Why Maryland, Virginia residents may pay for the sewage spill

State of play: DC Water estimates repairs and cleanup of the Potomac Interceptor will run about $20 million.

• Federal aid will cover 75% of that — and the money will go to D.C.
• DC Water's CEO has said he doesn't expect spill-related increases for city customers. Rates were already set to rise before the collapse.

Friction point: DC Water is like a contractor in this case — responsible for maintaining and repairing the 54-mile sewer line from Dulles to Blue Plains. The other utilities that share the line must pay for the work under a regional agreement, the Banner reports.

• That includes WSSC Water, which serves 2 million customers in Montgomery and Prince George's counties.
• Even though the collapsed section carries wastewater from just a handful of Montgomery County towns — including Glen Echo, Cabin John, Bethesda, Potomac and Rockville — all WSSC customers within a 1,000-square-mile service area share the financial responsibility, a spokesperson tells the Banner.

How it works: WSSC Water will cover about 31% of the repair costs for the collapsed section.

• Utilities in Fairfax and Loudoun counties will cover much of the rest.
• The city of Rockville is responsible for about 5% under a separate agreement.

The big picture: The spill comes as soaring utility bills are impacting people across the region.

• WSSC Water's rates were already rising before the spill, per the Banner.
• Quarterly bills rose about $25 in each of the last two fiscal years, and a planned 5% increase is still expected.

The bottom line: Dividing the repair tab after the spill is getting messy.