A pierhead line is a legal boundary beyond which artificial structures (such as piers) may not be built into navigable waters. As part of the

Rivers and Harbors Act of 1899 The Rivers and Harbors Appropriation Act of 1899 is the oldest federal environmental law in the United States. The Act makes it a misdemeanor to discharge refuse matter of any kind into the navigable waters, or tributaries thereof, of the United S ...

, the United States federal government may fix pierhead and

bulkhead line Bulkhead line is an officially set line along a shoreline, usually beyond the dry land, to demark a territory allowable to be treated as dry land, to separate the jurisdictions of dry land and water authorities, for construction and riparian activit ...

s as part of its powers to regulate

navigable waters A body of water, such as a river, canal or lake, is navigable if it is deep, wide and calm enough for a water vessel (e.g. boats) to pass safely. Such a navigable water is called a ''waterway'', and is preferably with few obstructions against d ...

. (33 U.S.C.S. § 400, et. seq.) Many states have also established their own pierhead or bulkhead lines at various locations.,Pierhead Line Approval, Wisconsin
/ref>

References

Admiralty law Law of the United States {{US-law-stub