Going natural: Fixing a man-made mess one stream at a time
In recent years, "going natural" has been the "in" thing with everything from what we eat and drink, to how we look and dress, to where and how we live. Going natural is also now the "in" thing when working with natural resources.
In the past, when dealing with problems in nature, many solutions involved trying to force nature to do what it should do, according to what man and science determined. In too many cases, the forced resolutions created additional and sometimes even larger problems. Such is the case of the red clay dams in the Nemadji River Watershed.
We hear so much about this red clay. Just what exactly is it and where did it come from? How have we handled it before and what may work in the future?
We have to go back in time to really understand.
During the Ice Age tens of thousands of years ago, glaciers covered much of northern Minnesota. These extensive sheets of ice sculpted the hills and valleys and the rivers and lakes, including Glacial Lake Duluth, the predecessor to Lake Superior.
The Superior Lobe of the glaciers picked up rocks that carved and scoured through ancient volcanic and granitic bedrock to create the vast expanse and depth of Lake Superior as well as its dramatic and beautiful shoreline and cliffs. They also cut and moved some of these rocks many miles away. Other rocks were shoved and tilted in different configurations, and many more were ground into tiny grains of sand, called "mineral flour." The rhyolite volcanic rocks comprising much of the North Shore red cliffs, like those at Palisade Head and Shovel Point, themselves produced tons of "mineral flour."
As the weather warmed, the glaciers started to melt, but the resultant water couldn't flow away due to an "ice plug" at Sault Ste. Marie. The meltwater filled Glacial Lake Duluth to 1,100 feet above sea level and flooded the surrounding land, including the Nemadji River Watershed where it carried tons of rhyolite "mineral flour." When the ice plug melted, the waters drained down to 600 feet, but many tons of this reddish "mineral flour" — what we now call red clay — was left behind.
Through the thousands of years following, flowing waters carved streams with wandering paths throughout the watershed and to the Nemadji River. These waters naturally picked up the highly-erodible red clay silt and eventually carried it to Lake Superior. This was nature acting naturally.
MAN-HANDLING RED CLAY
In the 1800s, immigrants settled in northeastern Minnesota and northwestern Wisconsin, a land of vast natural resources. Shipping out of the Duluth and Superior harbors became vitally important to carry the products of the many mining and logging industries. Through the years, the ships became bigger to carry more products, and soon the shipping channels needed to be dredged for the heavily laden ships to get through without dragging bottom. The tons of red clay flowing into Lake Superior from the Nemadji River Watershed added significantly to the dredging load.
These logging products, however, were the cause of increased red clay carried to the bay and lake. Because so much land was clear cut, there were few trees to slow down run-off waters. Streams full of fast-moving water cut more deeply into the land, thus causing more erosion and movement of red clay soil down the streams and river and eventually to Lake Superior. Even though the Nemadji Watershed is again forested, many of the erosion problems we see in the watershed today are due to the effects of that time.
In the 1970s, the U.S. Army Corps of Engineers (responsible for the dredging), along with natural resource professionals from several agencies, decided that it was time to reduce some of the red clay flowing into the lake. Hence, the creation of the red clay dams to force stream waters to stop behind the earthen dams, drop their red clay silt into the created pond, and then divert through the dam via a metal outlet pipe to continue its way to its destination.
These red clay dams seemed to work … at least for awhile. The red clay load carried to the lake was somewhat reduced and landowners enjoyed their beautiful ponds. However, as the years went by, the stream waters continued to slowly and steadily eat away at the earthen dams, seeking ways out to continue their natural flow. The metal pipes also rusted, and then leaked, and soon the water started to flow around the pipes in addition to through them.
Eventually the stream waters chipped away enough of each dam, and the dams started to "blow out" one by one and the waters burst through. The ponds drained and carried huge loads of the tons of red clay sediment that had built up in the ponds.
A logical mind would think that after the big "blow outs," the streams would eventually go back to natural and all would be well again. However, the stream banks of red clay were very unstable and kept sloughing, thus dumping even more red clay into the river. The sloughing also prevented plants and trees from taking root to help provide stability. In addition, the streams started downcutting (making deeper channels like miniature "Grand Canyons”) and headcutting (creating mini waterfalls that continue to migrate or eat backwards upstream and erode more of the stream bed and banks).
As a result, the streams are again carrying huge amounts of red clay silt to the river and the lake.
This increased load of red clay is very detrimental in many ways. It reduces water quality for drinking, swimming and recreational activities. It restricts light penetration needed for aquatic plant life. It increases sediment deposits on the stream and river bottom, covering spawning beds and habitats, and thus reducing the numbers of fish and aquatic animals. This increased red clay silt is not good and not natural.
It takes decades for any stream to stabilize and find its natural way from its starting point to its destination, and the stream's natural flow is always changing to accommodate difficulties it encounters along its way. But some streams, like these in the Nemadji Watershed with their unstable red clay, may need a little help to get back to being natural, stable and healthy stream systems.
