RULE 138.00.16-002 - Arkansas-Oklahoma Arkansas River Compact Commission Rules, Regulations, and Modes of Procedure

RULE 138.00.16-002. Arkansas-Oklahoma Arkansas River Compact Commission Rules, Regulations, and Modes of Procedure


(As Amended September 25, 1985, September 25, 1991, September 24, 1993, September 27, 2012, and September 24, 2015)



1.1 The "Commission" is the "Arkansas-Oklahoma Arkansas River Compact Commission" referred to in Article VIII of the Arkansas River Basin Compact, Arkansas-Oklahoma.

1.2 The credentials of each Commissioner shall be filed with both the Chairman and the Secretary of the Commission. When the credentials of a new Commissioner are received, the Secretary shall promptly notify all other Commissioners of the name and address of the new Commissioner.

1.3 Each Commissioner shall advise the Commission in writing of the address to which all official notices and other Commission communications shall be sent for their receipt and shall further promptly advise in writing the office of the Commission of any changes in address.



2.1 The officers of the Commission shall be a Chairman, a Secretary and a Treasurer.

2.2 The Commissioner (or "alternate") representing the United States shall be the Chairman of the Commission. The Chairman shall preside at meetings of the Commission. His duties shall be those usually imposed upon such officers and as may be assigned by these rules or by the Commission from time to time.

2.3 The Secretary shall be selected by the Commission. The Secretary shall serve for the term, and shall perform the duties, as the Commission shall direct. In case of a vacancy in the office of the Secretary, the Commission shall select a new Secretary as expeditiously as possible.

2.4 The Treasurer shall be selected by the Commission. The Treasurer shall receive, hold and disperse all funds of the Commission which shall come into his hands, and shall furnish a fidelity bond in an amount satisfactory to the Commission. The cost of the bond shall be paid by the Commission.

2.5 As the Commission may determine and direct, the various Commission officer positions may be joined and simultaneously held by the same person.


3.1 The principal office of the Commission shall be the office of the Chairman or the Secretary, as the Commission shall direct.

3.2 All official files, books and records of the Commission shall be kept and maintained in the principal office of the Commission. All such files, books and records shall be open to inspection by the public at the principal office of the Commission.


4.1 The annual meeting of the Commission shall be held on the fourth Thursday in September of each year. By prior agreement of all Commissioners, the Commission may select and designate a different date for holding the annual meeting.

4.2 Special meetings of the Commission may be called by the Chairman at any time. Upon written request of a majority of the Commissioners of either of the signatory states setting forth the matters to be considered at a special meeting, it shall be the duty of the Chairman to call a special meeting. Notice of all special meetings shall be sent by the Secretary to all members of the Commission by ordinary mail at least ten days in advance of the meeting and such notice shall state the purpose thereof.

4.3 Emergency meetings of the Commission may be called by the Chairman at any time upon request of either signatory state. For purposes of this rule, an "emergency" situation, for which an emergency meeting may be called, is understood to mean a situation involving an imminent threat of injury to persons or injury and damage to public or personal property or threat of imminent financial loss when time requirements make prior notice procedures impractical and, if adhered to, would increase the likelihood of injury, damage or financial loss.

4.4 Except as otherwise provided herein, prior notice of all Commission meetings shall be given by the Secretary to all Commissioners. Such notice shall advise of the date, time and place of the meeting and shall include an agenda for the meeting or, as may be applicable, a statement of the purpose of or matters to be considered at the meeting. Upon receipt of such notice, it shall be the responsibility of the signatory state to, in-turn, furnish notice to the public in its state such as may be required or provided under the laws of that state. Except as may be otherwise required under the laws of a signatory state, no advance public notice shall be required for the calling and conducting of emergency meetings. At the earliest possible time following any emergency meeting, the public will be notified of any Commission action taken at the meeting.

4.5 Meetings of the Commission shall be held at such places as shall be agreed upon by the Commissioners.

4.6 Minutes of Commission meetings shall be made and preserved in a suitable manner. Until approved by the Commission, minutes shall not be official and shall be furnished only to members of the Commission, its employees and committees.

