THE STATE OF TAMIL NADUversusTHE STATE OF KARNATAKA & ANR

                  [2026] 2 S.C.R. 285 : 2026 INSC 113

                       The State of Tamil Nadu
                                   v.
                     The State of Karnataka & Anr.
                         (Original Suit No. 1 of 2018)
                               02 February 2026
                 [Vikram Nath* and N.V. Anjaria, JJ.]


                            Issue for Consideration
       Matter pertains to dispute as regards the sharing of the waters
       of the Pennaiyar River between the State of Tamil Nadu and the
       State of Karnataka.

                                   Headnotes†
       Inter-State River Water Disputes Act, 1956 – ss.3, 4 – Inter-
       State River Pennaiyar – Dispute as regards the sharing
       of the waters of the Pennaiyar River and arising from the
       alleged construction of a check dam/diversion by the State
       of Karnataka-defendant-State on the said river, impeding
       the free flow of water, thereby depriving the State of Tamil
       Nadu-plaintiff-State of the benefits of the river waters flowing
       through the territories of Tamil Nadu and Karnataka and
       thereafter into Puducherry – Suit by the plaintiff-State against
       defendant-State and the Union of India seeking declaration
       that the said unilateral action of the defendant-State, illegal
       and violates the fundamental rights of the inhabitants of the
       plaintiff-State; grant permanent injunction restraining the
       defendant-State, from proceeding with the construction of
       Check Dam/diversion structure across the Pennaiyar river and
       its tributaries, and pumping water from them to the existing
       tanks in the Pennaiyar basin by the defendant-State; and
       other directions:
       Held: Pennaiyar River water dispute has been pending consideration
       before this Court since the year 2018 – Multiple efforts have been
       undertaken by the concerned stakeholders to bring about an
       amicable resolution of the dispute – However, the negotiation
       process has not yielded any mutually acceptable outcome – In
       view of the inability of the parties to arrive at a common settlement,


* Author
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       appropriate to call upon the Central Government to constitute a
       tribunal in terms of the statutory framework, so that the dispute
       may be adjudicated in accordance with law – In addition, the
       affidavit filed by the Union records that, during the ministerial-
       level negotiations, the plaintiff-State unequivocally conveyed that
       the Pennaiyar River water dispute ought to be resolved through
       adjudication by a Tribunal and in view thereof, the defendant no.2
       took a decision to indefinitely defer the negotiation process –
       Thus, issuance of direction to the Central Government to issue an
       appropriate notification in the Official Gazette and to constitute a
       Water Disputes Tribunal for the adjudication of the inter se water
       dispute between the parties, within the one month from the date
       of judgment. [Paras 7-10]

                                 Case Law Cited
       T.N. Cauvery Neerppasana Vilaiporulgal Vivasayigal Nala Urimai
       Padhugappa Sangam v. Union of India [1990] 3 SCR 83 : (1990)
       3 SCC 440 – referred to.

                                   List of Acts
       Constitution of India; Supreme Court Rules, 2013; Inter-State River
       Water Disputes Act, 1956.

                                List of Keywords
       Pennaiyar River; Inter-State River Pennaiyar dispute; Construction
       of check dam/diversion; Impeding free flow of water; Construction
       of Check Dam/ Anicut across Markandeyanadhi near Yargol village,
       Bangarapettai Taluk.

                               Case Arising From
       CIVIL ORIGINAL JURISDICTION: Original Suit No. 1 of 2018
       Original Suit has been instituted under Article 131 of the Constitution
       of India

                            Appearances for Parties
       Advs. for the Plaintiff(s):
       V. Krishnamurthy AAG/Sr. Adv., P. Wilsson, N.R. Elango,
       G. Umapathy, Sr. Advs., Ms. Misha Rohatgi, Nakul Mohta, Amulya
       Upadhyay, Ayush Kashyap, Ms. Azka Sheikh Kalia, Sachin S.
[2026] 2 S.C.R.                                                            287

        The State of Tamil Nadu v. The State of Karnataka & Anr.


     Adv. for the Defendant(s):
     Ms. Aishwarya Bhati, A.S.G., Shashi Kiran Shetty, Advocate
     General, Shyam Divan, Mohan V Katarki, Sr. Advs., Ms. Chitrangda
     Rastravara, Pratyush Shrivastav, Sachin Sharma, Navanjay
     Mahapatra, Dr. N. Visakamurthy, Nishanth Patil, Mayank Jain,
     Ms. Addoorya Harish, Nishanth Patil.

