Innovative process to restore Dover’s Mirror Lake

Using activated carbon process similar to what’s used in water filters, state leaders hope to restore Dover’s Mirror Lake to its orginal, natural state.

Mirror Lake lies in the shadow of Legislative Hall in Dover and a short distance from Woodburn, the traditional home of Delaware’s sitting governor.  Some photographers have used the lake’s location to capture the reflection of Leg Hall in the water.

PCBs and mercury

But beneath the surface of that beautiful view, Mirror Lake is not nearly as pretty.  Over the years contaminants including PCBs and mercury have built up in the bottom sediments of the lake.  Beacause of that, activity around the water has been limited, and there’s been a ban on eating fish caught in its waters.

“Mirror Lake should be a jewel in Dover’s crown, but sadly over the years it’s lost some of its luster,” said State Senator Brian Bushweller, a Democrat who represents the district where the lake is located.

A unique solution

State leaders gathered in Dover Thursday to celebrate the start of a process designed to solve the pollution issues in the lake in a unique way.  The state will incorporate an activated carbon product called SediMite into the sediment at the bottom of the lake.  The SediMite uses technology similar to what is used in many water filters and will bind the contaminants in the sediment to improve the health of the lake.

“This technology demonstrates that we can, in a few short years, reverse the environmental damage that has been done in one of the most beautiful lakes in Kent County and make it fishable again,” said Department of Natural Resources and Environmental Control Secretary Collin O’Mara.

At a cost of about $1 million, using the SediMite to trap contaminants is cheaper than dredging the lake to remove contaminated sediment.  The majority of the project is being funded by the state, with the help of $73,800 in federal grant funds.

First of its kind

The Mirror Lake project is the largest application of SediMite anywhere in the U.S.  It’s also the first state-funded sediment remediation project of its kind in the nation.  “This project once again demonstrates Delaware’s innovative  leadership when it comes to restoring watersheds,” said EPA Regional Administrator Shawn Garvin.  

The SediMite process has been tested on a smaller scale at some federal facilities including Aberdeen Proving Ground in Maryland.  DNREC worked with researchers from the University of Maryland, Baltimore County to develop the solution plan.  

DNREC officials expect the lake to be restored to health in a few years, compared to the decades it would take to naturally return to its original state.