4.7 A majority of the Commissioners of each state, and the Commissioner (or alternate) representing the United States, must be present to constitute a quorum.

4.8 In taking any Commission action, each signatory state shall have a single vote representing the majority opinion of the Commissioners of that State. The Commissioner (or alternate) representing the United States shall not have the right to vote in any of the deliberations or actions of the Commission.

4.9 In the case of a tie vote on any of the Commission's determinations, orders, or other actions, a majority of the Commissioners of either state may, upon written request to the Chairman, submit the question to arbitration. Arbitration shall not be compulsory, but, in the event of arbitration, there shall be three arbitrators chosen as follows:

(1) One named by resolution duly adopted by the Arkansas Soil and Water Conservation Commission, or such other State agency as may be hereafter responsible for administering water law in the State of Arkansas; and

(2) One named by resolution duly adopted by the Oklahoma Water Resources Board, or such other State agency as may be hereafter responsible for administering water law in the State of Oklahoma; and

(3) The third chosen by the two arbitrators who are selected as provided above.

If the two arbitrators fail to select a third within sixty (60) days following their selection, then the third arbitrator shall be chosen by the Chairman of the Commission.

4.10 At each annual meeting of the Commission, the order of business, unless agreed otherwise, shall be as follows:

1. Call to Order;

2. Introductions and Announcements;

3. Approval of Agenda;

4. Reading, Correction and Approval of the Last Meeting;

5. Report of the Chairman;

6. Report of Secretary;

7. Report of Treasurer;

8. Report of Commissioners;

9. Report of Committees;

10. Unfinished Business;

11. New Business; and

12. Adjournment.

4.11 All meetings of the Commission, except executive sessions, shall be open to the public. Executive sessions shall be open only to members of the Commission and such advisers as may be designated by each member and employees as permitted by the Commission; provided, however, that the Commission may call witnesses before it when in executive session. The Commission may hold executive sessions only for the purposes of discussing:

(1) The employment, appointment, promotion, demotion, disciplining or resignation of a Commission employee or employees, members, advisers, or committee members;

(2) Pending or contemplated litigation or litigation settlement offers, and matters where the duty of the Commission's counsel to its client, pursuant to the Code of Professional Responsibility, clearly conflicts with the public's right to know; or

(3) The report, development, or course of action regarding security, personnel, plans, or devices.

No executive session may be held except on a vote, taken in public, by a majority of a quorum of the members present. Any motion or other decision considered or arrived at in executive session shall be voidable unless, following the executive session, the Commission reconvenes in public session and presents and votes on such motion or other decision.



5.1 There shall be the following standing committees:

(a) Budget Committee;

(b) Engineering Committee;

(c) Environmental and Natural Resources Committee; and

(d) Legal Committee.

5.2 The Committees shall have the following duties:

(a) The Budget Committee shall prepare the annual budget and advise the Commission on all fiscal matters that may be referred to it.

(b) The Engineering Committee shall advise the Commission on all engineering matters that may be referred to it.

(c) The Environmental and Natural Resources Committee shall advise the Commission on all environmental and natural resource matters including:

(1) the identification of common areas of environmental concerns and potential solutions to shared environmental and natural resource problems;

(2) the promotion of environmental awareness and sustainable economic development; and

(3) other environmental and natural resource matters that may be referred to it.

(d) The Legal Committee shall advise the Commission on all legal matters that may be referred to it.

5.3 Members of the standing committees shall be appointed by the Commission. The number of members of each committee shall be determined by the Commission. Each state shall be represented by an equal number of members on each committee with the Chairmanship for each committee alternating annually between the States of Arkansas and Oklahoma. Each state shall nominate the member or members representing the state to serve on each committee.

5.4 Formal committee reports shall be made in writing by the Chairman thereof, and shall be filed with the Commission at least ten days prior to the meeting scheduled for its discussion.


6.1 So far as is consistent with the Arkansas-Oklahoma Arkansas River Basin Compact, the Commission may adopt rules and regulations and may amend them from time to time. Amendments and/or revisions to the rules, regulations and modes of procedure may be made at any meeting of the Commission.

