Erosion, Avulsion, and a New Fence
Lot 6 fronts 620 ft on Mill Creek, a non-navigable stream. The 1948 deed runs 'thence to the thread of Mill Creek,' and the deed recites 8.62 acres. The 1948 survey placed the thread 180 ft north of the north lot line as monumented. Between 1990 and 2014 the north bank retreated landward at roughly 0.6 ft per year; the owner accepted the loss without complaint and no one surveyed it. In March 2015 a single storm cut a new channel 32 ft landward in under 36 hours, abandoning the old channel as a dry slough. The adjoining owner has since fenced to the new channel and now claims the whole strip - about 46 ft wide by 620 ft, roughly 0.65 acre. Your client wants the 1948 thread 'surveyed back' and asks you to stake it.
1. Locate the boundary. Treat the two events separately and give the number.
Read the worked answer
Two events, two rules.
- 1990–2014, gradual retreat of 0.6 ft/yr. Slow, imperceptible movement of a non-navigable stream is accretion/erosion: the boundary moves with the stream and the riparian owner loses. 24 years x 0.6 = 14.4 ft lost, 14.4 x 620 = 8,928 sf = 0.205 ac.
- March 2015, 32 ft in 36 hours. Sudden and visible - that is avulsion. An avulsion does not move the boundary. The boundary stays at the thread as it existed immediately before the storm, and the 32-ft strip (32 x 620 = 19,840 sf = 0.455 ac) remains your client's, even though it is now on the far side of the new channel.
Boundary location: 14.4 ft landward of the 1948 thread - not 46.4 ft landward, and not the 1948 line.
Area: roughly 8.62 − 0.205 ≈ 8.42 ac, subject to the geometry at the ends of the frontage.
Tell the client plainly: 'surveying it back' to 1948 would take 0.205 ac he has already lost by erosion. The dispute is over the 32-ft strip, not the whole 46.4 ft.
2. The adjoiner's new fence sits on the new channel bank. How do you depict it, and what evidence will decide the avulsion question?
Read the worked answer
Depiction - show four things, not one:
- The record line as described (the 1948 thread position) and its source.
- The boundary as you have located it (14.4 ft landward of the record thread).
- The abandoned channel and the new channel, both drawn and labeled.
- The adjoiner's fence as a line of possession, annotated as a claim, with the area in dispute called out (~0.455 ac).
Do not set the boundary at the fence, and do not set it at the new channel. The plat shows your location and identifies the conflicting evidence so a court can rule on it.
Evidence that decides avulsion versus erosion:
- Pre- and post-March-2015 aerial or satellite imagery, ideally within weeks on each side of the event.
- The 2015 flood and precipitation record; gauge data if available.
- Historical aerials from 1990 through 2014 showing the slow creep - this establishes the erosion component and its amount.
- The 1948 survey and plat showing the then-thread, plus any earlier meander line.
- Witness statements about the storm and about where the water ran before and after.
Without the historical imagery you cannot separate the 14.4 ft from the 32 ft, and the case collapses into 'the fence is where it is.'
3. The client asks you to certify 8.62 acres because 'that is what the deed says.' How do you respond?
Read the worked answer
No. The deed does not guarantee area, and the creek took some of it.
- The 8.62-acre figure is a recital; the boundary is the call 'to the thread of Mill Creek,' and the thread has moved. Erosion between 1990 and 2014 cost roughly 0.205 ac and that loss is real regardless of what the deed says.
- Certifying 8.62 ac would misstate the parcel to a lender or buyer and would be indefensible if the avulsion strip is later litigated. You would be sealing a number you know to be wrong.
- What you can certify: the monumented north and side lines, the located boundary, the computed area, and the area in dispute - each labeled for what it is.
- Recommend counsel for the avulsion claim and, if title is to be insured, a title company aware of the dispute. Your product is a defensible location of a boundary and a disclosure of the conflict, not a resolution of it.