Accretion, Avulsion, and a Creek That Moved Overnight
An 11.5-acre parcel in Hunterdon County is described in a 1902 deed as running 'to the bank of the creek, thence down the creek'. A survey shows an old stone wall and fence line along the bank as it existed before 2011. In August 2011, flooding cut a new channel across the owner's lower meadow, moving the low-water line roughly 22 ft south overnight and leaving a gravel bar where the old channel ran; the old channel now carries water only at high flow. Comparison of 1998, 2007 and 2012 orthophotos shows the bank had also crept north at about 1.2 ft per year between 1998 and 2007. The owner has planted grass to the new channel and wants the parcel area increased accordingly. The downstream neighbor objects and has threatened to remove a gate. The creek is not tidal and not navigable.
1. Classify each of the two bank movements and state where the boundary lies today.
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Two different doctrines.
1998–2007 movement (about 1.2 ft/yr). Gradual, imperceptible change is accretion. Where a deed bounds on a natural watercourse, the boundary moves with the water as it shifts by accretion; the riparian owner gains or loses without any conveyance. This movement favors the owner and is the easier half of the problem.
August 2011 movement (about 22 ft overnight). A sudden, perceptible shift of the channel during a flood is avulsion. The established rule is that avulsion does not move the boundary: the boundary remains where the bank or thread was immediately before the event, even though the water now runs elsewhere. The owner does not gain the 22 ft, and the abandoned channel does not become the neighbor's land. The gravel bar is not a boundary change.
Where the boundary is. At the position of the bank as it stood just before the 2011 flood - that is, the bank after the gradual accretion through 2007, still evidenced by the stone wall and fence and by the pre-flood aerial photography. Not at the current channel, and not at the 1902 line.
Deed language matters. This deed runs 'to the bank', not 'to the thread of the stream', so the bank is the call; on a non-tidal, non-navigable creek there is no public-trust overlay to complicate the analysis. If the stream were tidal or navigable, mean high water and a different set of rules would govern.
2. What evidence would you gather, and how would you depict the result on the survey without overstepping the surveyor's role?
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Evidence to assemble.
- Dated aerial imagery spanning the period, with flight dates, especially any pre- and post-2011 coverage.
- Flood records: gage data, high-water marks, newspaper and emergency-management accounts of the 2011 event, to establish suddenness.
- Any pre-2011 survey, topo, or engineering plan showing the bank in position.
- Field evidence: the stone wall and fence line, bank scarps, vegetation age and species on the gravel bar versus the established bank, soil profiles in a shallow probe.
- Witness statements from the owners about what they saw and when.
- Cross sections across both the old channel and the new one, so the geometry is documented rather than asserted.
Depiction. Show the pre-avulsion bank position as the boundary of record, tied to the stone wall and to the aerial evidence, with coordinates and a clear note of the basis (accretion through 2010; avulsion August 2011). Show the present channel and the old channel as physical evidence, labeled as such. Do not stake or monument the new channel as a boundary.
Role limits. The surveyor locates and documents; the legal effect of accretion and avulsion, and the ownership of the abandoned bed, is for counsel. State the findings neutrally, deliver the same package to both owners, and recommend that the parties obtain a legal opinion or a recorded agreement rather than resolving it at the gate.