A Kennewick Irrigation District official said a bank error caused about 50 KID customers' payments on water bills to not be recorded as having been paid.
The mistake is being corrected, and the affected customers will not be charged interest or late payment fees, said Rob Schunk, KID's customer accounts supervisor.
The problem was discovered when KID customers who used a bill-pay service to pay their first installments before the April 15 due date began complaining about receiving late payment notices.
Schunk said it appears the customers' accounts that were affected were from one day's receipts of bill-pay payments.
"We've been communicating this (explanation) to our customers," he said.