                 Judgment / Order of the Supreme Court

                                 Judgment

     Vikram Nath, J.

1.   The present suit has been instituted by the State of Tamil Nadu
     (hereinafter referred to as the “plaintiff-State”) invoking the original
     jurisdiction of this Court under Article 131 of the Constitution of India,
     read with Part III of the Supreme Court Rules, 2013, against the
     State of Karnataka (hereinafter referred to as the “defendant-State”)
     and the Union of India (hereinafter referred to as “defendant no. 2”),
     praying, inter alia, the grant of the following reliefs.: -
           (a)   Declare that the unilateral action of the defendant-
                 State, in proceeding to construct/ having proceeded
                 to construct new Check Dams/ Dams and diversion
                 structures across the Pennaiyar river its tributaries,
                 Streams etc. to divert the water by gravity or
                 pumping, and pumping from tanks surplusing into
                 the Pennaiyar river or its tributaries without obtaining
                 the prior consent of the plaintiff-State is illegal and
                 violates the fundamental rights of the inhabitants of
                 the plaintiff-State;
           (b)   Grant permanent injunction restraining the defendant-
                 State, from proceeding with the construction of Check
                 Dam/ Anicut across Markandeyanadhi near Yargol
                 village in Bangarapettai Taluk and construction of
                 check dam/diversion structure across the Pennaiyar
                 river and its tributaries, and pumping water from them
                 to the existing tanks in the Pennaiyar basin by the
                 defendant-State;
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            (c)   Direct the defendant-State to ensure the natural
                  flows in the Pennaiyar river and its tributaries to the
                  Plaintiff State; and
            (d)   Grant mandatory injunction directing the defendant-
                  Union to take action on the plaintiff-State’s letter
                  dated 16.03.2018 with reference to construction of
                  Dams and diversion structures and pumping schemes
                  undertaken by the defendant-State in the Pennaiyar
                  river; and
            (e)   Pass such further decree or decrees or order or orders
                  as this Hon’ble Court may deem fit and proper in the
                  facts and circumstances of the case.
2.     The facts, insofar as they are relevant and material for the adjudication
       of the controversy at hand, are set out hereinafter:
       2.1. The plaintiff-State and the defendant-State are riparian States,
            being two among the three basin States, along with the Union
            Territory of Puducherry, through which the inter-State River
            Pennaiyar flows. According to the plaintiff-State, the dispute
            centres around the sharing of the waters of the Pennaiyar
            River and arises from the alleged construction of a check dam/
            diversion by the defendant-State on the said river, which is stated
            to have impeded the free flow of water, thereby depriving the
            plaintiff-State of the benefits of the river waters flowing through
            the territories of Tamil Nadu and Karnataka and thereafter into
            Puducherry.
       2.2. In the year 1892, with a view to delineate and acknowledge the
            extent of the rights of the party-States in relation to the use,
            control and distribution of the waters of an inter-State River, an
            agreement came to be executed between the erstwhile States
            of Madras and Mysore, the predecessor States of the present
            plaintiff-State and defendant-State, respectively.
       2.3. According to the plaintiff-State, the dispute arose upon the
            defendant-State taking a decision to undertake five distinct
            works in the Pennaiyar River Basin within its territory. It is
            alleged that the execution of these works would interfere with
            the natural flow of the river, resulting in a substantial reduction
            of the waters reaching the plaintiff-State and thereby adversely
[2026] 2 S.C.R.                                                          289

         The State of Tamil Nadu v. The State of Karnataka & Anr.


             impacting its water requirements. It is further asserted that the
             said projects have the potential to gravely affect the livelihood
             of lakhs of farmers in the districts of Krishnagiri, Dharmapuri,
             Thiruvannamalai, Villupuram and Cuddalore in the plaintiff-State.
     2.4. In this context, the Chief Secretary of the plaintiff-State called
          upon the defendant-State to adhere to the Agreement of 1892,
          contending that, in terms thereof, no such works could have
          been undertaken by the defendant-State on the inter-State
          River without obtaining the prior consent of the plaintiff-State.
     2.5. Subsequently, the plaintiff-State became aware that the
          defendant-State was proposing to construct check dams across
          a tributary of the River Pennaiyar. On 22nd May, 2013 when
          officials of the plaintiff-State conducted a field inspection of the
          site, they submitted a report recording that preliminary works
          relating to the construction of the dam had commenced, a fact
          which was further corroborated by the display board erected
          at the site.
     2.6. Ultimately, vide communication dated 1 st July, 2013, the
          defendant-State responded to the concerns raised by the
          plaintiff-State. In the said reply, the defendant-State asserted
          that the Agreement of 1892 was merely a political arrangement
          entered into in the prevailing regime of that period and had
          ceased to have effect upon the attainment of independence
          by the Union of India. On that premise, it was contended by
          the defendant-State that no consent of the lower riparian State,
          namely the plaintiff-State, was required.
     2.7. Aggrieved by what is alleged to be the unilateral refusal of the
          defendant-State to comply with and act in accordance with the
          Agreement of 1892, the plaintiff-State approached this Court
          by instituting the present suit through a plaint dated 18th May,
          2018. The pleadings stood completed upon the filing of the
          replication by the plaintiff-State on 7th May, 2019.
     2.8. During the pendency of the present suit, the plaintiff-State filed
          an interlocutory application1, seeking, inter alia, the issuance
          of the following directions: -


