Lakefront Shoreline Erosion: What Riprap Does

Lakefront property loses ground quietly. A few inches a season from wave action and runoff does not look like much until the lawn edge is undercut and the bank is dropping into the water in chunks.

What causes shoreline erosion here

Three forces do most of the damage. Boat wake and wind-driven waves work at the waterline, lake level fluctuation repeatedly saturates and drains the bank, and stormwater runoff from the property above cuts into it from behind.

The runoff piece is the one owners control most directly and overlook most often. Water that sheets off a driveway, roof, or lawn and concentrates at the top of the bank erodes it far faster than the lake alone.

Bare soil accelerates everything. Once turf or vegetation gives way at the water's edge, each cycle takes more material.

What riprap does

Riprap is graded stone placed along the bank to absorb wave energy that would otherwise strike bare soil. Water moves into the voids between stones and loses force instead of carrying soil away.

A proper installation is not a pile of rock. It involves shaping the bank to a stable slope, placing a filter layer or geotextile so soil cannot wash out through the stone, and using a stone size and depth appropriate to the exposure.

Done well, riprap looks like a natural stone edge and needs very little attention. Done as loose rock dumped on a steep bank, it slides, settles, and lets erosion continue behind it.

Other stabilization approaches

Riprap is one option among several, and the right answer depends on the bank's slope, exposure, and how you use the shoreline.

• Vegetated buffers — deep-rooted plantings that hold soil and slow runoff, often used with or instead of stone on gentler banks.
• Bioengineering approaches that combine stone at the waterline with plantings above it.
• Regrading the bank to a stable slope, which is sometimes most of the fix.
• Upland drainage work so runoff never reaches the bank as concentrated flow.

Handle the upland water first

Shoreline work that ignores the water coming down the property tends to be undone from the land side. Before stone goes in, roof and driveway runoff should have a controlled path that does not discharge over the top of the bank.

That usually means piped downspouts, a swale that spreads flow, or a stone-lined channel with an outlet designed for the volume — the same logic behind a dry creek bed.

Slowing and spreading water is the whole goal. Concentrated flow is what carves banks; diffuse flow is what grass and stone can handle.

Approvals and the shoreline boundary

Work at the water's edge is not the same as work in your backyard. Lake Norman's shoreline is managed, and shoreline stabilization typically requires review and written authorization before any material is placed.

Requirements vary by the specific location and the type of work proposed, so confirm the current process with the lake's shoreline management program and your local jurisdiction before scheduling anything.

Southern Style Turf & Design handles erosion control and the upland drainage that feeds shoreline problems for properties around Lake Norman, and will tell you when a project needs approvals before it needs a crew.

Helpful outside reference

North Carolina's rules for disturbed soil are explained by the NC DEQ erosion and sediment control program.

Frequently asked questions