Texas Water Code - WATER § 11.313. Filing Contests

(a) Any water right claimant affected by the preliminary determination, including any claimant to water rights within the river basin but outside the stream or segment under adjudication, who disputes the preliminary determination may within the time for filing contests prescribed by the commission in the notice, including any extension of the time, file a written contest with the commission, stating with reasonable certainty the grounds of his contest.

(b) The statement filed to contest a preliminary determination must be verified by an affidavit of the contestant, his agent, or his attorney.

(c) If the contest is directed against the preliminary determination of the water rights of other claimants, a copy shall be served on each of these claimants or his attorney by certified mail, and proof of service shall be filed with the commission.