Tex. Water Code § 11.144

All holders of permits and certified filings shall obtain the approval of the commission before making any alterations, enlargements, extensions, or other changes to any reservoir, dam, main canal, or diversion work on which a permit has been granted or a certified filing recorded. A detailed statement and plans for alterations or changes shall be filed with the commission and approved by the executive director before the alterations or changes are made. This section does not apply to the ordinary maintenance or emergency repair of the facility.