar, 2 parts water, 1 part dish soap and apply with a hand pump sprayer.

Find out whether you need to mulch your yard or trees here:

Eastern Gartersnake

Eastern Gartersnake

Eastern Gartersnake

The Eastern Gartersnake (Thamnophis sirtalis) is a common, mid-sized snake, usually between 18 – 28 inches long, though the record length is 49 inches. It is normally found near water, but is extremely adaptable as to habitat, including being tolerant of people and disturbance. This makes encounters with them not uncommon.

Gartersnakes are some of our most cold tolerant snakes, often active when it’s too cold for other snakes to be out. They are among the last snakes to go find dens and overwinter in a dormant state. Their diet consists of various small creatures: amphibians, occasional rodents, invertebrates, but their favorites are earthworms and fish. They don’t like to climb trees, but are certainly capable of doing so if the need arises.

In late summer, they give live birth to 9-85 young, with the larger snakes producing the most offspring. If they’re lucky, they can live up to 14 years. When encountered, they may either try to hide at first or flee (their stripes causing them to be lost very quickly in the underbrush). If cornered or if they feel threatened, they will put on quite the show. They often flatten their heads and puff out, trying to appear as big and bad as they can. They are capable of biting, but their teeth are small, so the bite is not very painful at all. Occasionally some people have a slight reaction to the saliva, causing a mild itch, but this is very uncommon.

>> Read more at the Capital Naturalist blog.

Garden Alert

Garden Alert: Are these new invaders in your yard?

The list of invasive plants in Arlington County is always expanding. There are many reasons for adding a new species to Arlington’s invasive plant list, including new species sightings in our parks and natural areas, as well as demonstrated “invasive qualities” of a particular species in other jurisdictions in the mid-Atlantic region or locations with a similar climate.

Arlington’s list includes both “invasive” and “threat” plant species. “Invasive” plants are those that have been documented as non-native plants that spread into natural areas and cause negative impacts. All plants that have been categorized as “invasive” on our list have been found in Arlington County. Plants categorized as “threat” are species that are included in other invasive plant lists in our region but haven’t be documented in Arlington County, yet.  “Threat” species also include aggressive non-native plant species that have been found in Arlington County but are still being surveyed to access their negative impacts to natural areas.

Many new invaders and “threat” plant species are attractive ornamentals that are used in home landscapes. Due to their invasive tendencies, these plants should not be planted. If they are already present, it is wise to remove them before they can escape into natural areas. In the short-term, remove the fruiting parts of the plant to keep them from spreading. This isn’t possible for certain species of grasses or trees due to their large number of fruits.

The following plants have all been found in Arlington County Parks in the past few years and are transitioning from “threat” to “invasive” plant species. We are working to remove them from ornamental plantings around the County.  Do you have them in your garden? If so, check out the linked fact sheets from the National Park Service to find information about how to remove them.

Grasses and Herbaceous Plants

Fountain Grass
Pennisetum alopecuroides
Fountain Grass










Yellow Archangel
Lamiastrum galeobdolon
Yellow Archangel

Missouri Botanical Garden











Creeping Lilyturf
Liriope spicata
Creeping Lilyturf













Shrubs and Trees

Orange Eye Butterflybush
Buddleja davidii













Wintergreen Barberry
Berberis julianae












Pagoda Tree
Styphnolobium japonicum













The following internet links are considered reliable information resources on invasive plant species in our region and around the country:

Invasive Alien Plant Species of Virginia (DCR)

Center for Invasive Species Ecosystem Health Invasive Plant Atlas

Mid-Atlantic Exotic Pest Plant Council Plant List

Invasive Plant Atlas of New England

Southeast Exotic Pest Plant Council Invasive Plants of the Southeast


The American Bullfrog in Arlington


The American bullfrog (Lithobates, formerly Ranacatesbeianus) is the largest native frog in North America. It can grow to eight inches (203mm) and has traits that make it quite different from Arlington’s other frogs besides its size. It is quite variable in color, particularly when young and often confused with its smaller and much more common cousin, the green frog (Lithobates clamitans). The skin fold that begins behind its eye (the dorsolateral fold) goes around the eye rather than down the back as in the green frog. Learn more on the green frog here.


Unlike other North American frogs where the female, in order to be able to carry more eggs, is larger than the male, just the opposite is true of bullfrogs. The males are bigger, so when having territorial disputes, the larger males can force or bully the smaller ones away. The larger males have thus have greater mating success.

Males are quite easy to tell from females once they are adults. Not only are they bigger and have a yellowish throat during the breeding season, but their tympanum (eardrum) is larger than their eye. Females have eyes that are about the same size as their tympanums. These are all sexual differences their smaller green frog cousins also have.


Right now, males are now giving their “jug-o-rum” calls in Arlington’s permanent ponds. You can hear and see them do this in this video clip from the Capital Naturalist YouTube Channel.

Also unusual in frogs, the females will sometimes call, though this is normally the scream both sexes may give if they are caught by a predator. Some suspect that this release call attracts an even larger predator that might break up the attack and allow the frog to escape in the scuffle. I’ve actually heard the screaming several times and gone to investigate, interrupting a feeding snake in the process. In most species of frog or toads, only the males vocalize.


Once a female has chosen her suitor, she will lay a large floating mass of eggs – between 3,000-50,000. In less than three weeks, the tadpoles (also known as pollywogs) emerge. These tadpoles take two and sometimes three (up North) years to metamorphose into an adult. This again differs from most of our frogs, which grow into adult’s within a single season. The olive colored bullfrog tadpoles can also grow to be Arlington’s biggest tadpoles. Some polliwogs can be up to six inches long. Although they typically eat algae or detritus just like other polliwogs, they do rarely sometimes for meat and eat other tadpoles. Bullfrog tadpoles are distasteful to some fish, which allows them to live in permanent ponds alongside them.


Bullfrogs are notorious for eating anything smaller than themselves, including each other. I’ve seen them eat small mice, frogs and even snakes. Once, while watching a Red-winged Blackbird land next to the water during a children’s nature outing, a large bullfrog grabbed it and fought it for a while. Eventually, the ruffled bird got away. This voracious trait has resulted in some local extinctions of small animals.

Bullfrogs are the most commercially available frog tadpoles because they take so long to change into adults and can be kept with small fish in aquarium pet stores. For this reason, they are most frequently bought for release into home ponds. Because they will eat any smaller species, they have been outlawed for sale in some countries like England where they have been become an invasive predator of small ponds. They have even been implicated in the demise of California’s red-legged frog. Bullfrogs from Maryland were taken to California for their edible legs and for frog jumping contests, like that at the famous Calaveras Fair. Now they pose a threat to the smaller red-legged frogs which were already in trouble due to habitat destruction. It is important to realize that being native does not mean they belong everywhere, as that can upset the natural balance.


Bullfrogs, if they survive being eaten by each other, snakes, humans or the numerous other creatures who consume them, can live 15 years. It takes a male 1-2 years to reach sexual maturity (2-3 for a female). Their Latin name was given to them in honor of the great American naturalist Mark Catesby.

I truly appreciate these large frogs and their calls. Many times I’ve put aside my fishing rod or stopped what I was doing to try and sneak up on them and see what they are up to. I’ve been rewarded by many observations of them eating or being eaten. Luckily, these are tough amphibians that can survive in less than ideal conditions, including farm ponds and park lakes. But they do not belong in every body of water because of their great size and appetites. Now that you know a bit more about them, you hopefully can appreciate them more as well.