Tex. Water Code § 26.014
The members of the commission and employees and agents of the commission are entitled to enter any public or private property at any reasonable time for the purpose of inspecting and investigating conditions relating to the quality of water in the state or the compliance with any rule, regulation, permit or other order of the commission. Members, employees, or agents of the commission and commission contractors are entitled to enter public or private property at any reasonable time to investigate or monitor or, if the responsible party is not responsive or there is an immediate danger to public health or the environment, to remove or remediate a condition related to the quality of water in the state. Members, employees, commission contractors, or agents acting under this authority who enter private property shall observe the establishment's rules and regulations concerning safety, internal security, and fire protection, and if the property has management in residence, shall notify management or the person then in charge of his presence and shall exhibit proper credentials. If any member, employee, commission contractor, or agent is refused the right to enter in or on public or private property under this authority, the executive director may invoke the remedies authorized in Section 26.123 of this code.
Tex. Water Code § 26.014