Tex. Water Code § 49.216

(a) A district may contract for or employ its own peace officers with power to make arrests when necessary to prevent or abate the commission of:

(1) any offense against the rules of the district when the offense or threatened offense occurs on any land, water, or easement owned or controlled by the district;

(2) any offense involving injury or detriment to any property owned or controlled by the district; and

(3) any offense against the laws of the state.

(b) A district may appoint reserve peace officers who may be called to serve as peace officers by the district during the actual discharge of their official duties.

(c) A reserve peace officer serves at the discretion of the district and may be called into service if the district considers it necessary to have additional officers to preserve the peace in or enforce the law of the district.

(d) A reserve peace officer on active duty and actively engaged in assigned duties has the same rights, privileges, and duties as any other peace officer of the district.

(e) Any peace officer who is directly employed by a district, before beginning to perform any duties and at the time of appointment, must take an oath and execute a bond conditioned on faithful performance of such officer's duties in the amount of $1,000 payable to the district. The oath and the bond shall be filed in the district office.

(f) A peace officer contracted for by the district, individually or through a county, sheriff, constable, or municipality, is an independent contractor, and the district is responsible for the acts or omissions of the peace officer only to the extent provided by law for other independent contractors.