Don’t Tidy Those Messy Streams

By Kevin McKeon, Maine Master Naturalist

Maine’s 32,000 miles of streams are one of its most important natural resources. Various protective laws exist with restrictive requirements that are often met with head-scratching as to why. Here are some reasons.

To Native Americans, streams were trade and travel routes as well as valuable food sources to be revered, cherished and protected. But the past few centuries have brought non-native human incursions, with different lifestyles and perceptions, regarding our environment. Waterways became a tool to be modified. Streams got dammed for the building of water-powered grain, lumber, and fabric mills. Large hydro-electric dams sprouted to power industrial growth. Dam impoundments formed ponds and lakes which became exclusive homesites. These events caused the characteristics and landscapes of streams to drastically change, along with the critters that lived in and around them. Disruption of traditional livelihoods ensued.

Civility required the formation of water use and rights laws, leading to water quality protection laws. They will most probably remain in flux for the foreseeable future as we discover factors that both impede and enhance streams’ water quality, quantity and the critters living in and around them. One of the things we’ve learned is that a “messy” stream is a healthy stream.

Streams naturally form by the landscape’s need for water drainage. Rainfall and gravity combine with the erosive effects of water flow to create the streams’ banks and beds, becoming contained in downhill flows along often sinuous paths. These waterways are sometimes altered due to turbulent flow events caused by torrential rains and sudden heavy snow melts but eventually become rather permanent.

Sometimes, folks feel the need to “improve” a nearby stream by straightening or redirecting it, removing protective riparian vegetation to improve views. They may “clean” the stream of logs and branches or line stream banks with stone to “fix” erosion. These actions often cause less water of lower quality to be absorbed into the landscape due to resultant less-restricted flows. Both flood and erosion risks are increased, creating damage to roads and property.

The straightened stream is shorter than the previously meandering one, reducing riparian areas. Thus, aquatic wildlife quality, quantity and diversity are also reduced. Removal of wood litter and stones destroys and decreases the formation of many types of habitat and wildlife. Insects and amphibians that live and shelter in the wood are impacted due to reduced eddies that trap food sources. Lowered water turbulence reduces oxygenation, suffocating fish, plants and amphibians. Pools that form for various wildlife degrade. Basking sites for turtles, snakes and birds are lost. Hunting and traveling platforms for heron, mink and fox get eliminated.

All this to say that stream “messiness” is a good thing. By keeping logs and branches — “large woody debris” — where they lay, a stream’s natural, meandering path through the landscape is maintained. Downstream flooding is mitigated, and habitat and species diversity is conserved. Logs and branches collect fallen leaves and other debris and ephemeral pools and sand bars form to create habitat for aquatic insects-the basis for the food chain. The complex underwater habitats of large woody debris, piled sand, river stones, and vegetative dams offer diverse shelters for a multitude of aquatic wildlife supporting vibrant riparian landscapes.

“Messy” dams also serve as filters, catching gravel, sand and silt from the water column where it accumulates and forms rich, underwater meadows where aquatic plants thrive and provide yet more habitat for the riparian areas. Anthropogenic pollution settles here and the rich meadowland allows the formation of aquatic macro-invertebrates that actually eat that pollution! Submerged wood is also important as a direct food source: More than 20 different species of aquatic invertebrates in our region rely directly on wood for food. These so called “miners” tunnel into underwater logs and branches, consuming wood as they go. They include the larvae of beetles, mayflies, caddisflies, stoneflies and true flies. Collectively, they play a critical role in the aquatic food web.

Stream health studies will almost always include documenting the presence of large woody debris, as this is known to be a key health indicator. Stream restoration work at Sanford ’s own Goodall Brook — the Goodall Brook Watershed Management Plan — advises the addition of woody debris. But don’t just do this without proper guidance and authority. The permitting process, although head-scratching, protects our valuable waters. Hopefully, there’s now a bit more understanding for this need. Do feel free to remove plastics, tires, shopping carts, and such. And inform folks that altering their boundary stream to “look better” is most probably not a good idea for the backyard wildlife…or their wallets if they get caught! It’s best to let sleeping logs lie!