Lake Michigan Seawall Inspection: The Summer Checklist That Catches Failures While They Are Still Cheap

Published July 20, 2026 by Lake Michigan Seawalls

Summer is when Lake Michigan lets you look. The ice is long gone, the water is warm enough to wade, and the wall that spent January taking ice shove and November taking gales is standing quietly in front of you. Every failure we get called to in October was visible in July to someone who knew where to look. This is the walk-through we do on our own assessments, in the order we do it, written for a lakefront owner with an hour and a pair of water shoes.

The timing argument got stronger this year. Per the Army Corps of Engineers' July 2026 update, Lake Michigan-Huron is running a couple inches above its long-term July average and noticeably higher than it stood a year ago. Rising water re-tests every wall that got a pass during the lower years. The joints, scour pockets, and tired anchors that did not matter at last summer's levels are back in the fight.

Start Behind the Wall, Not in Front of It

Most owners inspect a seawall by standing on the beach and looking at the face. The wall fails from behind. Walk the ground within ten feet of the landward side first and read the surface.

Depressions and sinkholes. Any dip, hollow, or open hole in the lawn or backfill behind the wall means soil is leaving. It exits through open joints, corrosion holes, or under a scoured toe, one wave cycle at a time, and the surface slumps into the void it leaves. A sinkhole is the single most misread seawall symptom on the lake because it looks like a landscaping problem. It is a structural one, and it is the wall telling you exactly where it is leaking soil.

Cracked or tilted cap. Sight down the concrete cap from one end. It should run straight and level. New cracking, sections rotating toward the lake, or a cap pulling away from the panels below it are movement, recorded in concrete. Hairline shrinkage cracks in old concrete are normal. A crack that is opening year over year is not.

Vegetation lines and wet spots. A stripe of lush growth or persistent wet soil behind one wall section often marks trapped water, which means the drainage there has stopped doing its job. Note it; it will match what you find at the weep holes.

Read the Wall Face for Movement

Stand at one end of the wall and sight down its length like a fence line. Steel, vinyl, and concrete walls are all built straight; the lake bends them. Any bow, belly, or lean toward the water is load winning against structure. On anchored walls, lean almost always means the tie rod or deadman is failing, a system we broke down in our guide to seawall tiebacks and deadman anchors. A wall can lose most of its anchoring capacity and still look fine face-on. The sight line is what gives it away.

While you are there, check the joints. Sheet pile interlocks and vinyl panel seams should be tight. Daylight through a joint, or a vertical stripe of escaped sand on the lake side of one seam, is a soil-loss path, and it explains the depression you found behind the wall a few minutes ago.

The Waterline: Corrosion's Favorite Elevation

On steel sheet pile, the splash zone at and just above the waterline corrodes fastest. It is wet, oxygenated, and worked by every wave. Look for the horizontal band of heavy scale, flaking, and pitting. Surface rust on steel is expected and mostly harmless. Deep pitting, holes you can push a screwdriver through, or a visible thinning band at water level is section loss, and section loss at the waterline is where sheet pile walls break their backs. Vinyl does not rust, but check it for UV chalking, impact cracks from ice, and split seams; our material comparison covers how each product ages on this lake.

Weep Holes: The Cheapest Thing You Will Ever Fix

Find the weep holes, the drainage openings low on the wall face, and check that they are open and, after a rain, flowing. Water builds in the soil behind every wall, and those holes are what keep hydrostatic pressure from loading the wall like a second lake pushing from the land side. Silted, buried, or vegetated weep holes put pressure on the structure that it was never designed to carry alone. We wrote a full piece on seawall drainage and hydrostatic pressure because clogged drainage quietly causes more wall damage on Lake Michigan than waves get blamed for. Clearing weep holes is an afternoon job. The bulge that develops when they stay clogged is not.

Get Wet: Check the Toe

The toe, where the wall meets the lakebed, is the finding most inspections skip because it means getting in the water. Summer's calm and clarity make July the right time. Wade the face and feel along the base with your feet or a probe rod.

• Scour trench. A trough carved along the base means waves are excavating the lakebed that braces the wall. As the trench deepens, the wall's effective embedment shrinks and the structure starts working as a taller wall than it was designed to be.
• Exposed sheet bottoms. If you can feel the bottom edge of the sheet pile, embedment is gone at that spot and undermining is underway. Soil from behind the wall will follow the water out through that gap.
• Migrating stone. On walls fronted by riprap or toe stone, note where stone has rolled away or sunk. Toe stone is sacrificial protection, and thin spots are where next winter's scour will concentrate.

Check the Ends

Walk to each end of the wall and look at where it ties into the neighbor's protection or the natural bank. Erosion accelerates around the ends of a wall, a process called flanking, and a wall that ends short of stable ground gets outflanked from behind. A growing notch of erosion at either end will eventually let the lake in behind the entire structure, no matter how sound the face is. End returns and transitions to adjacent walls are engineering details, and they are a common gap on older owner-built walls.

What the Findings Mean

Scoring what you found: open weep holes, tight joints, straight sight line, sound toe means you are done in an hour and your wall goes back to being landscape. Clogged drainage, early toe scour, or isolated cap damage are maintenance items, fixable this season for modest money. Movement, sinkholes, active soil loss, or waterline section loss are engineering items, and the honest math on those lives in our guide to seawall repair vs replacement. The pattern in all of it: walls almost never fail suddenly. They fail on a schedule, visibly, with years of notice for anyone who walks the wall each July. Winter is what turns a finding into a failure, and ice does not negotiate.

Frequently Asked Questions

How often should a Lake Michigan seawall be inspected?

Walk it twice a year at minimum: once in early summer after ice-out and spring storms have done their damage, and once in fall before ice season. Add a check after any major storm with sustained onshore winds. A formal engineered assessment every few years, or immediately when you find lean, sinkholes, or toe scour, catches what a walk-by cannot.

What is the most serious warning sign on a seawall?

Movement. A wall that is leaning toward the water, a cap line that no longer sights straight, or a new gap opening between panels means the structure is losing its fight with the soil and water behind it. Movement usually traces to a corroded tieback, failed drainage, or toe scour, and it gets more expensive every season it is ignored.

What causes sinkholes behind a seawall?

Soil is escaping through or under the wall. Open joints, corrosion holes, or a scoured toe let waves pull backfill out grain by grain, and the surface eventually collapses into the void. A depression or sinkhole behind the wall is never cosmetic. The ground you see missing is the soil that was holding the wall and your lawn in place.

Why do weep holes matter on a Lake Michigan seawall?

Weep holes relieve the water pressure that builds in the soil behind the wall after rain and during high lake levels. When they clog, hydrostatic pressure loads the wall from the land side, which is how walls crack, bulge, and tip outward. Flowing weep holes after a rain are a good sign. Silted, buried, or dry ones on a wet bank are not.

Can a damaged seawall be repaired, or does it need replacement?

It depends on what failed and how far it has gone. Clogged drainage, isolated cap damage, early toe scour, and a corroded tieback on an otherwise sound wall are all repairable. Widespread corrosion at the waterline, failed embedment, or a wall that has rotated significantly usually points to replacement. An engineered assessment tells you which side of the line you are on.