White Paper · Best Practices

Sand Fence Best Practices for Lake Huron Shoreline Homes

Thumb Fence Co. · Port Austin, Michigan · September 2026 · Version 1.0

Every fall, homeowners from Caseville to Port Hope put up a roll of snow fence on the beach and hope. Some of those fences work. Many do not, and the reasons are not mysterious. Coastal engineers have measured how wind moves sand and how porous fences catch it for more than eighty years. This paper collects what that research says, adds what the public wind records show for the Thumb, and turns both into a set of practices anyone can apply. Where the science is thin or we are inferring, we say so.

1. The short version

• A few strong days move the sand, not the average breeze. Sand transport rises with the cube of wind speed. On the Great Lakes, most of the year's sand moves in fall and winter storms, after the beach grass dies back and before the shore ice forms.
• On the Thumb, the everyday wind and the sand-moving wind are different winds. The common wind is west to southwest. The strong wind on Saginaw Bay shores is west to northwest. On the east shore at Harbor Beach the strong wind comes off the lake from the north and south-southeast.
• Sand travels along the beach more than straight in from the water. A wind blowing at an angle sees a longer runway of dry sand, and on a typical lakefront lot that runway is what limits how much sand moves.
• How open the fence is decides which side the sand lands on. A fence about half open drops its sand on the downwind side, with the crest one to two fence heights past the fence. A fence under a third open piles sand on the windward face and acts like a wall.
• A fence starves everything downwind of it. That is the whole point when you want to protect a yard, and the whole problem when the thing downwind is a dune you wanted to keep.
• Length beats cleverness. The catch tapers off about twelve fence heights from each end, so a short run is mostly ends. Straight, zig-zag or V layouts caught about the same sand in field trials. Gaps cost more than any layout choice gains.
• Square to the wind, within 25 degrees, is good enough. Beyond 45 degrees the fence stops working well.

2. How wind moves sand

Threshold and the cube law

Dry beach sand does not move until the wind at head height reaches roughly 12 to 15 miles per hour. Below that, nothing happens. Above it, the grains bounce along the surface in a layer a foot or two deep, and the amount moved rises with the cube of the wind speed. Doubling the wind above threshold moves six to eight times as much sand. The classic relations come from Bagnold in 1941 and were confirmed on real beaches by Kubota, Horikawa and Hotta in 1982 and recalibrated by Sherman and colleagues in 2013 [1, 2, 3].

The cube law is why the wind rose on a weather site can mislead you. The wind that blows most often is usually light. The wind that moves your sand blows a few days a year. At Mount Baldy on Lake Michigan, most of the annual transport happened in fall and winter gales above 40 miles per hour, and one storm at the end of October 2013 moved about a quarter of the year's total [4]. Across eleven Lake Michigan shore stations in 2015, every one of 83 sand-moving events was tied to a passing storm system [5].

Angle and runway

Two things fight each other when wind crosses a beach at an angle. The sand delivered to each foot of shoreline falls off with the cosine of the angle, so a wind blowing straight along the beach delivers nothing to the dune line. But moving sand needs distance to build up, and a wind at an angle has a longer runway across the same width of beach. Bauer and Davidson-Arnott laid out this framework in 2003 [6]. The runway needed to reach full transport, called the critical fetch, has been measured on real beaches at anywhere from about 30 feet in light wind to several hundred feet in strong wind or on damp sand [7]. A lakefront lot with 50 to 100 feet of dry sand is almost always runway-limited. On a narrow Delaware Bay beach, one storm blowing 63 degrees off square caught more than twenty times the sand of any straight-onshore storm, including faster ones, because its runway was twice as long [8].

What shuts it off

• Wet sand. Moisture raises the threshold, but once grains are bouncing they keep the surface moving even at ten percent moisture. Rain and drying make transport come and go by the hour.
• Frozen sand. On a cold-climate dune the threshold rose through fall, peaked in midwinter when the pore water froze, and swung by more than 10 miles per hour in two hours as the surface thawed [9].
• Season. Summer is maximum grass and minimum wind. Fall storms plus dying vegetation give the peak. Shore ice and snow shut it down, and the spring thaw releases what was stored [10].
• Lake level. Beaches widen in low-water years and drown in high-water years. Lake Michigan-Huron rose almost nine feet from January 2013 to September 2020 and destroyed foredunes along the Michigan shore [11, 12]. It has since fallen below its long-term average, which means the beaches are wide again and more dry sand is exposed to the fall wind than at any time since 2015.

3. Which winds matter on the Thumb

No one has published a sand transport study for Saginaw Bay or the Thumb shoreline. What we can do is read the public wind records with the cube law in mind. The table below is our own summary of raw observations from three National Weather Service and NOAA stations and one offshore buoy [13, 14]. It is not a published climatology.

The pattern is the same everywhere. The frequent wind is west to southwest. The energetic wind, the one that moves sand, is west to northwest in fall and winter over the open lake, and north or south-southeast at a shoreline station facing the lake. The Ontario shoreline plan for the far side of the lake reaches the same conclusion from a thirty-year wave record: northwest storms dominate and the net sand drift runs south [15].

