One of the most common questions we get in the water conservation world comes from landowners who have streambank erosion on their property. We wish the answers were simple…. but they aren’t. This page will provide some background on what causes streambank erosion, and various types of solutions depending upon the circumstances of your particular situation.
Stream Bank Erosion Summary
- There are many possible causes of bank erosion.
- Streams should ideally have gently sloping, fully vegetated banks.
- The best way to avoid property damage is to discourage building structures in the flood plain, which gives the stream enough room to flood during times of high flow.
- Most work on stream banks requires extensive state and federal permitting – don’t put a shovel or any heavy equipment anywhere near your stream without consulting professionals and the Pennsylvania Department of Environmental Protection.
- There is a lot that homeowners can do to improve fish, bird, and other wildife habitat.
What causes stream bank erosion?
Why is the stream in your backyard eroding? Often, it is impossible to know for certain. But below are some of the most likely causes:
- Changing weather patterns are causing more intense rain events. When a stream channel has to handle much more flow on a regular basis due to larger storm events, the banks will erode to make more space for that water.
- Development also is a factor. If the watershed area above the erosion had been in forest, or meadow, and it is now roofs and pavement, more water will run off during large storms. This greater volume of ‘stormwater’ will cause stream banks to erode to make more room in the channel for flow. Stormwater regulations require developers to manage increases in stormwater from from their development. These stormwater management facilities are typically designed to address runoff from smaller storms. Few stormwater basins or other stormwater features are designed to handle very large flooding storms.
- Your stream may have what is called ‘legacy sediment.’ All the smaller streams in the region were once dammed up for mill dams – that is what provided power before electricity replaced water power for running grain and saw mills. The mill dams would fill in with dirt (sediment) over time. Sometimes that would be many feet of sediment!! Then, as the dams breached, the streams would start cutting down through that old pond site createing steep-sided and easily eroded stream banks. Vertical, fine-grained banks are often an indication of legacy sediment issues.
- There are also many one-off, less common causes of erosion. Major upstream modification of the stream, such as a bridge replacement or channel relocation, could have significant impact on the way water flows to your property. Or changes may have been made to storm pipes, changing how and where water flows past your property.
It may not be necessary to understand what the cause is of the erosion to address the problem.
How Streams Are Supposed to Function
Regardless of the size of the stream in your backyard – from a trickle to the Delaware River, streams and rivers flood. How often, and how high varies a great deal, but all streams and rivers flood. The area around the stream that is prone to flooding is called the flood plain. Some flood plains are mapped by the government, and some are not, but every flowing body of water has a flood plain.
Flood plains should be fully vegetated with full-height grasses, trees and shrubs. Lawn grass is inadequate vegetation for a flood plain. Lawn grass roots are only as deep as the grass is high, and the shallow root system does not provide protection against stream bank erosion. Meadow grasses can have roots several feet deep and trees and shrubs as well; these deep roots will absorb water and hold the soil in place. This is the type of vegetation that can protect your banks. Ideally, streams should have full-height buffers as wide as possible. That allows flood waters to rise slowly and flow more gently across the edge of the stream.
An added bonus of planting trees, shrubs, and native flowers and grasses along your stream is the benefits to wildlife. Streamside trees and meadow are incredibly important for birds, amphibians, and mammals that move along the stream corridor during the day and at night. And the shading that trees provide to streams cools water temperatures, improving habitat for cold-water fish like trout. Further, the leaves that fall into streams in the fall (leaf pack) along with any twigs and branches (woody debris) are very valuable for many types of fish and aquatic insects (which are what the fish eat). Some species of aquatic insects will only lay their eggs on the underside of a log overhanging a stream!
But My Bank is Collapsing and I’m Losing Feet of My Property! My Shed is About to Fall into the Creek! My House is Going to Be Undermined! What Can I Do??!!
The answer to that is….it depends. Below are some facts on what landowners can do about streambank erosion.
- First, and most importantly to know, any earthmoving – whether with heavy equipment or just a shovel – in or near a stream bank is going to require state, and possibly federal permits. The penalties for violating this condition can be significant. Do not do any earthmoving without consulting a professional. For any questions relatting to required permitting, call the Pennsylvania Department of Environmental Protection. In the Lehigh Valley region, that number is 570-826-2511.
- If your home or other expensive structures are being threatened, you may qualify for an emergency permit, but even in that set of circumstances, a landowner must comply with permitting conditions.
- There are many things you can do that will help, without a permit – and all of them involve plants!
- Create a no-mow zone as far back from the stream edge as you can. As the grasses and flowers grow taller, their roots will grow deeper and they will provide more protection for your stream bank.
- If you don’t like the idea of just letting the grass grow, there are many options for growing beautiful, native grasses, flowers, trees and shrubs. See our linked publications – but there are many places to get ideas, and you can always call a local native plant nursery to help you design a beautiful streamside landscape.
- Live-staking – planting branches of one of a number of native shrubs that will take root directly from a cutting – is one of the best ways to help stabilize eroding banks – and no permits are needed! To learn more about live-staking, check out this 12-minute video and this fact sheet. Here is a list of species suitable for live-staking. Contact us for more information on where to get live-stakes – we have several live-stake nurseries in the Lehigh Valley!
Plants Aren’t Going to Do the Trick in my Situation – I am Going to Need Rock and Concrete!
Surprisingly, ‘hard’ bank solutions – rock, gabion baskets, and concrete, can make your erosion problems worse over time. They provide ‘nick points’ – wherever the rock or concrete meets soil – for fast-moving water to scour. Rock and concrete along the banks can move the problem upstream – or downstream, and cause major bank collapse in new places. And, ‘armoring’ the banks requires engineering, and permitting. In some cases, armoring is the correct solution. But, this approach is a major expense – in the tens of thousands of dollar range. You will need professionals to help with permitting, and most likely you will need to hire heavy equipment operations and purchase concrete or stone. And skip the ‘creative solutions’ altogether – old tires, chunks of asphalt, railroad ties and the like. They will only wash downstream, polluting the water, and will not work to stabilize your banks.
If you need recommendations for professionals who can help you, one suggestion would be to call your municipal zoning officer – that person may be able to point you in the right direction. Your local County Conservation District is another local resource for help with requirements for streambank construction projects.
Stream Restoration for Fish Habitat
If you are interested in working on the stream on your property to improve cold-water fish habitat, there are many resources available. Even if you do a project soley to benefit fish, you will still need permitting if any earthmoving is involved – and there often is – where large rocks are placed to create pools, or logs are used to create deeper scouring in the middle of the stream, causing the water to flow more quickly. There are many resources available for fish habitat improvement projects, and several local Lehigh Valley conservation organizations have completed dozens of stream improvements over the past years.
But Stream Work is So Expensive!! I Need Grant Funds to Pay for it!!
Unfortunately, grant funds are not normally available to help private landowners to pay for in-stream work requiring permits and heavy equipment. If the stream is on private land, the private landowner is usually responsible. But, if you contact your local watershed association, it is possible that they can help if the solution you decide is right has to do with planting and live-staking. For a complete listing of watershed associations in the Lehigh Valley, see the tab in our dropdown menu or, send us an email at watershedcoalitionlv.org.
Have More Questions? Contact us at the email address above, and we can try to help.
Page contents developed by the Watershed Coalition of the Lehigh Valley, the Wildlands Conservancy, the Northampton and Lehigh County Conservation Districts, the Bushkill Stream Conservancy, the Monocacy Creek Watershed Association, the Martins-Jacoby Watershed Association, the PADEP, and the PA DCNR.