State officials say Wisconsin farms spilled more than 1 million gallons of manure this year, the greatest amount in seven years.
Manure handling is a volatile issue in Wisconsin as dairy farms grow larger.
An analysis by the Milwaukee Journal Sentinel shows about one-third of the spills since 2007 came from farms with 700 or more cows. Wisconsin has nearly 200 large-scale livestock operations.
State Department of Natural Resources records show the second largest volume in spills happened in 2008 when 905,000 gallons were released.
In the latest spill, 300,000 gallons of manure spilled from a ruptured pipe Nov. 24 at a facility in Dane County that uses farm waste to produce electricity. The break sent manure into Six Mile Creek.