4. What a porous fence does

A fence does not stop sand. It slows the wind enough that the wind drops what it is carrying. Where the sand lands depends on three things: how open the fence is, how tall it is, and how the wind hits it.

Openness decides the side

Hotta and Horikawa ran beach sand through fences of every porosity in a wind tunnel. Fences 0 to 30 percent open piled sand on the windward face. Fences 40 to 50 percent open dropped it on the lee side, with a dune forming right behind the fence. Forty percent trapped the most sand fastest. Nearly all the sand landed within ten fence heights of the fence [16]. A 2022 tunnel study confirmed the switch near 30 percent and put the crest about two fence heights downwind [17]. Below about 20 percent open the fence deflects sand along its face instead of catching it [18]. The reason, from computational studies, is that a fence around half open shelters the ground without spinning up the strong eddy on the lee side that scours sand back out [19]. Field trials on the Outer Banks measured the catch rising steadily as fabric went from over 80 percent open down to 40 percent, with standard 50 percent wood slat fence catching about 2.8 cubic yards per foot [20].

Height caps the pile and burial ends the fence

The finished pile tops out at roughly 0.8 to 1.2 times the fence height [21]. The fence effectively stops working once it is buried to about 80 percent of its height [16]. The volume a fence can hold rises with the square of its height, so one 6-foot fence stores as much as two 4-foot rows. The Army Corps' Shore Protection Manual says a 4-foot fence at 50 percent open usually fills within a year to about its own height and holds two to three cubic yards per foot [22]. Michigan's own best-practice sheet says to add the next row when the first is two-thirds buried [23].

Downwind starvation

Hotta and Horikawa also saw the surface lose sand beyond about fifteen fence heights downwind, because the fence intercepted the supply [16]. Twenty years of laser mapping on the North Carolina coast confirmed it at full scale: the natural dunes landward of fenced dunes were shorter, wider and smaller because the fences cut off their sand [24]. This is the property that makes a fence useful for keeping sand off a yard, and the property to respect when the thing downwind is a dune you want to keep.

Angle

The only source with explicit numbers on orientation is Tabler's snow-fence guidance, which grew out of decades of Wyoming highway work and transfers well to blowing sand [25, 26]. Departures up to 25 degrees from square to the wind do not affect performance. Beyond 45 degrees the catch falls, and a slat fence gets effectively less porous as the wind turns oblique, while a corkscrew flow along the fence bleeds material out the downwind end. In practice most beach fences are set parallel to the shore regardless, with short spurs at 45 or 90 degrees to catch the cross-wind [18].

Length, ends and gaps

The drift rounds inward about twelve fence heights from each end, so a fence needs to be 25 to 30 fence heights long to reach full storage in its middle [25]. For a 4-foot fence that is 100 to 120 feet. Two field trials compared straight fences against zig-zag, V and spur layouts. Neither found a layout that caught more sand, and one found fence length was the only thing that mattered [27, 28]. The advantage of a zig-zag is a wider, more natural-looking dune, not more sand. Gaps are a different story. Tabler's finding is blunt: even a small opening significantly reduces storage capacity [26].

5. Decide the goal first

The same fence placed in two different spots does two opposite jobs. Decide which one you want before the first post goes in.

The narrow-beach case deserves a straight answer. Hotta and Horikawa found that a fence 15 to 20 fence heights upwind of a wall minimized the sand passing over it. A 4-foot fence on a 30-foot beach cannot be placed at that ratio. A 2-foot fence can, but it holds a quarter of the sand. Neither choice is wrong. The homeowner just needs to know which trade they are making. That trade-off is an inference from the published ratios, not a result anyone has tested on a Lake Huron beach.

6. The practices

7. Rules and permits in Michigan

This section summarizes public state guidance. It is not legal advice, and shoreline rules change. Confirm with the Michigan Department of Environment, Great Lakes, and Energy (EGLE) district office before building anything permanent.

• Critical dune areas. EGLE policy lists placement of a temporary snow or sand fence, and open fences installed with hand tools that follow the grade, as activities that do not need a permit under Part 353 [33]. Removing newly wind-blown sand from a driveway or structure is also allowed, provided it is not dumped below the high water mark. Whether any designated critical dune area lies in Huron County is not something we have confirmed.
• Bottomlands. Below the 580.5-foot ordinary high water mark, structures need a joint EGLE and Army Corps permit under Part 325 [30, 34]. The 2012 beach grooming exemption covers leveling, grooming and hand removal of vegetation. It does not mention fences. We have found no state document that addresses a temporary fence below the line, so the simple answer is to stay above it.
• State best practice. EGLE's sand dune stabilization sheet says to install fence as far landward as possible and out of reach of storm waves, never to aim collected sand at a building, and to plant beach grass landward of the fence [23].

8. What we do not know

We will update this paper as we measure our own fence lines through the winter. If you have a fence that worked, or one that did not, we would like to hear where it was and what the wind did to it.

9. References

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