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7 ways to repair an eroding lake bank, compared

There are 7 common ways to repair an eroding lake bank: regrade and sod, geotextile wrap, geotubes, riprap, sheet pile or a seawall, a littoral shelf, and a rebuilt slope with rooted grass. Each one solves a different problem, and the right choice depends on how steep the bank is, how close it is to homes and structures, and what residents expect the lake to look like when the work is done. For most community lakes, where a grass slope has lost its soil, a repair that rebuilds the slope and gets the grass to root into it is the best fit.

Why boards hear different answers from different contractors

Boards are usually offered 1 or 2 of these options, depending on which contractor walks the lake. A contractor who installs rock tends to propose rock. A contractor who mows tends to propose regrade and sod. That does not make either answer wrong, but it means the board is often comparing a single option against doing nothing, rather than comparing the options against each other.

The 7 lake bank repair options side by side

A closer look at each option

Regrade and sod

A crew pushes soil back onto the slope, shapes it, and lays sod on top. It looks finished the day the crew leaves. The trouble is that nothing holds the bottom of the bank, where the water does its damage, and new sod on loose fill rarely gets the calm weeks it needs to root before the next heavy rain. We cover this in detail in why regrade and sod fails.

Geotextile wrap

Fabric is laid at the base of the slope, filled with compacted soil, and folded back over itself to form a firm edge, then sodded. It holds better than loose fill. It works best on gentle slopes. On steeper banks, or where the sod does not take, the fabric can end up exposed at the waterline, which residents notice.

Geotubes

Geotubes are fabric tubes filled with sand taken from the lake. Once the sand settles and the water drains out, the tubes are opened and the sand is spread to rebuild the slope. This can make sense on large projects where there is plenty of sand in the lake. The drawback is time and appearance. The tubes sit behind homes for weeks or months until they dry, and the work often has to wait for the water to drop.

Riprap

Riprap is heavy rock placed along the slope to armor it. It stands up well to strong waves. It also replaces the lawn with rock, which is hard to walk on, hard to mow around, and tends to collect weeds between the stones.

Sheet pile or seawall

Aluminum sheet pile or a seawall holds the soil back with a vertical edge. Where a bank is too steep for any slope, or a building sits right at the water, it can be the right answer. It changes the look of the lake for good. Waves that hit a hard wall bounce back, and over time they can scour the soil at the base of the wall.

Littoral shelf

A littoral shelf is a shallow ledge planted with water plants. The plants slow waves and runoff before they reach the bank, and many lakes have plantings like this as part of their design. They work best as a partner to a repair, not as a repair on their own. Plants do not rebuild bank that is already gone, and they need ongoing care. Our guide on whether littoral shelves stop erosion explains how they fit.

Rebuilt slope with rooted grass

This is our approach. We rebuild the slope from the waterline up with leading edge technology that lets the grass root into the bank so it holds. The grass grows into the slope instead of sitting on top of it, and the bank gets stronger every year the roots are in the ground. We do not publish how we do it. What residents see is that the work stays at the bank and out of their yards, with no equipment or tubes parked behind their homes for months, and that the finished bank is a lawn to the water.

When a hard edge makes sense

Where a bank is too steep for any slope, or a building sits right at the water, sheet pile or a wall can be the right answer. We will tell you when we see it. Most community lakes have neither problem. They have a grass slope that lost its soil.

Why most communities choose a grass bank

Residents bought a home on a lake with a lawn that runs to the water. A grass bank keeps that look, is easy to mow, and is safe to walk on. The question is how to keep the grass on the slope. A rebuilt slope holds while the grass roots into it. Once the roots take hold, the bank holds itself. And because we keep the work at the bank, residents do not live with equipment or tubes behind their homes while it happens.

At one community in South Florida, we rebuilt about 6,600 feet of bank this way. Residents kept their lawns, and their fences stayed standing. We have also rebuilt the banks of 2 campus lakes at a college in South Florida.

What a board should look at before choosing

Before comparing bids, the board should know 4 things about each section of bank:

• How steep the slope is today, and how steep it was meant to be
• How close homes, fences, pools and pavement are to the water
• Which forces are doing the damage, such as water level swings, runoff, waves or fish nests
• What residents expect to see when the work is done

Those answers narrow the list quickly. A gentle bank with light erosion has more options than a steep bank behind a pool deck. A lake where residents value their lawns rules out rock for most sections. A good contractor should walk every section with you and explain which options fit where, even if some of them are not options that contractor offers.

Questions to ask every contractor

1. Which of the 7 options did you consider for our lake, and why did you pick this one?
2. What holds the bottom of the bank after you leave?
3. What will residents see during the work, and for how long?
4. What does your warranty cover in writing, and for how long?
5. Will you inspect the work after it is finished, and will we get a written report?
6. Do you do the work yourselves, or do you subcontract it?

Ask every bidder the same questions, and give them all the same scope, so the board can compare answers on equal terms.

Common mistakes when comparing options

The first is comparing prices before comparing what each option does. A cheaper repair that comes back in a few wet seasons is not cheaper over the life of the bank. The second is choosing one method for the whole lake when different sections have different problems. The third is treating plantings or dredging as a bank repair. Both have their place, but neither rebuilds soil that is already gone.

How to decide

Start with a record of every section. Our Lake Bank Risk Score gives a quick read on where your lake stands. For the full picture, book a free lake bank walk, where we measure and photograph every section and give the board a written report it can use whether it hires us or not. We then write a scope every bidder can price the same way.

If the board wants to see the result first, we can build a Proof Section of about 100 feet at a spot residents can see, with the fee credited to the full job. The rest of the work is phased by lake. Our work carries a 5 year material and 5 year labor warranty in writing, with inspections in years 3, 5, 7 and 9, each with a written report for the minutes. We do every foot of the work ourselves with no subcontracted crews. Call us at (561) 309 9603.

Questions boards ask

Which lake bank repair lasts the longest?

That depends on the bank. Sheet pile and seawalls are built to last on steep banks or banks next to buildings. On a typical grass slope, a repair that rebuilds the slope from the waterline up and lets the grass root in gets stronger over time instead of weaker.

Are geotubes a good option for HOAs?

They can be on large projects with plenty of sand in the lake. Boards should know that the tubes sit behind homes for weeks or months until they dry, and that the work often waits on low water. Ask the contractor how long the tubes will be visible from each home.

Can littoral plants replace a bank repair?

No. Littoral plants slow waves and runoff, which helps a bank last, but they do not rebuild bank that is already gone. They work best as a partner to a repair.

Can we use different methods on different sections?

Yes, and often that is the right call. A section next to a building may need a hard edge while the rest of the lake keeps a grass bank. A survey of every section shows where each method fits.

Sources: Campbell Property Management, HOA lake bank erosion webinar · Brooks CDDs, lake bank restoration and littorals

More guides

• Why lake banks erode, and how to tell if yours is
• Retention pond bank repair: what boards and managers need to know
• Why regrading and sodding a lake bank does not last