Process Based Restoration
Process-based restoration (PBR) is partnering with nature to restore health and longevity to degraded river and stream ecosystems. Instead of using heavy machinery to alter streams to suit our immediate needs, we use mostly hand tools, human labor and all natural materials to give streams what they need to be in their healthiest state.
Why BDAs?
Did you know that beavers alter their environment more than any other animal on Earth besides humans? That’s how they earned their nickname “Nature’s Engineers”. Beavers build dams in creeks and rivers in order to create deep ponds with consistent year-round water where they can dive to safety from predators. Their dams slow the water down, spreading it out over the landscape, and allowing it to sink into the groundwater table (think slow it, spread it, sink it). By building a series of dams, the beavers transform single thread rivers and streams into lush wetlands, and that is what brings these wide ranging ecosystem benefits:
-
Fire resiliency
-
Groundwater recharge
-
Increased biodiversity
-
Carbon sequestration
-
Erosion control
-
Improve water quality
-
Lessen flood intensity
Addressing the Source Problems
Incised channels hold little water and little life. These simplified channels act more like high-speed water conveyance systems than quality habitat. Because all of the stream energy is localized with nothing to slow it down, the stream power eats away at sediment on the channel bottom - amplifying erosion and incision. Soon most of the water has rushed out of the system into the ocean, leaving a stream with little or no water for much of the year. Our main problems:
-
Water is flowing too fast
-
Sediment is escaping the system
-
Water is confined to one channel
-
Left without the tools to naturally recover
Nature Shows Us
The Solution!
Principles of BDAs:
-
Streams need space.
-
Structure forces complexity and builds resilience.
-
The importance of structure varies.
-
Inefficient conveyance of water is often healthy!
-
It's okay to be messy.
-
There is strength in numbers!
-
Use natural building materials.
-
Let the system do the work!
-
Defer decision making to the system.
-
Self-sustaining systems are the solution.
Beaver Dam Analogs and Post Assisted Log Structures
BDAs and PALS are by nature messy! They resemble either beaver dams or natural wood-loading, and thus they are a densely packed mound of wood, sediment and vegetation. Depending on the available materials and location in the stream, the size and form of the structures will vary. What is important is their intended function. Structures are strategically placed and designed with certain processes in mind to nudge the system back to self-sustainability. Structures usually take on one of two forms: channel spanning or bank attached.
Channel Spanning
Channel spanning structures create ponding and catch sediment on their upstream side. These ponds provide important habitat during the summer when flow is at its lowest and serve as speed bumps during high flow events, slowing the water and giving the sediment a chance to settle and collect. Ideally structures can raise the water level enough to reconnect to the floodplain allowing floods to dissipate over their floodplain and providing nutrient rich soil to the area.
Bank Attached
Bank-attached structures are ideal for incised, high flow areas. They don’t try to hold back water. Instead, their goal is to redirect water around the structure, encouraging sinuosity and sediment redistribution from the high bank opposite the structure and deposition both in front of the structure and in the eddy behind it. They are crucial for directing sediment back into the channel where it can accrue behind the channel-spanning structures downstream for floodplain connectivity.
A Different Kind of Restoration
What makes BDAs different from most restoration practices is that it is an ongoing relationship with the creek. The structures are semi-permanent in nature, and we plan on building more and adding to them over time. Instead of over designing and constructing a single feature that meets our immediate needs, but degrades the ecosystem, we are working with the system, adding the natural inputs that the creek needs. This is how to evolve a degraded creek, back to a healthy, self-sustaining ecosystem.
Coexisting with Beavers
They’ll survive, and your property will thrive!
Why is a beaver on my property?
and what can I do about it?
