Conowingo Dam (File)

A plan to reduce sediment and nutrient spillage into the bay through the Conowingo Dam has moved to the next phase as the state searches for companies with innovative ideas to dredge behind the nearly 90-year old facility.

The request for proposals announced Thursday by the Maryland Environmental Service seeks companies interested in participating in a pilot program to show their solutions to remove sediment are both viable and cost effective for the state.

Gov. Larry Hogan announced last month that he would seek proposals following a meeting of a Conowingo Dam Workgroup.

Earlier this year about a dozen companies submitted ideas for how they would each remove the sediment and then reuse it or dispose of it.

The ideas ranged from dumping the dredge spoils in the ocean to reusing the material for counter tops and pavers.

A two-year old study by the United State Geological Survey estimated that the dam was at 92 percent of its nearly 200 million pounds of sediment retention capacity.  A similar study just three years earlier noted that the dam was already allowing phosphorous and nitrogen to pass downstream into the Chesapeake Bay.

Hogan, speaking in early August, painted a more dire picture of the dam and the nutrients now polluting the bay.

“The Conowingo Dam has reached capacity and is no longer able to trap sediment, which, if allowed to flow downstream, could increase pollution and negatively impact the bay,” Hogan said.

Hogan campaigned in 2014 on reducing pollution caused by the dam.

The hydroelectric dam, completed in 1928, sits on the Susquehanna River approximately 10 miles from where it joins the Chesapeake Bay.

The river, the longest on the East Coast, is the bay’s largest tributary and provides about half the fresh water to the estuary. It’s also responsible for about half of the nitrogen pollution that flows into the bay.

Much of that pollution, however, comes from other states as the Susquehanna flows 464 miles through New York and Pennsylvania.