This article is one in a series that draws connections between wetlands and the human community.
The dragonfly – a common symbol of summer, day camp, and days spent at the lake. Known for its swift zip through the backyard, and acclaimed for being a mosquito-eater. Beyond these familiar traits though, these macroinvertebrates are full of insights, from connections to their environment to folklore.
In both adult and nymph phases, dragonflies are a top predator of the insect world. Their family name of Odonata comes from the Greek word odonato, meaning “tooth.” Cousin to the dragonfly is another familiar flyer, the damselfly. To help tell them apart, dragonflies are generally larger with bulkier bodies than damselflies. Both dragonflies and damselflies have two sets of wings, but damselfly wings are the same size for both the front and rear sets. When at rest, dragonflies hold their wings out like an airplane, but damselflies fold their wings closed over their back.
Before emerging as a high-flying adult, dragonflies can spend up to several years in their egg and nymph phases. Scurrying about on aquatic vegetation and submerged wood, they feed and grow by either chase or ambush, and sometimes both. Swift in the water, dragonfly nymphs use jet propulsion like an underwater Jet Ski. This makes for a deadly strike, and helps dodge larger predators like bass and pan fish. To secure their catch, dragonflies clench down with spiny teeth known as thorns. Like a tiny T-rex, an impressive jaw called a protruding mandible stretches out to about the ratio of an outstretched human arm. With such ferocious features, dragonflies can feed on prey larger than themselves, from small fish to tadpoles or even newts… chomp!
In addition to transportation, jet propulsion is also a dragonfly’s lungs. Like humans sensitive to air quality, the continual in-and-out of breathing makes a dragonfly nymph highly dependent on its aquatic environment. Scientists use dragonflies and other sensitive species as an indicator of water quality. If dragonflies, caddisflies, or stoneflies are present in a lake or stream, it shows a trend of good water quality. Conversely, aquatic worms, sow bugs, and scuds are more tolerant to contaminants and pollution, thus showing a trend of poor water quality. To sustain dragonflies, habitat with sticks, rocks, and any texture they can find, helps them hunt and hide. One threat to this habitat is sedimentation, which can smother the nooks and crannies, forcing dragonflies to search for space elsewhere.
Sedimentation is a common pollutant in the Vadnais Lake Area Watershed, hitching a ride into lakes and wetlands with stormwater runoff. Although it’s natural, our style of development has created a double-whammy in how sediment impacts infrastructure and water quality. The first is that the built landscape of streets, short turf grass, and bare slopes speed up the natural process of sedimentation, sending it into our lakes and wetlands faster than nature does on its own. The second is that a system of meandering creeks and wetlands has been transformed into a system of straight channels and ditches. While this is efficient for getting water away, channels and ditches prevent sediment from depositing along floodplains, and increase velocity to do more damage on banks. This leads to more sedimentation, which creates maintenance needs, and continues to smother aquatic life. To top it all off, sediment becomes a trap for whatever else is on the street - free floating nutrients, salt, auto fluids, or cigarette butts. All of which make their way into water as the sediment moves with runoff.
In Chinese feng shui, the lore of the dragon is attributed to the aerial curvature of streams across a landscape. Dragons, as a symbol of power, strength, and luck, are said to control rain and floods, balancing the universal energies of yin and yang. While esoteric, the connection between dragons and streams has a surprising tangible link. In feng shui tradition, everything connects to the flow of energy. Colors, patterns, buildings, even the design of a neighborhood. According to feng shui principles, favorable or positive energy is assigned to natural, flowing curvature. Straight lines are unbalanced and dominated by yang energy. In abundance, all this yang energy creates “hidden arrows” that foster subtle notes of negativity. In ancient China, these concepts are said to have served as a guide for engineers, home builders, and families alike. This thoughtful planning for where to build, where not to build, and how to foster positive energy in the planning process helped minimize risk and preserve nature’s balance. Done well, this sort of holistic planning supports a long-term vision of sustainability, or at the very least fewer headaches, for everyone involved.
Reflecting on our own engineering habits, we can see that our history of A-B design has consequences later on. Straight ditches create more velocity, and gradually fill with sediment, and this calls for periodic (and costly) maintenance on banks and culverts just to keep up. A straight ditch through a wetland also sends more flood water downstream than it stores, which likely becomes someone else's problem. With a meandering creek however, the spaces between the curves become a floodplain. These curves, with more space and a slower pace, support water storage and sediment deposits during high water levels. In a drainage system with floodplains, both water and sediment have somewhere to go beyond the main channel. Floodplain vegetation adds a buffer for the stream, which creates a filter to absorb excess nutrients, and keeps water and sediments moving slowly. Slow water can be a good thing, if there’s somewhere for it to go.
VLAWMO is embarking on an exciting project in 2020 to meander a portion of Lambert Creek – at the former site of Lambert Lake (near County Road F and Centerville Road). Grant funds have been awarded by the State, and planning is underway in partnership with the U of M Department of Bio-systems. As several other metro watersheds have demonstrated, a stream meander is a step towards increasing flood storage capacity, dealing with sedimentation more effectively, mitigating downstream flooding, and creating healthier habitat for critters such as dragonflies. Rather than a quick-fix of costly dredging, it writes a different story.
In the past 100 years, our modern focus on efficiency, control, and quick building have had consequences that we now grapple with. Our local Lambert Creek is just one of many examples that echo the issues facing the mighty Mississippi. For example, Lake Pepin in Southern Minnesota is threatening to fill with sediment, while river communities down to the gulf are stuck in a cycle of levee building. Lacking upstream storage, one must build bigger walls and pass water on to their downstream neighbor. In many cases one or a few neighbors, or in the case of the Mississippi a few communities, bears the brunt of the larger trend of getting water "away." The "hidden arrow" of feng shui may well be the cycle of finger pointing, traveling upstream from neighbor to neighbor.
But perhaps there’s wisdom in the ancient lore of the dragon… that to create balance and thrive is to surrender some control back to nature’s ancient systems. Back to the ebbs and flows, to the curves of the dragon in the landscape. Scholars and psychologists such as the late Carl Jung theorized that myth is a vessel for hidden truths; that myth returns to a collective in a time of need. A hard truth we're now facing is that we haven't made space for floodplains. Not restoring them could be more costly than the hard work it will take to restore them. While the northeast metro isn’t a hub for Eastern mythology, there does seem to be an air of negativity and gridlock surrounding drainage ditches. There are no flying mythical beasts to be found, but tiny dragons dwell in our midst with protruding mandibles. Perhaps our dragons have something to teach us about water management. Perhaps a clue for how to both survive and thrive, is scurrying in the sediment.
Keep up with VLAWMO’s Lambert Lake meander project or check out tips for reducing sediment in stormwater runoff. Learn about our LeafPack program, a volunteer opportunity to monitor macroinvertebrates in the watershed.
-Nick Voss, VLAWMO Education & Outreach Coordinator