6.2 Rules and regulations of the Commission may be compiled and copies may be prepared for distribution to the public under such terms and conditions as the Commission may prescribe.


7.1 All Commission funds shall be deposited in a depository, or depositories, designated by the Commission under the name of the "Arkansas-Oklahoma Arkansas River Compact Fund." Such funds shall be initiated and maintained by equal payments of each state into the fund.

** 7.2 Disbursements of funds in the hands of the Treasurer shall be made by check signed by the Treasurer and another authorized signatory upon voucher approved by and reported to the Commission. All Commissioners are authorized signatories.

7.3 At each annual meeting of the Commission, the Commission shall adopt and transmit to the Governors of the two states the budget covering an estimate of its expenses for the following fiscal year. For purposes of this rule and requirement, the signatory states may individually assume and carry-out the responsibility of transmitting the Commission's adopted budget to that state's respective Governor.

7.4 All Commission receipts and disbursements shall be audited at least once every two years by a qualified independent certified public accountant to be selected by the Commission, and the report of the audit shall be included in, and become a part of, the annual report of the Commission.

7.5 An up-to-date inventory of all Commission property shall be kept at the principal office of the Commission.

7.6 The fiscal year of the Commission shall begin July 1 of each year and end June 30 of the next succeeding year.



8.1 The Commission shall annually make and transmit as soon as available to the Governors of the signatory states, and to the President of the United States, a report covering the activities of the Commission for the preceding fiscal year.

8.2 The annual report shall include the following:

(a) Minutes of all regular, special or emergency meetings held during the year;

(b) All findings of facts made by the Commission during the preceding year;

(c) Recommendations for actions by the signatory states;

(d) Statements as to any cooperative studies made during the preceding year;

(e) All data which the Commission deems pertinent;

(f) The budget for current and future years;

(g) The most recent audit or financial statement of the Arkansas-Oklahoma Arkansas River Compact Fund;

(h) Name, address and phone number of each Commissioner and each member of all standing committees; and

(i) Such other pertinent matters as the Commission may require.


9.1 The Commission shall on request make available to the Governor of each of the signatory states any information within its possession at any time.

9.2 All contracts or other instruments in writing to be signed for and on behalf of the Commission, except matters related to the receipt or disbursement of funds, shall be signed by the Chairman when authorized by the Commission and attested to by at least one Commissioner from each State.

9.3 The Commission shall have the power to employ such engineering, legal, clerical and other personnel as in its judgment may be necessary for the performance of its functions under the Compact.


*10.1(A) As the Commission may determine and direct, the Commission may hold hearings for the purpose of taking testimony and receiving evidence for the identification of interstate problems within the purposes of this Compact and issuing such appropriate orders as it deems necessary for the proper administration of the Arkansas-Oklahoma Arkansas River Basin Compact. Any interested person or entity may make application to the Commission requesting that a hearing be held on any matter arising under, or otherwise within the purview of, the Compact, provided, such applications must meet the following requirements:

(a) The application must be in writing and filed with the Chairman, with a copy thereof being simultaneously furnished, by the applicant, to all Commissioners.

(b) The application must state and describe the identity and address of the applicant(s) and, where appropriate, the applicant's representatives in pursuit of the application; the interest of the applicant(s) in presenting the application and requesting that a hearing be held; the purpose, subject matter, issues, concerns and/or allegations sought to be entertained and considered through the hearing applied for; and, as may be appropriate to the purposes of the hearing sought, the relief or other official Commission action being requested through the hearing.

Unless determined and directed otherwise by the Commission, applications for Commission hearings shall be placed, for Commission review and consideration, on the agenda for the next regularly scheduled annual meeting of the Commission following the filing of the application. Applicant(s) shall be notified, in advance by the Chairman, of the date, time and place of the meeting at which the application will be considered and acted upon by the Commission.

10.1(B) All hearings shall be open to the public and may be scheduled and conducted as part of an annual or special meeting of the Commission or as may be determined otherwise by the Commission. The presiding officers at such hearings shall be one Commissioner from each state designated and appointed to serve as presiding officer by the respective state.

