2017 sewage overflow from Milwaukee into Lake Michigan the lowest in decades

MILWAUKEE (CBS 58) -- The Milwaukee Metropolitan Sewerage District (MMSD) recycled 72 billion gallons of dirty water last year that was cleaned and returned to Lake Michigan. Out of all the water MMSD receives they cleaned and returned 99.999998%.

The 99.9% is the highest clean percentage since 2012 when it was also 99.9%. In 2016, 99.8% was cleaned and in 2015 the percentage was 98.9%.

Milwaukee ran above-normal for precipitation for most of the year until the middle of December. The year ended 0.67" below-normal for precipitation.

On July 12, one regional sewer did overflow 1,450 gallons of untreated wastewater into Lake Michigan. On that day Milwaukee picked up 1.68" of rain which was the most for any day in 2017.

The sewage overflow in 2017 was the least since the deep tunnel was put into operation in 1994.