GREAT LAKES BEACHES
AND RISING WATERS
The Army Corps controls lake levels by regulating outflows. While shipping interests prefer
high lake levels to facilitate navigation. Lakefront homeowners prefer low lake levels to constrain
erosion associated with high water.
In recent decades, lake levels have been kept at relatively high levels. Every decade or so, these
higher than average levels have peaked, causing extreme high water episodes in each of the past
three decades. Considerable destruction occurs during these episodes.
Coastal regulators such as the Michigan Department of Environmental Quality continue to endorse
coastal armor such as seawalls and rock revetments as a preferred method of shoreline protection.
Much of the Great Lakes shoreline is consequently so armored. The primary side-effect of coastal
armor is to displace nearshore sand to offshore areas. Long stretches of Great Lakes shorelines
now have no visible beach and little nearshore sand regardless of season or lake levels. Great
Lakes shorelines are now actively eroding even during periods of low water.
As along ocean seaboards, the Army Corps does not acknowledge the widespread erosion
caused by (corps) navigation projects such as harbor structures and dredged and jettied channels.
Nor do state regulatory agencies identify navigation projects as a cause of significant erosion. The
Michigan DEQ, for example, officially emphasizes only high water and storms as contributing to
coastal erosion. Independent experts, however, identify navigation projects as the primary cause of
beach loss on both the Great Lakes and ocean shorelines. Coastal armor, installed largely in
response to erosion caused by navigation projects, is a significant secondary source of coastal
erosion.
Holmberg Technologies and the Michigan DEQ have had a rocky relationship over the years.
Though many of the company's successful beach restoration projects have been permitted by
MDEQ engineers, the company is not permitted to fully deploy its most powerful designs. In
general, state regulators truncate Stabilizer design elements because traditional groins (which take a
right angle approach, as do Stabilizers) have well-known problems.
In general, Great Lakes beaches are more "longshore flow" oriented, in terms of sand source, than
many ocean shorelines (where the primary source of beach sand is often derived from the offshore
shelf rather than longshore sources). Nevertheless, even longshore flow dominated shorelines
benefit when sand transport rates are slowed to something approaching normal rates of longshore
transport. (Unnaturally deepened nearshore waters presently support greater wave and current
energies. Longshore transport rates are consequently increased to the point where the entire
coastal cell erodes abnormally.)
It has proven beneficial to (re)establish progressive resistance along artificially deepened modern
shorelines - whether the shoreline is "longshore" sourced or "offshore" sourced. Extensive
independent monitoring of Stabilizer performance in Great Lakes and ocean settings has
demonstrated that beach growth induced by the system acts as a "feeder beach" to adjacent
shorelines.
Although many coastal experts theorize that sand for Great Lakes beaches is sourced directly from
longshore areas, such as bluff and dune erosion, there are indications that onshore/offshore
exchange is significant (that is, offshore sand, beyond about fifteen feet of depth, contributes to
beach sedimentation). For example, when Stabilizer fields are placed on Great Lakes shorelines,
resulting beach growth generally progrades beyond the seaward ends of the shore perpendicular
system. When such a pattern of progradation occurs in response to shore perpendicular structures,
onshore sand transport is required (Kraus, Hanson, Blomgren, 1994) . (See
The Depth of Closure Hypothesis.)
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