10.2 Orders of the Commission shall be enforceable upon the request of the Commission or any other interested party in any court of competent jurisdiction within the county wherein the subject matter to which the order relates is in existence, subject to the right of review through the appellate courts of the state of situs.

10.3 Any hearing held for the promulgation and issuance of orders shall be in the county and state of the subject matter of said hearing.

10.4 In the event the Commission directs that a hearing be held, all interested parties shall be afforded an opportunity to be heard after reasonable notice. Such notice shall include, among other matters deemed appropriate:

(a) A statement of the date, time, place, and nature of the hearing;

(b) A statement of the legal authority and jurisdiction under which the hearing is to be held;

(c) A reference to any particular matter or any statute or rules involved; and

(d) A short and plain statement of the matters asserted or which are the subject or purpose of the hearing.

If the Commission, or any other interested party, is unable to state the matters in detail at the time the notice is served, the initial notice may be limited to a statement of the issues. Thereafter, and upon application, a more definite and detailed statement shall be furnished.

10.5 A record of the hearing shall be kept and maintained and shall include:

(a) All pleadings, motions and intermediate rulings;

(b) Evidence received or considered;

(c) A statement of matters officially noticed;

(d) Questions and offers of proof, objections, and rulings thereon;

(e) Proposed findings and exceptions thereto;

(f) Any decision, opinion or report by the officers presiding at the hearing; and

(g) All staff memoranda or data submitted to the Commission in connection with their consideration of the matter before such hearing.

10.6 Findings of facts shall be based exclusively on the evidence and on the matters officially noticed by the Commission.

10.7 Oral proceedings or any part thereof shall be transcribed on request of any party and the cost of transcription shall be paid by the requesting party.

10.8 At its hearings, the Commission may admit and give probative effect to evidence which possesses probative value commonly accepted by reasonably prudent men in the conduct of their affairs. It shall give effect to the rules of privileged communications recognized by law. No greater exclusionary effect shall be given any such rule or privilege than would be obtained in an action in court. The Commission may exclude incompetent, irrelevant, immaterial and unduly repetitious evidence. Objections to evidentiary offers may be made and shall be noted in the record. Subject to these requirements, when a hearing will be expedited and the interest of the parties will not be prejudiced substantially thereby, any part of the evidence may be received in written form.

*10.9 Documentary evidence may be received in the form of copies or excerpts if the original is not readily available. Upon request, the parties shall be given an opportunity to compare the copy with the original. The record of hearings may be held open for a reasonable length of time to afford either party time to submit additional written statements or evidence. An original and two copies (or three copies) of each document sought to be introduced into evidence by a party at a Commission hearing must be presented to the officers presiding over the hearing by the party desiring and moving its admission.

10.10 A party may conduct cross-examination required for a full and true disclosure of the facts.

10.11 Notice may be taken of judicially recognized facts. In addition, notice may be taken of generally recognized technical or scientific facts within the Commission's specialized knowledge. Parties shall be notified, either before or during the hearing or be referenced in preliminary reports or otherwise, of the material noticed, including any staff memoranda or data, and they shall be afforded an opportunity to contest the material so noticed. The Commission's experience, technical competence and specialized knowledge may be utilized in the evaluation of the evidence.

10.12 In the case of hearings involving alleged or apparent violations of the Compact, the following procedures shall apply:

(a) If there is an alleged or apparent violation of the Compact, it should be made known to the Commission;

(b) Alleged violators shall submit an explanation for, or response to, the alleged violation to the Commission within thirty days of receipt of written notification of said violation from the Commission;

(c) The Commission shall refer the alleged violation to the Engineering and/or Legal Committee for investigation and review;

(d) After due investigation has been made, the Engineering and/or Legal Committee shall refer the matter to the Commission with recommendations concerning the action to be taken.

10.13 Any party shall at all times have the right to counsel, provided that such counsel must be duly licensed to practice law in one of the signatory States, or associated with an attorney thereof.



11.1 Prior to the close of each meeting, the Chairman may draft a press release as directed by the Commission and submit it to the Commission for approval. All approved releases may be made available to the press by any member of the Commission.

