Homeowners are responsible for maintaining the alley portion behind their house.
The county has an option to repair/repave the alley which is as follows.

Contact the county to have them determine if your alley qualified.
If so, 51% of the homeowners on the alley need to agree to the repairs.
Homeowners will be charged $750 (or $50 a year for 15 years) on their annual tax bill.

Read more here.