Exhibit 99.1

CALHOUN, BLAIR & ASSOCIATES

PETROLEUM CONSULTANTS

4625 GREENVILLE AVENUE, SUITE 102

DALLAS, TEXAS 75206

(214)-522-4925

FACSIMILE: (214) 346-0310

RGBLAIR@SWBELL.NET

February 16, 2010

Dorchester Minerals Operating GP LLC

General Partner

3838 Oak Lawn Avenue, Suite 300

Dallas, Texas
75219-4541

Gentlemen:

In accordance with your instructions we have prepared estimates of oil and gas reserves from certain leasehold and royalty interests owned by Dorchester Minerals Operating LP, which consists of properties grouped by Hugoton NPI, Republic
NPI, Spinnaker NPI, Minerals NPI and Bradley NPI. We have projected our estimates of future oil and gas production annually, as of January 1, 2010, for these properties. This report includes 100% of the oil and gas reserves owned by Dorchester
Minerals Operating, LP, all of which are located in the contiguous United States.

Information necessary for the preparation
of these estimates was obtained from records furnished by Dorchester Minerals Operating LP, from records on file with the state regulatory bodies, and from our own files.No special tests were obtained to assist in the preparation of this
report. For the purpose of this report, the individual well tests and production information as reported in the records on file with the state regulatory bodies were accepted as represented, together with all other factual data provided by
Dorchester Minerals Operating LP, including the extent and character of the interest appraised.

The following table contains
the estimated net reserves and revenues attributable to the property groups that are currently in pay status as of January 1, 2010.



|                            |  |            |  |             |  |             |  |           
|--------------------------- |  | ---------- |  | ----------- |  | ----------- |  | ----------
|                            |  | HugotonNPI |  | RepublicNPI |  | SpinakerNPI |  | Total     
|Net Oil Reserves, BBL       |  | 0          |  | 40,490      |  | 320         |  | 40,810    
|Net Gas Reserves, MMCF      |  | 25,634.760 |  | 471.700     |  | 42.990      |  | 26,149.450
|Net Oil and Gas Revenue, $  |  | 76,987,010 |  | 3,744,530   |  | 197,900     |  | 80,929,440
|Net Operating Expense, $    |  | 39,752,220 |  | 1,140,760   |  | 68,460      |  | 40,961,440
|Net Taxes, $                |  | 6,557,170  |  | 370,340     |  | 15,140      |  | 6,942,650 
|Net Capital Costs, $        |  | 470,000    |  | 0           |  | 0           |  | 470,000   
|Net Income, $               |  | 30,207,620 |  | 2,233,430   |  | 114,310     |  | 32,555,360
|Net Present Worth at 10%, $ |  | 21,747,930 |  | 1,640,890   |  | 86,820      |  | 23,475,640



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CALHOUN, BLAIR & ASSOCIATES



The estimated net reserves and revenues for the property groups that are in a deficit
pay status as of January 1, 2010 are as follows:



|                               |  |             |  |            |  |           
|------------------------------ |  | ----------- |  | ---------- |  | ----------
|                               |  | MineralsNPI |  | BradleyNPI |  | Total     
|Net Oil Reserves, BBL          |  | 65,330      |  | 170        |  | 65,500    
|Net Gas Reserves, MMCF         |  | 3,016.100   |  | 0.430      |  | 3,016.530 
|Net Oil and Gas Revenue, $     |  | 13,586,620  |  | 11,370     |  | 13,597,990
|Net Lease Operating Expense, $ |  | 3,709,670   |  | 2,390      |  | 3,712,060 
|Net Taxes, $                   |  | 927,200     |  | 850        |  | 928,050   
|Net Capital Costs, $           |  | 0           |  | 0          |  | 0         
|Net Income, $                  |  | 8,949,750   |  | 8,130      |  | 8,957,880 
|Net Present Worth at 10%, $    |  | 6,450,630   |  | 7,150      |  | 6,457,780 

All estimated
reserves in this report are considered as proved developed producing. Proved developed producing reserves are those proved to a high degree of certainty by reason of actual completion or successful testing. Estimates of proved reserves were made
using standard geological and engineering methods accepted by the petroleum industry. The method, or combination of methods, utilized was tempered by experience in the area, state of development, quality and extent of the basic data and production
history. These methods and procedures were appropriate for the purpose served by this report and we have used all methods necessary under the circumstances to prepare this report.

