The hook
Boundaries that touch water follow rules that are centuries old and highly state-specific. Riparian (rivers / streams), littoral (lakes / oceans), navigable vs. non-navigable, accretion vs. avulsion, the public trust doctrine. A surveyor who guesses on water boundaries gets sued.
| Concept | Slow change | Sudden change |
|---|---|---|
| Term | Accretion (gain) / Erosion (loss) | Avulsion |
| Boundary moves with water? | YES — riparian owner gains/loses | NO — boundary stays at original line |
| Common cause | Gradual silt deposit; gradual recession | Flood cuts new channel; landslide |
| Reliction | Slow recession exposing land — boundary follows | — |
Memorize these
Concepts that show up on the exam
Riparian rights
Rights of an owner whose land touches a flowing watercourse. Includes access, water use, and ownership to the OHWM (or thread of stream, depending on navigability).
Littoral rights
Rights of an owner whose land touches a non-flowing body (lake, ocean). Similar in concept to riparian.
Navigable waters
Federal: usable for commerce. State courts may extend the definition for state-law purposes. Bed of navigable waters is owned by the STATE (sovereign land); private ownership stops at the OHWM.
Ordinary high water mark (OHWM)
The line on the bank reached by ordinary (not flood) high water. Identifiable by physical evidence: vegetation change, soil characteristics, debris line.
Thread of stream
The geometric centerline of a watercourse. On non-navigable streams, riparian owners often own to the thread.
Public trust doctrine
The public retains rights to navigation, fishing, recreation in navigable waters even when the bordering land is private.
Test yourself
How well did it stick?
A quick 5-question check on Water Law. See where you stand and what to review.