[¶ 1] John Max Stutzman and Roberta Lee Stutzman (the Stutzmans) requested the Wyoming State Engineer’s Office (state engineer) to file federal land patents pursuant to Wyo. Stat. Ann. § 41-3-324 (LexisNexis 2005). The state engineer denied the request, stating the land patents were not deeds for reservoir water subject to the statute and, therefore, the state engineer’s office could not record them. The Stutzmans filed a petition for review in district court claiming the state engineer unlawfully withheld agency action. The district court denied the petition, holding the issue was governed by
In re Big Horn River System,
ISSUES
[¶ 2] The Stutzmans present the following issues:
1. Is filing of the offered land patents under Wyoming Statute § 41-3-324 precluded by the Court’s decision in In re Big Horn River System,85 P.3d 981 (Wyo.200[4])?
2. Whether the land patents delivered to the state engineer for filing pursuant to Wyoming Statute § 41-3-324 are deeds for reservoir water and water rights.
The state engineer states the issues as follows:
I. Did the District Court accurately conclude that agency action was not unlawfully withheld because the holding in In re Big Horn River System,2004 WY 21 ,85 P.3d 981 (Wyo.200[4]), forecloses the Stutzmans’ state law water right claim?
II. As a matter of state law, do the federal land patents the Stutzmans submitted for filing as reservoir water deeds with the State Engineer’s Office qualify as valid deeds?
FACTS
[¶ 3] This case arises from the same facts as
Big Horn,
[¶ 4] The rights to the waters of the Big Horn River have been the subject of extensive adjudication encompassing three separate phases. For a detailed summary of the factual and legal background of the adjudication, see
Big Horn,
[¶ 5] On January 4, 2001, three years after the entire adjudication was scheduled to be completed, the Stutzmans filed a petition to intervene in the Phase III adjudication. Relying in part on federal land patents that conveyed the land they now own to their predecessors, the Stutzmans claimed an individual, proportionate, state right to use water stored in Buffalo Bill Reservoir. Specifically, they claimed “implied” secondary rights by and through the reservoir permits, and ownership of a “pro-rata” or “proportionate” share of the stored reservoir water by virtue of, among other things, the federal land patents. In making this claim, they relied on the language contained in the patents’ haben-dum clause granting, in addition to the described tract, “the right to the use of water from the Shoshone Reclamation Project as an appurtenance to the irrigable lands in said tract.”
[¶ 6] The district court dismissed the Stutzmans’ claims as untimely and on March 10, 2004, we affirmed, holding, “[t]o the extent the Stutzmans sought to enforce their rights against the United States pursuant to the federal patents and contráete the district court lacked jurisdiction.
Big Horn,
[¶ 7] On May 14, 2004, the Stutzmans attempted to file several of the federal land patents as reservoir water deeds with the state engineer’s office. On June 2, 2004, the state engineer’s office returned the patents without filing them, stating “[t]he documents you provided are land patents and not deeds for reservoir water, therefore, the State Engineer’s Office cannot record them under WS 41-3-324.”
' [¶ 8]- The Stutzmans filed a petition for review in district court alleging that the state engineer unlawfully refused to file the land patents. The district court concluded the issue was governed by Big Horn, in which this Court “held that [the Stutzmans] do not have a personal state water right to appropriate water stored in the reservoir.” On that basis, the district court held the state engineer did not unlawfully withhold agency action and denied the Stutzmans’ petition. The Stutzmans appealed to this Court from the district court’s decision.
STANDARD OF REVIEW
[¶ 9] Pursuant to W.R.A.P. 12.09, our review o'f the issues is limited to a determination of the matters specified in Wyo. Stat. Ann. § 16 — 3—114(c) (LexisNexis 2005). Accordingly, we “decide all relevant questions of law, interpret constitutional and statutory provisions, and determine the meaning or applicability of the terms of an agency action.” Id. We review the whole record or those parts of it cited by the parties, taking into account the rule of prejudicial error. We shall:
(i) Compel agency action unlawfully withheld or unreasonably delayed; and
(ii) Hold unlawful and set aside agency action, findings and conclusions found to be:
*474 (A) Arbitrary, capricious, an abuse of discretion or otherwise not in accordance with law;
(B) Contrary to constitutional right, power, privilege or immunity;
(C) In excess of statutory jurisdiction, authority or limitations or lacking statutory right;
(D) Without observance of procedure required by law;
(E) Unsupported by substantial evidence in a case reviewed on the record of an agency hearing provided by statute.
Id.
We review an agency’s conclusions of law
de novo. Wyoming Dep’t of Trans. v. Haglund,
DISCUSSION
[¶ 10] The Stutzmans claim the district court incorrectly concluded our decision in Big Horn governed the issue of whether the state engineer’s office could properly file land patents under Wyo. Stat. Ann. § 41-3-324. They contend this Court ruled in Big Horn that the district court lacked jurisdiction over claims arising from federal patents; therefore, there was no ruling with regard to the federal patents and the issue is not res judi-cata. The state engineer contends the district court correctly ruled Big Horn controls the issue because that decision determined the Stutzmans did not have a legitimate claim to a state water right based upon the federal land patents. Therefore, the state engineer argues, the issue is res judicata.