1   I.A. No. 95384 of 2019
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                     “a. restrain the defendant-State and its instrumentalities
                     from proceeding further with the construction of dam
                     across Markandeyanadhu near Yargol Village;
                     b. direct the defendant-State and its instrumentalities
                     not to obstruct the natural flows to the downstream
                     plaintiff-State pending the disposal of the present
                     application.”
       2.9.     This Court, vide order dated 14th November, 2019, dismissed
                the said application and declined to grant any interim relief,
                primarily on the ground that nearly 75% of the construction
                work had already been completed by the defendant-State and
                that the material on record prima facie indicated that the project
                in question had been undertaken after obtaining all requisite
                sanctions and permissions. However, the plaintiff-State was
                granted liberty to move an appropriate application invoking
                the powers of the Central Government for the constitution of
                an Inter-State River Water Disputes Tribunal in accordance
                with the provisions of the Inter-State River Water Disputes
                Act, 1956.
       2.10. On 30th November, 2019 the plaintiff-State lodged a complaint
             under Section 3 of the Inter-State River Water Disputes Act,
             1956, calling upon the Central Government to constitute a
             Tribunal for the adjudication of the Pennaiyar River water
             dispute.
3.     In pursuance thereof, the process for the constitution of an Inter-
       State River Water Disputes Tribunal commenced under the aegis
       of the Central Government. In the interregnum, the plaintiff-State
       filed a further application2 dated 16th December, 2019, before this
       Court, seeking a direction to the Central Government to constitute
       an Inter-State River Water Disputes Tribunal.
4.     Upon the negotiation process having been undertaken and no
       amicable resolution having been arrived at between the parties,
       defendant no. 2 filed an affidavit dated 2nd January, 2025, before
       this Court, stating that: -


2    I.A. No. 193417 of 2019
[2026] 2 S.C.R.                                                              291

        The State of Tamil Nadu v. The State of Karnataka & Anr.


           “6. It is further submitted that this report is concluded that
           the Committee made sincere attempts to resolve the issue
           amicably between States of Tamil Nadu and Karnataka
           through discussions on multiple dates. The Committee
           has suggested some solutions to resolve the dispute.
           However, in view of the firm stand taken by the Govt. of
           Tamil Nadu, no consensus could be reached between two
           States on solutions.
           7. . . . it was decided, as a last effort, to organise a meeting
           of the Water Resource Ministers of both States to try and
           create a consensus on the solutions suggested by the
           Negotiation Committee. . . .”
5.   Thus, negotiations in respect of the Pennaiyar River water dispute
     were initiated at the ministerial level. However, on 7th October, 2025
     defendant no. 2, coordinating the negotiations between the plaintiff-
     State and the defendant-State, filed an additional affidavit before
     this Court stating that the earlier proposed meeting at the ministerial
     level had been postponed indefinitely. The relevant extract of the
     said affidavit reads as under: -
           “5. . . . First meeting notice was issued to all party states
           for meting scheduled on 19.12.2024 at Ministers level but
           did not take place due to request of State of Karnataka
           to postpone the same as Winter Session of Karnataka
           Legislature Assembly was going during that period. . . .
           6. It is submitted that as per tire direction of competent
           Authority, a preliminary meeting was held with the officials
           of party States under the Chairpersonship of Secretary
           (DoWR, RD&GR), on 03.03.2025. During the meeting, the
           Karnataka, reiterated that it has agreed for a total 15%
           release of water including 7.5% from Yargol dam and
           7.5% from other tributary (Masti Sub-Basin), at the border,
           expressed interest to iron out any differences through
           negotiations. On the other hand, the Tamil Nadu stood
           to its position that a Tribunal be constituted for the
           resolution of dispute.
           7. It is submitted that Second Meeting notice was issued
           to all party states for meeting scheduled on 18.03.2025
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            at Ministers Level. However, the Tamil Nadu expressed
            an opinion that any further negotiation would only
            delay the constitution of the Tribunal and stated that
            there is no need for any further negotiation at the
            level of Hon’ble Minister of Water Resources of the
            States. Further, the State of Tamil Nadu has reiterated
            its stand for constitution of Tribunal to resolve the
            Pennaiyar Water Dispute vide its communication dated
            15.03.2025. . . .
            8. It is submitted that in view of the opinion and stand
            taken by the Tamil Nadu, the proposed meeting [on
            18.03.2025] at Ministers level has been postponed
            indefinitely vide DOWR, RD&GR dated 17.03.2025. . . .”
                                                       (emphasis laid)