11.2 The Commissioners shall not be restricted from participation in a press conference or interview, conducted at the request of a member of the press or other news media, but may not speak on behalf of the Commission without the prior approval of the Commission.



12.1 The Commission may provide a forum for the identification and discussion of pollution occurring in the Arkansas River Basin to the end that the signatory states will cooperate with each other and jointly encourage the maintenance of an active pollution abatement program in each of the two states.

12.2 The Commission shall encourage each individual state to take positive steps in the abatement of pollution identified by the Commission to exist in the Arkansas River Basin; provided however, neither state may require the other to provide water for the purpose of water quality control as a substitute for adequate waste treatment.

12.3 The Commission shall collect, analyze and report on data pertaining to water quality within the basin. For this purpose the Commission may enter into contracts as provided by Article IX, A(2) to be approved at a Commission meeting. Unless formally approved by the Commission, no such report shall be published or have any validity.


13.1 The Arkansas Natural Resources Commission and the Oklahoma Water Resources Board representatives of the Engineering Committee will calculate the annual yield using the following data:

(a) Stream flows (USGS);

(b) Precipitation on reservoir surface (USACE);

(c) Evaporation from reservoir surface (USACE);

(d) Diversions from streams (OWRB and ANRC);

(e) Diversions from reservoir (USACE); and

(f) Return flows (State's DEQ).

13.2 The most recent data available will be used for all calculations. Each state agency shall have free access to the other state agency's data. The states should review, investigate, and possibly include historical data and averages if current year reported data is significantly different from previous years. If there is disagreement regarding the data used in the calculations, the agencies may schedule a conference call for clarification and resolution of the disagreement.

13.3 . Current computation methods used to calculate the annual yield have been agreed to by both state agencies and are attached to these rules as A-1.

13.4 Any state proposing a change to the "Guidelines for the Computation of Annual Yields" for calculating the annual yield for a certain water year must bring the proposed change to the engineering committee for review. If the changes are deemed important enough to be included in the current year's report, the engineering committee members shall hold a conference call to discuss the topic. Prior to adopting the method for usage in the yield report, the engineering committee must agree upon a defined process for using the changed methodology to consistently obtain and calculate data.

13.5 Any grievances regarding the calculation of the annual yield should be presented to the Commission with supporting evidence.

*As amended at the annual meeting, September 25, 1985.

**As amended at the annual meeting, September 25, 1991.

***As amended at the annual meeting, September 24, 1993.

****As amended at the annual meeting, September 27, 2012.

*****As amended at the annual meeting, September 24, 2015.


Guidelines for the Computation of Annual Yields

September 24, 2015

This document describes methods developed and approved by the Arkansas River Basin Compact Commission to compute the annual yields for the Spavinaw Creek, Illinois River, Lee Creek, Poteau River and Arkansas River Sub-basins of the Oklahoma-Arkansas River Compact.

General Description of Computation of Annual Yields

To compute annual yields for the Sub-basins identified above, one must take the following steps:

1. Determine the computation of actual runoff from each Sub-basin.

2. Determine the computation of total depletions or accretions in each of the respective Sub-basins.

3. Combine items (1) and (2) to obtain the "annual yield" for each basin.

4. Multiply item (3) by 100 minus the percentage of depletion allowed in Article IV of the Compact.

5. Compute deficiency, if any, by comparing item (4) to (1).

Items 1 and 2 are explained in this document, as these involve interpretation of the Compact, data collection and application of appropriate methods for computation of runoff, accretions, and depletions. Items 3 to 5 are not included herein as these are self-explanatory.

1. Computation of Actual Runoff from each Sub-basin

*The Engineering Committee will compute runoff data_from the Sub-basins using the areas defined by the Compact in Article II. Active USGS streamflow gauges should be used to retrieve measured runoff as available. Since most gauges are not located on the Oklahoma-Arkansas state border, estimates of runoff should account for the ungauged flows generated in the drainage area above or below the selected gauge.