[¶ 11] Our holding in Big Horn as it pertains to this appeal was two-fold. First, we held the district court lacked jurisdiction over the Stutzmans’ claim that they had the right to use water stored in the Buffalo Bill Reservoir to the extent they asserted it against the United States pursuant to federal patents and contracts. With respect to that aspect of their claim, we said the MeCarran Amendment gave only limited consent to the exercise of state court jurisdiction over the United States, consent which did not extend to claims against the federal government for enforcement of federal contracts. Second, we held that although the district court had jurisdiction to determine whether the Stutz-mans had a legitimate claim under state law to use water stored in the reservoir, it properly dismissed the claim because the Stutz-mans failed to timely assert it. We expressly limited our holding to the timeliness issue and did not address the merits of the Stutz-mans’ claim to an implied secondary right to use water stored in the reservoir.
[¶ 12] Neither of these holdings (that the district court lacked jurisdiction in the first instance and the Stutzmans’ claims were untimely in the second instance) directly addressed the issue now before us: in essence, whether the state engineer was required to file the federal patents as “deeds for reservoir water” pursuant to Wyo. Stat. Ann. § 41-3-324 and unlawfully withheld agency action by declining to do so. This is an issue of first impression in Wyoming. We begin our analysis by looking at the pertinent statutory language.
§ 41-3-324. Deeds and leases for water rights; execution and recording.
All deeds for reservoir water and water rights and all leases of the same for periods of three (3) years or more shall be executed and acknowledged as deeds are executed, and shall be recorded in the office of the county clerk of the county in which the reservoir is situated and also filed in the office of the state engineer.
[¶ 13] The Stutzmans argue the federal land patents are the legal equivalent of “deeds for reservoir water and water rights” because they conveyed the land together with “the right to use the water from the [reservoir] as an appurtenance to the irrigable lands.” The state engineer argues the land patents the Stutzmans submitted for filing do not qualify as valid deeds because they do not adequately describe the water *475 right conveyed. The state engineer also argues that because the Stutzmans failed to timely assert their alleged rights during Big Horn, they have no valid water right and requiring the state engineer to file the patents as if they did have a valid right would lead to absurd results.
[¶ 14] In interpreting and construing statutory language, our primary purpose is to determine the legislature’s intent.
Merrill v. Jansma,
[¶ 15] When the language is not clear or is ambiguous, we look to the mischief the statute was intended to cure, the historical setting surrounding its enactment, the public policy of the state, the conclusions of law, and other prior and contemporaneous facts and circumstances. These are the accepted rules of construction to ascertain a legislative intent that is reasonable and consistent. Id. A statute is ambiguous only if it is found to be vague or uncertain and subject to varying interpretations. Id. Ultimately, whether a statute is ambiguous is a matter of law to be determined by the court. Id.
[¶ 16] We will not insert language into a statute that the legislature omitted.
K.P. v. State,
[¶ 17] Wyo. Stat. Ann. § 41-3-324 clearly and unambiguously provides that all deeds for reservoir water and water rights
shall
be filed in the office of the state engineer. Where the legislature uses the word “shall,” this Court accepts the provision as mandatory and has no right to make the law contrary to what the legislature prescribed.
Merrill,
[¶ 18] The phrase “deeds for reservoir water and water rights” is not expressly defined in the Wyoming Statutes. However, giving the words their plain and ordinary meaning, federal land patents conveying land together with “the right to use the water from the [reservoir] as an appurtenance to the irrigable lands,” would seem to fall within the meaning of the phrase. A deed is “a written instrument, signed and delivered, by which one person conveys land, tenements, or hereditaments to another.” Black’s Law Dictionary 414 (6th ed.). The federal land patents are written instruments by which the federal government conveyed land to the Stutzmans’ predecessors in interest together with the right to use water from the reservoir. We hold they fall within the meaning of Wyo. Stat. Ann. § 41-3-324 and are, therefore, subject to the filing requirement.
[¶ 19] The state engineer argues, however, this is not a correct result because it would require his office to treat the patents as though they conveyed valid rights to reservoir water when in fact they do not under Wyoming law because the Stutzmans failed to timely assert their claim during the Big Horn River Adjudication. The state engineer asserts a determination by this Court that Wyo. Stat. Ann. § 41-3-324 required these patents to be filed in his office would lead to an absurd result, an outcome this Court has expressly rejected in cases requiring a determination of legislative intent. We agree. Given our holding in Big Horn that the Stutzmans were time barred from asserting any claim to state water rights they may have had under the federal land patents, it would be absurd for this Court to require the state engineer to file the patents.
*476
[¶ 20] In two prior cases, this Court considered the purpose of the filing requirement contained in Wyo. Stat. Ann. § 41-3-324. In
Sturgeon v. Brooks,
[¶ 21] Affirmed.
