The provisions of Sections 63.168-63.169 of this code do not apply to:
(1) improvements carried out and performed by the United States;
(2) calamities or emergencies which make it necessary to act at once to preserve the property of the district;
(3) unforeseen damage to district property, machinery, or equipment or necessary emergency repairs to them; or
(4) contracts for personal or professional services or work done by the district and paid for by the day as the work progresses.
Official text of the Texas Water Code as published by the Texas Legislative Council.