The Engineering Committee will adjust the runoff measured at the gauges for the Spavinaw Creek, Illinois River, Lee Creek,and Poteau River Sub-basins-using simple linear interpolation, as follows:


R= Actual runoff at the OK-ARK state line

Rm= Measured runoff at the gauge

AG= Contributing area at the gauge

AU= Area ungauged above or below gauge

At= Total area including ungauged portion. Because water from these Sub-basins originates

in the state of Arkansas, then:

*If gauge is located on the Oklahoma side: At = AG - Au

*If gauge is located on Arkansas side: AT = AG + AU

The annual yields report should include a brief description of the procedure used to compute actual runoff (R) in these Sub-basins, and should also include the measured ungauged drainage areas used for such computation.

The Engineering Committee will use the following formula to calculate runoff for the Arkansas River Sub-basin:


Qa= Total annual discharge originating from the Arkansas River Sub-basin.

QV= Total annual discharge of the Arkansas River immediately below the mouth of Lee Creek presently measured at the Van Buren gauging station.

Qm= Total annual discharge of the Arkansas River immediately below the mouth of the Grand Neosho River, presently measured at the Muskogee gauging station.

QW= Total annual discharge of the Canadian River at Eufaula Dam, presently measured at Whitefield gauging station.

Q2= Total annual outflow from the Illinois River Sub-basin.

Q3= Total annual outflow from the Lee Creek Sub-basin.

Q4= Total annual outflow from the Poteau River Sub-basin.

*The Engineering Committee will obtain data, as available, from the USGS website ( for the following gauges (Table 1):

Table 1. Current USGS gauges used for Computation of Runoff at Sub-basins in the Compact Area


USGS Gauges Required

Drainage Area (mi2)

Spavinaw Creek

07191220 - Spavinaw Creek near Sycamore, OK



07195855 - Flint Creek near West Siloam Springs, OK


Illinois River

07195500 - Illinois River near Watts, OK



07196900 - Baron Fork at Dutch Mills, AR


Lee Creek

07249985 - Lee Creek near Short OK



07247015 - Poteau River at Loving, OK


Poteau River

07247250 - Black Fork below Big Creeknr Page, OK



07247250 - James Fork near Hackett, AR



07194500 - Arkansas River near Muskogee, OK


Arkansas River

07245000 - Canadian River near Whitefield, OK



07250550 - AR River at J. W. Trimble L& D nr Van Buren, AR


a Does not include 25.1 sq. miles of ungauged drainage.

b Does not include 13.0 sq. miles of ungauged drainage.

c Does not include 35.2 sq. miles of ungauged drainage.

d Includes 22,200 sq. miles of drainage area in Kansas that "probably is noncontributing".

Data obtained from the eleven (11) above listed gauges is sufficient to accurately compute actual runoff from the Sub-basins, but different gauges could be used for the computation of runoff.

Review of the Poteau River Sub-basin indicates that there are large portions of runoff that originate in Arkansas but are not included in the gauging. Calculations should be completed to estimate the runoff for these areas using the following equation.


RU= Calculated runoff at the OK-AR state line from ungauged contributing streams

Rm= Measured runoff at the gauge

AG= Contributing area at the gauge

AU= Area contributing runoff for ungauged streams

*Actual runoff should be computed on an annual basis, and monthly values should be included in the annual yields report as appendices, instead of the daily time series that has been included in previous reports. Units should be consistent, preferably in acre-feet (AF). Flows originating from outside the Compact area should not be included in the computation of actual runoff, unless specified in the Compact. Article II of the Compact defines the drainage areas for each Sub-basin as waters originating in the Compact area. In previous reports, return flows from the White River Basin have been removed from the flow originating in the Arkansas River Basin since the water is being transferred in from another basin. The return flow data is obtained from the water departments of the cities of Fayetteville, Rogers, and Springdale, AR.

