Each regional water authority and each regional water district shall, annually, submit to the Public Utilities Regulatory Authority, on or before May thirty-first, its annual report for the preceding calendar year, in such form and manner as the authority may prescribe. The authority may, for good cause shown, grant an extension of such deadline of up to sixty days, provided the regional water authority or regional water district desiring an extension files a request in writing setting forth the reasons for such request.