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EPA in Delaware

Mirror Lake Reflects ‘Significant Improvement’

Stories of Progress in Achieving Healthy Waters

U.S. EPA Region 3 Water Protection Division

Dover, Delaware • February 26, 2015

Delaware officials report a 60 percent baseline reduction of contaminants in fish, water and sediment one year after an EPA-aided restoration project at Mirror Lake in Dover, Delaware.

Scientists from the Delaware Department of Natural Resources and Environmental Control (DNREC) like what they see when they look into Mirror Lake. Only one year after completing an innovative restoration project, tests are showing “significant improvement” in the lake’s health – progress that DNREC says would have taken nature alone at least two decades to achieve.

EPA’s Mid-Atlantic Water Protection Division provided $73,800 in Section 319 funds for wetland restoration and other improvements as part of the project by Delaware to clean up and restore Mirror Lake – considered a gateway to the state capital.

Mirror Lake had been in decline for several decades due, in large part, to contaminants (PCBs, mercury and PAHs) in bottom sediments that are transferred to fish.

In the fall of 2013, contractors applied nearly 80 tons of an activated carbon product – the same technology used in many water filters – to bind contaminants in the lake’s sediments. Scientists did baseline testing immediately prior to the work and then went back a year later to test again.

They found a 60 percent reduction in the contaminants, “well on the way” to attaining the targeted decline of 70-90 percent within three to five years, according to DNREC.

Over that timeframe, the project is expected to result in the reduction or removal of the fish consumption advisory for Mirror Lake and the St. Jones River downstream to Court Street in Dover.

Check out this new DNREC YouTube video Exit for more on the project’s success so far.

The EPA funds were used to convert a sandbar into a landscaped wetland; supply stakes, native plants and trees; and protect the shoreline from erosion with artificial coir logs made of coconut husks and hulls wrapped in netting.

The Mirror Lake project is just a few miles downstream of the Silver Lake Park stream restoration project completed in 2012 with more than $200,000 in Section 319 funds.

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