6.     We have heard Mr. V. Krishnamurthy and Mr. P. Wilson, learned
       Senior counsel for the plaintiff-State of Tamil Nadu, Mr. Shyam
       Diwan and Mr. Mohan V. Katarki learned Senior counsel, along with
       Mr. Shashi Kiran Shetty, learned Advocate-General, appearing for
       the defendant-State of Karnataka and Ms. Aishwarya Bhati, learned
       Additional Solicitor General, appearing for defendant no. 2 - Union
       of India.
7.     The present Pennaiyar River water dispute has been pending
       consideration before this Court since the year 2018. Multiple efforts
       have been undertaken by the concerned stakeholders to bring
       about an amicable resolution of the dispute. However, we have no
       hesitation in recording that the negotiation process has not yielded
       any mutually acceptable outcome. In view of the inability of the parties
       to arrive at a common settlement, we consider it appropriate to call
       upon the Central Government to constitute a Tribunal in terms of
       the statutory framework, so that the dispute may be adjudicated in
       accordance with law.
8.     In addition, the affidavit dated 7th October, 2025, filed by defendant
       no. 2 elucidates the prevailing position on the ground with respect
       to the statutorily mandated negotiation process. The said affidavit
       records that, during the ministerial-level negotiations, the plaintiff-
       State unequivocally conveyed that the Pennaiyar River water dispute
[2026] 2 S.C.R.                                                          293

         The State of Tamil Nadu v. The State of Karnataka & Anr.


      ought to be resolved through adjudication by a Tribunal. It was in
      view of this firm stand adopted by the plaintiff-State that defendant
      no. 2 took a decision to indefinitely defer the negotiation process.
9.    This Court, in T.N. Cauvery Neerppasana Vilaiporulgal Vivasayigal
      Nala Urimai Padhugappa Sangam v. Union of India,3 has held that
      where the statutorily prescribed negotiation process conducted under
      the aegis of the Central Government fails to bring about a resolution
      of an inter-State River water dispute, it becomes imperative for the
      Central Government to constitute a River Water Disputes Tribunal,
      and to refer the dispute for adjudication to such Tribunal. The Court
      accordingly observed as follows: -
             “18. Section 4 indicates that on the basis of the
             request referred to in Section 3 of the Act, if Central
             Government is of the opinion that the water dispute
             cannot be settled by negotiation, it is mandatory for
             the Central Government to constitute a Tribunal for
             adjudication of the dispute. We were shown the Bill
             where in Section 4 the word ‘may’ was used. Parliament,
             however, substituted that word by ‘shall’ in the Act. Once
             we come to the conclusion that a stage has reached
             when the Central Government must be held to be of
             the opinion that the water dispute can no longer be
             settled by negotiation, it thus becomes its obligation
             to constitute a Tribunal and refer the dispute to it as
             stipulated under Section 4 of the Act. . . .”
                                                      (emphasis laid)

10. We, therefore, find no reason to refrain from directing the Central
    Government to issue an appropriate notification in the Official Gazette
    and to constitute a Water Disputes Tribunal for the adjudication of
    the inter se water dispute between the parties herein, within a period
    of one month from today.
11. We order as above.
12. With the aforesaid direction, the present suit stands disposed of.


3    (1990) 3 SCC 440
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13. Needless to mention that all questions, including those relating to
    the reliefs that may be available to the parties, are kept open for
    consideration by the Tribunal.

       Result of the case: Suit disposed of.




       †
           Headnotes prepared by: Nidhi Jain