The Commissioner is authorized to develop construction programs for facilities for the mentally retarded and community mental health centers for the mentally ill, which shall be based respectively on Insular-wide inventories of existing facilities for the mentally retarded and the mentally ill and surveys of need, and which shall provide in accordance with regulations prescribed under the Federal Act, for facilities which will provide adequate service for the mentally retarded and adequate community mental health services for the people residing in this territory and for furnishing needed services to persons unable to pay therefor.