MILWAUKEE (WTAQ) - The soil was saturated when more heavy rain fell in the Milwaukee area last week.
That led to nearly 525 million gallons of untreated wastewater being dumped into local rivers and Lake Michigan.
Local officials say all the moisture overwhelmed sewers and the deep tunnel.
Overflows started last Thursday morning in an effort to head off possible backups of sewage in basements. That overflow was the second of this year and the first since June 2011.
A state permit allows the Milwaukee Sewerage District six combined sewer overflows each year.