Harbor Dredging

Background
Just as highways require maintenance and repaving, shipping channels require maintenance as well.  Such maintenance takes the form of periodic dredging to remove sand and silt that naturally accumulate.  By removing this material, the channel is kept clear of obstructions, allowing ships to navigate into a port.

By law, the U.S. Army Corps of Engineers is responsible for conducting maintenance dredging throughout the United States.  Money for this work is included in the Corps' annual budget.  Unfortunately, due to budgetary constraints, the Corps' has not had adequate funds to dredge the nation's harbors. Great Lakes harbors have been particularly underfunded.

The consequence of underfunding maintenance dredging is that harbors become choked with sand or silt and become unusable. Today, numerous ports in the Great Lakes are experiencing a dredging crisis.

Navigation Channels
The major shipping channels in every port have been authorized in legislation enacted by Congress at some time in the past.  These authorizations specify the depth, width, and geographic configuration of underwater navigation channels.  These authorizations guide the Corps of Engineers in determining what must be dredged when a harbor is first built, and later what must be dredged to maintain that harbor.

Also within a harbor are "secondary channels" that branch off the main, federal channel.  These secondary channels provide ships access from the main channel to private docks.  Typically the dredging of secondary channels is the responsibility of the dock owner.  In some cases, the dock owner might be a private company, or a public entity like a port authority or city government.

Beyond the harbors, the Great Lakes include several "connecting channels" that enable ships to move from one lake to another.  For example, in northern Michigan there is a navigation channel in the St. Marys River, which connects Lake Superior to Lake Huron.  Likewise, there is a navigation channel in the St. Clair River and Detroit River, which connect Lake Huron to Lake Erie.

Maintenance Dredging
After a federal navigation channel is first constructed (dredged), it must be maintained by periodic maintenance dredging.  The amount of maintenance dredging required depends upon local natural conditions such as weather, currents, water levels, erosion, etc.

Financing of Maintenance Dredging
For Great Lakes and coastal harbors, the Army Corps of Engineers' maintenance dredging program is financed through a port user fee - the "Harbor Maintenance Tax."
Harbor Maintenance Tax receipts are placed in the federal Harbor Maintenance Trust Fund, which serves as a source of revenue for the Army Corps of Engineers' dredging budget.  Unfortunately, there is no direct link between the inflow of tax revenue to the federal government and the outflow of dredging funds.
Tax collections are determined by the volume of trade, which has grown over the last two decades.  Expenditures are determined by the Congressional budget and appropriations process.  With tax collections growing and budgetary pressures constraining spending, the Harbor Maintenance Trust Fund has accumulated an excess balance of more than $3.3 billion (as of Fiscal Year 2007).

Great Lakes Dredging Needs
Due to budgetary constraints, in recent years the Corps of Engineers has been unable to properly dredge many Great Lakes harbors.  In 2006, the Great Lakes Maritime Task Force, a shipping industry advocacy group, declared a "Great Lakes dredging crisis," noting that the backlog of Great Lakes dredging projects now totals roughly $250 million.

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