Unfortunately, Stephen, neither, COJ or JEA, sets the rates on their bonds. The rates and specifically the yields are set by the market.
undeniably, the JEA, with the full participation of COJ, racked up a lot of debt in the past decades ... more so than almost any other similar utility as noted in the credit rating agencies analysis of JEA.
The only solution to that problem is to pay off the debt which JEA has been doing, see the reference in the article posted. As JEA improves its balance sheet, operating margins and debt loads, its credit rating will increase and consequently, the interest cost on any future bonds will be reduced by the market as an acknowledgement of that.
The only thing we can hope for is like I said no rate increase with the imposition of a new tax. Any rate reduction the JEA customers would have conceivably hoped for will instead be pledged to reduce the City's pension obligations.