Wyo. Stat. § 35-11-904 (2026)

(a) Except as provided in subsection (c) of this section,
any person having an interest which is or may be adversely
affected, may commence a civil action on his own behalf to
compel compliance with this act only to the extent that such
action could have been brought in federal district court under
Section 520 of P.L. 95-87, as that law is worded on August 3,
1977:

          (i) Against any governmental entity, for alleged
violations of any provisions of this act or of any rule,
regulation, order or permit issued pursuant thereto, or against
any other person for alleged violations of any rule, regulation,
order or permit issued pursuant to this act; or

          (ii) Against the state of Wyoming, department of
environmental quality, for alleged failure of the department to
perform any act or duty under this act which is not
discretionary with the department.

     (b) Actions against the state of Wyoming, department of
environmental quality, pursuant to this section shall be filed
in the district court for Laramie county. Actions against any
governmental entity, or any other person pursuant to this
section shall be filed in the district court for the county in
which the violation is alleged to have occurred.

    (c)   No action pursuant to this section may be commenced:

          (i) Prior to sixty (60) days after the plaintiff has
given notice in writing of the violation and of his intent to
commence the civil action to the department and the alleged
violator, except that such action may be brought immediately
after such notification if the violation complained of
constitutes an imminent threat to the health or safety of the
plaintiff or would immediately affect a legal interest of the
plaintiff; or

          (ii) If the department, through the attorney general,
has commenced a civil action to require compliance with the
provisions of this act, or any rule, regulation, order or permit
issued pursuant to this act, but in any such action any person
may intervene as a matter of right.

     (d) The state of Wyoming, department of environmental
quality, may intervene as a matter of right in any action filed
pursuant to this section.

     (e) The court, in issuing any final order in any action
brought pursuant to this section, may award costs of litigation,
(including attorney and expert witness fees), to any party
whenever the court determines such award is appropriate.

     (f) The availability of judicial review established
pursuant to W.S. 16-3-114 shall not be construed to limit the
operation of rights established in this section.

     (g) Nothing in this act shall in any way limit any
existing civil or criminal remedy for any wrongful action
arising out of a violation of any provision of this act or any
rule, regulation, standard, permit, license, or variance or
order adopted hereunder.