An endangered mussel could force part of a Flint water pipeline deeper underground and make the project more expensive.
The project will allow the city to get its drinking water directly from Lake Huron instead of through a Detroit pipeline. The Flint River will be used as a water source until the new pipeline is finished.
Since the Northern Riffleshell Mussel is endangered, federal regulations require that the creatures are not disturbed.
"They would like us to do basically a shaft on each side of the river and then tunnel underneath the river and we're proposing an open cut," said John O'Brien with the Genesee County Drain Commission, a member of the Karegnondi Water Authority.
The Black River in Sanilac County is one place that could require additional work.
Crews have to cross more than 280 rivers and streams to build the 65 mile long pipeline.
If the tunnel is required, K.W.A. will have to spend more than 200,000 dollars more on the cost of the project.
Project managers say the tunnel would not delay the overall completion date for the pipeline and new water plant. Those should both be completed by May of 2016.