Section 2L. There shall be established and set up on the books of the commonwealth a separate fund, to be known as the Water Pollution Abatement Revolving Fund, consisting of amounts credited to the fund under chapter 29C. The fund shall be administered under said chapter 29C by the board of trustees of the Massachusetts Clean Water Trust created under that chapter and shall be held in trust exclusively for the purposes and the beneficiaries described in that chapter. The state treasurer shall be treasurer-custodian of the fund and shall have the custody of its monies and securities.