Exhibit 99.1 CAWLEY, GILLESPIE & ASSOCIATES, INC. PETROLEUM CONSULTANTS  13640 BRIARWICK DRIVE, SUITE 100 AUSTIN, TEXAS
78729-1707 512-249-7000

306 WEST SEVENTH STREET, SUITE 302
FORT WORTH, TEXAS 76102-4987 817- 336-2461 www.cgaus.com

1000 LOUISIANA STREET, SUITE 1900 HOUSTON, TEXAS 77002-5008
713-651-9944 February 22, 2023 Mr. Ron
Hooper Permian Basin Royalty Trust 2911 Turtle Creek Blvd., Suite 850 Dallas, Texas 75219  Re:   Evaluation Summary
Permian Basin Royalty Trust Interests
Proved Reserves As of December 31,
2022

Pursuant to the Rules and Regulations of the
Securities and Exchange Commission for Reporting Corporate Reserves
and Future Net Revenue Dear Mr. Hooper: As requested, we are submitting this report of the estimates of proved reserves and economics forecasts attributable to the Permian Basin Royalty Trust
interests effective as of December 31, 2022, completed February 22, 2023 for the purpose of reporting corporate reserves and future net revenue. This report has been prepared for the Permian Basin Royalty Trust pursuant to the rules,
regulations and guidelines of the Securities and Exchange Commission, Item 1202 (a) (8) of Regulation S-K, for reporting corporate reserves and future net revenue. We reviewed 100 percent of the
total proved reserves of the Permian Basin Royalty Trust in connection with the preparation of this report. The proved reserves presented in this report constitute 100 percent of the proved reserves owned by the Permian Basin Royalty Trust, all
of which are located in the United States. Composite reserve estimates and economic forecasts for the proved reserves are summarized below:  Texas RoyaltyProperties


WaddellRanch PropertiesTotal Proved


ProvedDevelopedProducing


ProvedDevelopedProducing


ProvedDevelopedNon-Producing


ProvedUndevelopedNet ReservesOil/Condensate


- Mbbl



11,552.8



2,659.7



5,179.5



182.8



3,530.9Gas


- MMcf



25,737.1



1,320.5



19,210.1



685.0



4,521.4Net RevenueOil/Condensate


- M$



1,071,712.8



245,274.2



481,329.8



16,984.5



328,124.3Gas


- M$



196,806.6



15,117.7



142,946.6



5,097.6



33,644.7Severance Taxes


- M$



63,291.7



10,358.9



33,877.0



1,199.8



17,856.0Operating Income (BFIT)


- M$



1,205,228.0



250,033.1



590,399.3



20,882.3



343,913.0Discounted at 10%


- M$



686,466.6



107,013.3



378,214.6



10,651.8



190,586.9 In accordance with the Securities and Exchange Commission guidelines, the future net cash flow, operating income (BFIT), has been
discounted at an annual rate of 10% to determine its present worth. The discounted value, present worth, is indicative of the time value of money. The discounted value, present worth, shown above should not be
construed to represent an estimate of the fair market value by Cawley, Gillespie & Associates, Inc.




