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Rio Grande Watermaster Program

About the Rio Grande Watermaster Program, the area under its jurisdiction, and how to contact the office.

About the Rio Grande Watermaster Program

In the Rio Grande basin above Lake Amistad (the Upper Rio Grande), water rights are managed using a “first in time, first in right” priority system, as they are in other parts of Texas. Water rights in the Middle and Lower Rio Grande are served by the Falcon-Amistad reservoir system. Water below Lake Amistad is allocated on an account basis, much like having a bank account with a constantly changing balance. Priority is given to all municipal accounts, which means that at the beginning of each year the storage balance for each municipal account resets to its full authorized water-right amount. The municipal priority is guaranteed by the monthly reestablishment of a municipal reserve in the system of 225,000 acre-feet, which is equivalent to one year of average diversions for all municipal demands below Amistad for Texas users.

Irrigation accounts, on the other hand, must rely on balances that are carried forward, as irrigation accounts are not reset at the beginning of the year. Each month the watermaster determines how much unallocated water assigned to the United States is contained in the Falcon-Amistad system. If surplus water is identified in a given month, it is allocated to the irrigation accounts. When water is used, it is subtracted from the respective account by type of use from the account’s usable balance. This system of accounting for water usage was put in place after an international treaty with Mexico was established, and in accordance with a 1969 District Court ruling.

How to Contact the Rio Grande Watermaster’s Office

Rio Grande Watermaster
1804 West Jefferson Avenue
Harlingen, Texas 78550-5247
Voice: (956) 430-6056 or Toll Free: (800) 609-1219
Fax: (956) 430-6052


River BasinCounties
Rio Grande Brewster, Cameron, Dimmit, Hidalgo, Hudspeth, Jeff Davis, Jim Hogg, Kinney, Maverick, Presidio, Starr, Terrell, Val Verde, Webb, Willacy, Zapata

Offers to Sell or Contract Water in the Rio Grande

Currently there are no offers to sell or contract water. If you have any questions, please contact the Rio Grande Watermaster at (956) 425-6010 or toll free at (800) 609-1219.