Dairies fined $20,000 for manure digester project

State regulators have fined a Northwest Iowa dairy $10,000 for constructing a set of manure transport pipes months before seeking a permit for the work.

It is the second fine associated with construction of Novilla RNG's manure digester system south of Sioux Center, according to Iowa Department of Natural Resources orders.

The project consists of two large vessels that capture methane from the manure produced by three dairies. That biogas is used by Sioux Center residents to heat their water and homes and to cook food.

Novilla, a Michigan company, recently started construction on another manure digester system in Winneshiek County that is opposed by some residents. The Iowa DNR issued permits for the two digester vessels there before construction recently began on their foundations, said Mark Hill, a chief executive of Novilla.

But that was not the case near Sioux Center.

In 2023, Maassen Dairy was fined $10,000 because construction of one of Novilla's digesters and piping that connects to another dairy began without permits. The other site, now under the ownership of Highland Dairy, was recently fined $10,000 for the pipe permit violation.

The Iowa DNR noted that permits are important to ensure the project designs and locations are acceptable. In the case of the most recent violation, "there was nothing wrong with the pipeline itself," said Daniel Morse, a state environmental specialist who investigated.

The violation at the Highland site was discovered in May 2024, when Morse went to the dairy as part of the permit process. The permit had been requested early that month, but Morse discovered the pipeline already had been built — six months earlier.

The dairies — because they own the properties — were required to obtain the permits. "It was paperwork, is all it was," Hill said of the violations.

He said the system is operational and has been supplying natural gas to Sioux Center since August.

Some construction began at the Winneshiek site west of Decorah before winter arrived and stalled it, Hill said. The project has received state and county approval, although two decisions by county leaders are being challenged in court by the Driftless Water Defenders.

The group has filed two lawsuits — which are pending — that challenge the county supervisors' August vote to rezone the site and the Board of Adjustment's September approval of a conditional use permit.

"We feel confident that the legal challenges will be positively resolved and community support we received during the conditional use permit meeting and subsequent unanimous approval from the Board of Adjustment is indicative of the broader support we have in the community," Hill said.

The project includes two, 2.5-million-gallon digester vessels that will collect gas from the manure of two dairies. The Driftless group has opposed the project for its potential to allow the dairies to increase their herd sizes.

Dairy cattle produce the most manure of any livestock, and finding efficient ways to dispose of that manure can be challenging.

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