Tex. Water Code § 15.604

(a) The board may use the revolving fund for financial assistance only as provided by the federal act:

(1) to make loans, on the conditions that:

(A) the loan is made at or below market interest rates, including an interest-free loan;

(B) principal and interest payments will begin not later than one year after completion of the project to be financed and the loan will be fully amortized not later than the expiration date of the term of the loan;

(C) the recipient of the loan will establish a dedicated source of revenue for repayment of the loan; and

(D) the revolving fund will be credited with all payments of principal of and interest on the loan;

(2) to buy or refinance the debt obligation of political subdivisions at or below market rates if the debt obligations were incurred after March 7, 1985;

(3) to guarantee or purchase insurance for political subdivisions if the guarantee or insurance would improve access to market credit or reduce interest rates;

(4) as a source of revenue or security for the payment of principal and interest on bonds issued by the state if the proceeds of the sale of those bonds will be deposited in the revolving fund;

(5) to provide loan guarantees to similar revolving funds established by municipalities or intermunicipal agencies;

(6) to earn interest on revolving fund accounts;

(7) for the reasonable costs of administering the revolving fund and conducting activities provided for by Title VI of the federal act, except that those amounts may not exceed the amount authorized under Title VI of the federal act; and

(8) for other purposes as provided by the federal act.

(b) The board shall adopt rules specifying the manner in which any additional state revolving fund hereafter established by the board, or any capitalization grant under the state water pollution control revolving fund, the safe drinking water revolving fund, or any additional state revolving fund, may be used to provide financial assistance to an eligible applicant for public works. Such rules shall require financial assistance to be provided for the purpose or purposes and on the terms authorized by the federal legislation or federal agency program under which the additional state revolving fund was established or the capitalization grant was awarded.