To help these streams, professionals are now turning to Stream Restoration Design or Natural Stream Design (NSD)…a "new old" way to help streams "go natural." NSD is based on science and engineering and history, plus years of experience with good and bad restoration projects. NSD works with streams, not against them by forcing them to do what they wouldn't do naturally.
The Carlton County Soil and Water Conservation District (SWCD) is using NSD to help Nemadji Watershed streams "go natural" by removing the blown-out red clay dams and returning the streams to natural channels with natural designs. But what is involved in this new NSD way of work?
Like many sciences and projects, NSD involves investigative study, designs and plans, and implementation.
The first step involves studying the stream/river from every aspect.
According to Melanie Bomier, Carlton SWCD's water resource technician, the investigative study looks at water quality: clarity, contaminants, etc. It looks at history: how the stream's channel and flow have changed and what has been done to the stream by man and nature over many years. It looks at the biology of the stream and watershed: the fish and animal life as well as aquatic and surrounding landscape plant life, etc. It looks at the geomorphology of the watershed: the landscape, topography, and geology, as well as what created, affected and may eventually change this watershed, whether natural or man-made. This study involves a lot of time and research.
Step two involves analyzing the investigative data and designing a natural stream engineering design. Comparable to a blueprint for a building project, those who do the work will use this engineering design to guide their work on the restoration project.
While step three, the implementation, involves the most material and physical labor, it usually takes less time to accomplish than either of the first two steps. Implementation tries to use natural materials as much as possible in different ways to help nature "go natural."
Here are a few NSD methods the Carlton SWCD used on a recent red clay dam removal project on an unnamed stream that flows into Deer Creek (which flows into the Nemadji River). This project was funded by the Great Lakes Restoration Initiative and the Clean Water Land and Legacy Amendment.
Meandering is a natural way for streams to wander through the watershed. In this project, where the stream's route was recreated through the removed red clay dams, meanders were created for the stream. Meanders are needed to slow down the water flow. In comparison, it would be like taking a straight road, where you can speed from one end to the other in 30 seconds, and putting in curves that would slow you down and take two minutes to go the same length. Meanders help greatly with reducing the energy in the water thus reducing erosion and dissipating the impact of flood waters.
In areas where the banks rise too high too quickly, a flood plain was created. In flooding situations, if the water can get over the bank and spread out, this will slow down and take some of the destructive energy out of the rushing water. If the banks are too high and the water can't get over the crest, increased water flow and pressure will erode the bottom of the river and start cutting it down further, thus creating the miniature Grand Canyons. These may look pretty, but they are bad as they cause increased sedimentation, erosion and bank stabilization problems as well as increased water pressure and speed. Creating a floodplain can be as simple as bulldozing the landscape into a gentle upward slope away from the river.
In places where the stream bank needs to be stabilized or strengthened, the use of big rocks set against, or logs jammed into, the banks will help to keep the water from eroding the banks any further. This also helps stabilize the soil thus giving grasses, plants and trees time to grow and spread their roots, thus giving even more stability as their roots grab onto and hold the dirt in place. These trees and plants will also filter sediment and contaminants from runoff waters, provide food and shelter for aquatic animals and fish, and shade to reduce the water temperature.
Another way to slow down the water is by using rocks to create "stream vanes" and "step pools."
Kelly Smith, conservation technician with Carlton SWCD, explained that the stream vanes are meant to direct water away from the banks, “to tumble the motion so the water flow loses energy, to direct the flow towards the middle of the channel, and to form a step pool, which also slows down and takes energy out of the stream."
The stream would then have a series of small waterfalls with a little pools at the base of each waterfall. The impact would be comparable to driving over a bumpy road. You (and the water) will be forced to slow down and "rest" after each bump.
To help stabilize the banks along the river, plus create better habitat, most stream restoration projects also include laying down erosion control mats, or blankets, and planting grasses, plants, and trees.
"Live stakes" can also be used. The stakes are 3 foot (or longer) sticks, about 1 inch diameter, cut from live, but dormant, willow trees. Pounded into the ground — with a couple of bud knobs left above ground — in the floodplain area of the stream, these live stakes will eventually develop roots and grow into willow trees that will further stabilize the soil and cool the water.
There are many other ways that stream restoration design can help streams "go natural" but at a faster pace than nature could naturally do the work. Bomier explained that NSD improves water quality, doesn’t require maintenance like dams or other structures, and are better able to handle floods.
“They also improve habitat and promote more biodiversity,” Bomier said. “If we can make the stream stable using Natural Stream Design, then we fix the problem rather than just put a Band-Aid on it."
Kim Samuelson is Carlton SWCD's elected supervisor for District 4. For more information about the Carlton County SWCD, the red clay dams or stream restoration design, call the office at 218-384-3891, check them out on Facebook, or go to their website at www.carltonswcd.org.