ST. PAUL (AP) — Operators of the Twin Cities area’s sewage system says “flushable” wipes are causing headaches for crews having to remove the products to keep pumps and pipes unclogged.

The Metropolitan Council Environmental Services said Wednesday that the wipes aren’t dissolving in sewer pipes. Tim Keegan, a sewer system manager, said in an online post for the agency that it’s spending a significant amount of time and money removing wipes and “other non-flushable materials” such as rags and dental floss.

The Minnesota city of Wyoming sued six makers of the wipes in April, saying they cause clogs in sewer systems and wastewater plants.

Kimberly-Clark spokesman Bob Brand said the company, which is named in the lawsuit, does “extensive testing” and that its wipes “do break down.”