---

Mr. Ron Hooper Permian Basin
Royalty Trust Interests February 22, 2023 Page 2  The Permian Basin Royalty Trust consists of the Waddell Ranch Properties located
in Crane County, Texas, and the Texas Royalty Properties located in various counties in Texas. As to the assumptions, methods and procedures used
in connection with the preparation of this report, prices were forecast in accordance with Securities and Exchange Commission rules and guidelines. The prices are determined as an unweighted arithmetic average of the
first-day-of-the-month benchmark price for each month of 2022. The 12-month average benchmark Henry Hub spot gas price of $6.36 per MMBtu and 12-month average benchmark WTI Cushing spot oil price of $93.67 per barrel were used. The oil and
gas prices were held constant throughout the life of the properties. The prices were adjusted for gravity, quality, heating value, transportation and marketing. For the Texas Royalty Properties, the gas and oil prices were adjusted using
differentials of +$5.09 per Mcf and -$1.45 per barrel, respectively. For the Waddell Ranch Properties, the gas and oil prices were adjusted using differentials of +$1.08 per Mcf and -$0.74 per barrel, respectively. Deductions were applied to the net
gas volumes for fuel and shrinkage. For the Texas Royalty Properties, the adjusted volume-weighted average product prices over the life of the properties are $92.22 per barrel and $11.45 per MCF, respectively. For the Waddell Ranch Properties, the
adjusted volume-weighted average product prices over the life of the properties are $92.93 per barrel and $7.44 per MCF, respectively. For the
Waddell Ranch Properties, operating expenses and capital costs were based on an analysis of data provided by Blackbeard Operating. Operating expenses include direct lease operating expenses and administrative overhead and were forecast as $4,900 per
well per month and $8.25 per barrel of oil. Investments include drilling costs, work-over costs, production equipment and facilities costs. No operating expense or capital cost data is available for the Texas Royalty Properties since they are purely
a royalty interest only. Based on an analysis of the Permian Basin Royalty Trust Monthly reports, severance taxes were forecast as 4.60% and 8.21% of oil and gas revenue, respectively, for the Waddell Ranch Properties. For the Texas Royalty
Properties, severance taxes were forecast as 3.84% and 6.22% of oil and gas revenue, respectively. The ad valorem taxes were forecast as 0.39% and 3.64% for the Waddell Ranch Properties and the Texas Royalty Properties, respectively. Neither
expenses nor investments were escalated. The cost of plugging and the salvage value of equipment have not been considered. The reserves were
estimated using the production performance, volumetric or analogy methods, or a combination of these methods. In each case, we used the method or combination of methods that we considered appropriate and necessary to establish the reserves and
conclusions presented. Riverhill Energy Corporation supplied the royalty production data for the Texas Royalty Properties. For these properties, the proved producing reserves are forecast using the production performance, decline analysis method to
an estimated final production rate equal to approximately one-tenth of the current production rate. The producing reserves for the Waddell Ranch Properties were estimated using the production performance or
analogy methods or a combination of these methods. The non-producing reserves were estimated using the analogy or volumetric methods or a combination of these methods. The reserve classifications conform to the definitions and criteria of the Securities and Exchange Commission. The reserves and economics are predicated
on the regulatory agency classifications, rules, policies, laws, taxes and royalties in effect on the effective date except as noted herein. The possible effects of changes in legislation or other Federal or State restrictive actions which could
affect the reserves and economics have not been considered. We are not aware of any legislative changes or restrictive actions that may possibly impact the reserves or economics as presented. Possible environmental liability related to the
properties has not been investigated nor considered. The assumptions, data, methods and procedures as described are appropriate for the purpose of this report. All reserve estimates represent our best judgment based on data available at the time of
preparation and assumptions as to future economic and regulatory conditions. Due to the inherent uncertainties of reserves estimates, future production rates, commodity prices, costs and expenses, it should be realized that the reserves actually
recovered, the revenue received and the actual cost incurred could be more or less than the estimated amounts.




---

Mr. Ron Hooper Permian Basin
Royalty Trust Interests February 22, 2023 Page 3  The reserve estimates were based on interpretations of factual data furnished by
Blackbeard Operating, Riverhill Energy Corporation and the Permian Basin Royalty Trust. Liquid and gas price information, cost and expense history, subject wells and ownership were supplied by one or more of the above and were accepted as furnished.
To some extent, information from public records has been used to check and/or supplement these data. The basic engineering and geological data were utilized subject to third party reservations and qualifications. Nothing has come to our attention,
however, that would cause us to believe that we are not justified in relying on such data. An on-site inspection of these properties has not been made nor have the wells been tested by Cawley,
Gillespie & Associates, Inc. We have used all methods and procedures that we consider necessary under the circumstances to prepare this report. Cawley, Gillespie & Associates, Inc. is independent with respect to the Permian Basin Royalty Trust as provided in the Standards Pertaining to
the Estimating and Auditing of Oil and Gas Reserve Information promulgated by the Society of Petroleum Engineers. Neither Cawley, Gillespie & Associates, Inc. nor any of its employees has any interest in the subject properties. Neither the
employment to make this study nor the compensation is contingent on the results of our work or the future performance of the subject properties. Cawley, Gillespie and Associates, Inc. is a Texas registered engineering firm, F-693, of professional engineers and geologists serving the oil and gas industry for over fifty years. This report was prepared by, or under the supervision of, J. Zane Meekins, a Texas registered professional
engineer (License No. 71055).  Respectfully submitted,LOGOCAWLEY, GILLESPIE & ASSOCIATES, INC.Texas Registered Engineering Firm F-693LOGOJ. Zane Meekins, P.E.Executive Vice President