Beavers have been native to California for millions of years, but they were almost completely removed as a result of the fur trade. Humans moved into the bountiful areas beavers used to call home, and now a recovering beaver population finds itself in conflict over land. Landowners are in the predicament of incurring possible property damage from flooding or unwanted tree chewing if a beaver moves onto their property. Oftentimes beavers will be killed if conflicts arise, but that practice is more expensive in the long-run because other beavers are likely to move in. Luckily, there are easy, cost-effective solutions that allow us to live with beavers and enjoy the benefits they bring to the area. We at Nature’s Engineers are trained in managing beaver conflicts and are here to help you turn any beaver problem into a long lasting solution. Oftentimes, beavers will be lethally trapped to prevent them from felling trees or causing flooding on private property. However, there are low maintenance, cost-effective solutions that will protect your trees and prevent flooding.
Why live alongside beavers?
-
Tree protection
-
Flood prevention
-
Culvert protection
Beavers are water bringers. With the challenges we face from drought, wildfires and water shortages, there has never been a more important time to protect and sustain the water on our land, and beavers do just that by naturally restoring our rivers and streams. By building dams and digging channels, they provide themselves with safe habitat and turn degraded streams into lush wetlands. These healthy wetlands bring huge benefits such as recharging the groundwater, lessening the intensity of floods, creating fire breaks, and providing a crucial habitat for our wildlife. They are an oasis of life, and if you’ve never been to a beaver pond in person, we’d love to lead you on a tour. You can sign up for a Watery Walk to a beaver dam with Audrey and Cooper by clicking this link.
Why do beavers chew trees? Chewing trees is the most common human-beaver conflict. Beavers chew trees for two reasons: food and building materials. They can’t digest the hard inner wood, so beavers strip off and eat the leaves and softer outer bark. This leaves them with good, cleaned wood sticks and logs that are perfect for building dams and lodges. This way the beavers can create ponds of deep water that not only keep them safe but are lush wetland habitats that encourage more trees to grow.
Tree Protection- is the process of enclosing the tree with wire fencing from ground level to breast height. Leaving enough room for the tree to grow ensures the tree stays healthy and the beavers can’t get in. This process should be redone every 2-3 years to accommodate tree growth. If you want to encourage the beavers to stay in the area, it is best to select only a few trees to protect, so that the beavers have enough food to remain. If you want to passively remove the beavers from your property, wrapping enough trees usually forces the beavers to move on to a new area.
Flood Protection- If a beaver family builds a dam in your creek, it could mean unwanted flooding for your property. Luckily, we have the technology to control the water level of beaver ponds, so that flooding is prevented, and the lush beaver wetland and all of its benefits can remain. Pond Leveler devices A.K.A Flow Control devices (see above) are a trusted and reliable tool that have solved beaver flooding conflicts for over 20 years. Over a thousand devices have been successfully installed all over the U.S and Canada and continue to work to this day.
How do the flow devices work? A pipe is run through the beaver dam at a certain height, and essentially acts as a leak through the dam. The water then flows through the pipe so the height of the pond can never rise above the pipe level. An exclusion fence is attached at the pipe inlet to prevent beavers from getting close. This boundary creates enough space that the beavers cannot feel the flow of water leaving their pond. And, as long as the water depth is at least 3 feet, the beavers will likely stay. A successful flow device installation would result in a stable, flood-proof beaver pond that continuously brings benefits to you and the land and water around you.
Culvert Protection- Human made infrastructure like culverts and other drainage structures create natural choke points in rivers and streams that are ideal for a beaver to build a dam and create a pond. Thankfully, nearly all man-made structures can be prevented from beaver damming. There are several strategies that can be taken to either prevent damming or control flow through a dam depending on the situation. With a little thoughtful engineering any area can be made co-habitable for beaver and human use. These strategies consist of placing protective fencing or a diversion dam around an existing culvert or drainage structure. All of these techniques are effective, and the different strategies are employed depending on the site conditions.
Aerial imgery of beaver habitat on the Salinas River, Atascadero, CA. Courtesy of Dr. Emily Fairfax and the SLO Beaver Brigade
Captions
Beaver habitat on the Salinas River in Atascadero, CA. Photo by Brittany App
Beaver coexistence devices © The Beaver Institute