The News Tribune editorial referred to a Moody's report about implications of Tacoma's Prop 1 and how it affects rates.
Here's a concise interpretation from reading the report, which you can also do below:
PROP 1 PASSES
Action: Pass-on 2% tax increase -> rates increase
Action: Don't pass-on 2% tax increase -> bond rating falls -> rates increase
PROP 1 FAILS
Action: No tax increase -> no rate increase