The jurisdictional threshold of admiralty courts in navigable waters is set on the ordinary high watermark.  However, if navigation is made temporarily possible by the rising of water level by flood, it will not attribute jurisdiction to such waters.  Man-made waterways and reservoirs are considered to be navigable waters for the purpose of admiralty law, provided such waterway is used or is “susceptible of being used as an interstate highway for commerce over which trade or travel is or may be conducted in customary modes of travel on water.”

The real test of navigability is the capability of use of a water body by the public for purposes of transportation and commerce, rather than the extent and manner of that use.  Thus, a lake meets the requirement that it be an interstate highway for commerce for purposes of admiralty jurisdiction if it straddles two states, thus satisfying the interstate nexus component of admiralty jurisdiction.  If the inter-state nexus is established, the fact that maritime traffic on the lake is prevented from traveling downstream by a lockless dam is not deemed to be probative.[i]

It is to be noted that admiralty law does not apply to accidents which occur on offshore petroleum platforms.[ii]  This is because offshore petroleum platforms are artificial islands, and hence accidents occurring on such islands do not fall under admiralty court’s jurisdiction.[iii]  Further, admiralty jurisdiction does not extend to accidents on piers, jetties, bridges, or even ramps or railways running into the sea.  “To the extent that it has been applied to fixed structures completely surrounded by water, this has usually involved collision with a ship and has been explained by the use of the structure solely or principally as a navigational aid.  But when the damage is caused by a vessel admittedly in admiralty jurisdiction, the Admiralty Extension Act would now make available the admiralty remedy in any event.”[iv]  Similarly, drilling platforms does not come under admiralty jurisdiction.

[i] Finneseth v. Carter, 712 F.2d 1041, 1044 (6th Cir. Ky. 1983)

[ii] Terry v. Raymond International, Inc., 658 F.2d 398, 405 (5th Cir. La. 1981)

[iii] Rodrigue v. Aetna Casualty & Surety Co., 395 U.S. 352 (U.S. 1969)

[iv] Id.