When the information was available and the method was applicable, oil and gas reserves in this report were estimated by the extrapolation of
historical trends of pressure decline as a function of cumulative production, oil and gas production decline as a function of time and oil and gas production decline as a function of cumulative production. For certain wells having a limited
production history, reserves were estimated by analogy with nearby similar wells in the same formation. All gas volumes are raw wellhead gas volumes expressed at 60 degrees Fahrenheit and at a standard pressure base of 14.65 pounds per square inch
absolute.

Reserves in this report are expressed as gross and net oil and gas production. Net oil and gas production
represents those reserves net to the appraised interest after deducting all leasehold and royalty interests owned by others. Values of reserves are expressed in terms of net operating revenues, cash flow before taxes, and present worth. Net
operating revenue is revenue, which would accrue to the appraised interests from the production and sale of the estimated net reserves. Cash flow before taxes is obtained by deducting severance and ad valorem taxes, net operating expenses and
capital costs from net operating revenue. Net operating expenses include an allocation of supervisory costs chargeable to the leases but do not include general and administrative overhead. Oil and gas prices, net operating expenses and future
capital costs were furnished by Dorchester Minerals Operating LP. Present worth is defined as the future cash flow before taxes discounted at the rate of ten (10.00) percent per year compounded annually. For the purpose of this report no
estimate was made of salvage value for the existing lease and well equipment, or costs involved in abandonment of the wells.

Due to inherent uncertainties in future production rates, commodity prices and geologic conditions, the reserves included in this report are estimates only and should not be construed as being exact quantities. The revenues from such
reserves and the actual costs related thereto could be



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CALHOUN, BLAIR & ASSOCIATES



more or less than the estimated amounts. The scope of this investigation did not include an
environmental study of these properties, nor was an on-site field inspection conducted. For the purpose of this report, it was necessary to assume that these properties are in compliance with existing government regulations. Because of governmental
policies and uncertainties of supply and demand, the prices actually received for the reserves included in this report, and the costs incurred in recovering such reserves, may vary from price and cost assumptions in this report. In any case,
estimates of reserves may increase or decrease as a result of future operation and as more production history becomes available. There are no known pending regulations that would affect the ability of Dorchester Minerals Operating LP to recover the
estimated reserves in this report.

The oil and gas prices included in this report were provided by Dorchester Minerals
Operating LP and were adjusted for BTU, fuel and line losses as well as for local markets. The prices used were determined as an unweighted arithmetic average of the first day of the month price during the twelve month period of 2009. The base gas
price for the Oklahoma Hugoton operated properties was $3.03 per MMBTU while the Kansas price was $2.81 per MMBTU. The average oil and gas prices for the other NPI properties were $61.04 per barrel and $3.78 per MMBTU, respectively.

Calhoun, Blair & Associates have not examined the title to these properties, nor has the actual degree or type of interest owned
been independently confirmed. We are independent petroleum engineers; we do not own an interest in these properties and are not employed on a contingent basis. Basic field performance data together with our engineering work sheets are maintained on
file in our office and are available for review.

Included in this report are summaries of gross and net oil and gas reserves
grouped by Hugoton NPI, Republic NPI, Spinnaker NPI, Minerals NPI and Bradley NPI. Also included are projections of estimated annual gross and net oil and gas production, net operating revenue, severance and ad valorem taxes, net operating expenses,
net capital costs, cash flow before taxes, and present worth for all properties appraised as of January 1, 2010. Present worth of future cash flow is not meant to represent the Fair Market Value of these properties or of Dorchester Minerals
Operating LP.



Yours very truly,/s/ Robert G. Blair, P.E.Calhoun, Blair & AssociatesLicensed Professional EngineerState of Texas #68057