2. Computation of Total Depletions or Accretions in each of the respective Sub-basins

The total annual depletion in each Sub-basin will be the sum of the following:

(a) Total stream diversions minus return flows,

(b) Depletions and/or accretions by major reservoirs,

(c) Evaporation losses from other than major reservoirs, and

(d) Pumpage of ground water alluvium aquifers. Data sources and procedures suggested for computation of these items are described as follows:

a) Total stream diversions minus return flows

Diversions from the Oklahoma side of the Compact, i.e. the Arkansas Sub-basin and the Oklahoma portion of the Lee Creek Sub-basin, should be estimated using information from the Oklahoma Water Resources Board (OWRB). Likewise, diversions from the Arkansas side of the Compact should be obtained from the Arkansas Natural Resources Commission (ANRC). These agencies manage the surface water rights in their respective states, and can provide information on the type of uses, allocated amounts, annual reported use, and estimates of return flows. Values of annual diversions for each sub-basin should be included in the report, along with a brief description of the methods and assumptions used in the calculation of return flows.

b) Depletions and/or accretions by major reservoirs

The Compact defines depletion as the difference between the inflow and outflow, using the following equation:

in which

I - O= Depletion in the reservoir.

P = Precipitation on reservoir surface.

p= Runoff that would have occurred from area covered by reservoir, computed by a derived rainfall-runoff factor c times P, or cP.

[]S= Change in storage volume at beginning and end of period E = Evaporation from reservoir surface.

D=Direct diversions from reservoir storage, not included in outflow; seepage from reservoir may also be a factor, and if not included in measured outflow as at gauging station below dam, should be estimated.

The Engineering Committee will obtain monthly_data for the reservoirs of the Compact area from the USACE web page, at Available data includes reservoir contents, as well as evaporation and precipitation measured over the reservoir surface.

* Precipitation on reservoir surface (P)

The Engineering Committee will obtain monthly values of precipitation data measured over the lakes from the USACE webpage.

* Runoff (p)

This component should be estimated as the product of precipitation (P) and a runoff coefficient. A runoff coefficient of 0.18 has been used since 1974 to determine the runoff quantity. It has been noted that the runoff coefficient value can vary depending on publications and that there is no way to know what existed in the area before the reservoirs were built. For these reasons it is agreed upon by the Engineering Committee to continue the use of 0.18 as the runoff coefficient since this is the value that has been used in all of the previous reports.

* Change in Storage (AS)

Change in storage is defined in the compact as the "Change in the storage volume at the beginning and end of a period", which for the water year would be computed as the difference between the contents at the end of the period (September 30th) minus the contents at the beginning of the period (October 1, previous calendar year).

Evaporation from reservoir surface (E)

The Engineering Committee will obtain monthly values of evaporation strictly measured over the lakes from the USACE webpage. Pan evaporation is used to estimate the evaporation from lakes. There is a correlation between lake evaporation and pan evaporation. Evaporation from a natural body of water is usually at a lower rate because the body of water does not have metal sides that get hot with the sun, and while light penetration in a pan is essentially uniform, light penetration in natural bodies of water will decrease as depth increases. Pan coefficients can vary depending on a number of different variables, including ground cover, levels of relative humidity, and 24 hour wind speed. Previous reports have used a pan coefficient of 0.70 for correlation between reservoir evaporation and pan evaporation.

Further discussion as to the coefficient value that should be used is required by the engineering committee.

* Direct Diversions from reservoir surface (D)

Direct diversions from reservoir storage, not included in the outflow, should be computed using information from the OWRB water rights database. Previous reports only used data from the USACE, but did not include details such as the type of use, the year of the data, and if any return flows had been included in the computation.

c) Evaporation losses from other than major reservoirs

This item has not been addressed in previous reports. The Compact states that "Evaporation from small lakes, such as those not designed for water supply, including flood-detentions structures, farm ponds, and recreation lakes, may be estimated on basis of average water surface area and appropriate data from evaporation-pan records."

Further discussion about the data sources and feasibility of including this item in the computation of depletions needs to be discussed by the Engineering Committee. Inclusion of this item in the computation of depletions will be determined by the Engineering Committee.

d) Pumpage of ground water from alluvium aquifers

This item has not been included in previous reports. The Compact states that Pumpage from stream alluviums may cause appreciable depletions in the stream flow. This is not believed to be a factor at the present (1969) time, but could conceivably be in the future for some stream reaches" (Appendix I, Item 2, page 119).

Inclusion of this item in the computation of depletions will be determined by the Engineering Committee.

Figure 1. Map of the Oklahoma-Arkansas River Compact Area


The following state regulations pages link to this page.