Wyo. Stat. § 18-5-319 (2026)

(a) Each subdivider seeking to create or divide a
subdivision that is adjacent to lands upon which livestock can
be legally run at large shall comply with all of the following:

          (i) The subdivider shall be responsible for the
construction of a perimeter fence on any part of the subdivision
that is adjacent to lands upon which livestock can be legally
run at large unless a legal perimeter fence already exists at
that location or all adjacent landowners' consent that a
perimeter fence is not necessary;

          (ii) The perimeter fence required under this
subsection shall be a lawful fence as prescribed by W.S. 11-28-
102;

          (iii) The subdivider shall be responsible for all
costs of the original construction for the perimeter fence.
     (b) Upon completion of the construction of a perimeter
fence required under this section, the subsequent landowner or,
if the subdivided parcel has not been sold, the subdivider
shall:

          (i) Be responsible for the costs of maintaining the
perimeter fence provided that the adjoining landowner shall be
responsible for half of the costs of maintaining the perimeter
fence, not to exceed the reasonable costs to maintain the fence
if the fence was a fence under W.S. 11-28-102(a)(i);

          (ii) Not be liable for any damage caused by or
arising from livestock pastured on adjoining land that may
breach the perimeter fence and wander on the subdivided land,
provided that the perimeter fence is maintained in accordance
with this section.

     (c) The adjoining landowner shall not be liable for any
damages caused by, or arising from, livestock pastured on the
adjoining land that may wander onto the subdivided land except
as provided in W.S. 11-28-108.

     (d) Before receiving a subdivision permit under this
article, a subdivider shall provide information and evidence of
the construction or plans to construct any perimeter fence
required by this section in accordance with W.S. 18-5-
306(a)(xiii).