Tex. Water Code § 15.917

After the executive administrator approves the engineering plans, a political subdivision or water supply corporation may not make any substantial or material alteration in the plans unless the executive administrator authorizes the alteration. The executive administrator shall review and approve or disapprove plans and specifications for all sewage collection, treatment, and disposal systems for which financial assistance is provided from the fund in a manner that will satisfy commission requirements for design criteria and permit conditions that apply to construction activities.