(a) The aggregate principal amount of bonds and notes issued by the authority may not exceed $500 million outstanding at any one time: Provided, That before the authority issues bonds and notes in excess of $400 million the Legislature must pass a resolution authorizing this action: Provided, however, That in computing the total amount of bonds and notes which may at any one time be outstanding, the principal amount of any outstanding bonds or notes refunded or to be refunded either by application of the proceeds of the sale of any refunding bonds or notes of the authority or by exchange for any refunding bonds or notes, shall be excluded.

(b) In addition to the amounts authorized by subsection (a) of this section, the Water Development Authority may issue, pursuant to section seventeen-b, article fifteen-a, chapter thirty-one of this code, bonds or notes in the aggregate principal amount not to exceed $180 million. This authorization is for the limited purpose of providing grants for capital improvements for publicly owned wastewater treatment facilities with an authorized permitted flow of four hundred thousand gallons per day or more which are required to maintain compliance with certain standards for discharges into watersheds in accordance with said section seventeen-b.