Letter: Groups not downplaying impact of Conowingo

A recent news story and several letters in the Carroll County Times have discussed Commissioner Richard Rothschild's assertion that the federal government and environmental groups are conspiring to downplay the role of sediment coming through the Conowingo Dam in polluting the Chesapeake Bay, in favor of blaming farmers for the damaging runoff. These claims are anything but accurate.

The U.S. Geological Survey is addressing the contributions of the Conowingo reservoir and dam to Bay pollution. In 2012, we published a report on increasing sediment and phosphorus pollution coming past the dam and into the Bay. In a report published in January, the USGS and research partners documented how the dam has become less effective at holding back pollution through time.


We have also addressed other pollution sources. In 2015, the USGS released a report, "Understanding Nutrients in the Chesapeake Bay Watershed and Implications for Management and Restoration – the Eastern Shore." The authors reviewed more than 130 articles containing the best scientific information, and found manure and fertilizers laden with excess nitrogen and phosphorus were the main causes of degraded water quality on the Eastern Shore.

Much ado has been made about a satellite image of the Chesapeake Bay watershed used in the 2015 report. A USGS graphic artist used a Sept. 13, 2011 satellite image of the Bay to help orient readers. The image showed a large sediment plume caused by Tropical Storm Lee's heavy rainfall. To make the Bay and its tributaries easier to see, the artist digitally removed the plume. While this was an unfortunate artistic decision, it had no bearing on the scientific findings in the peer-reviewed report.

About six months ago, when we realized there were concerns this image may have misrepresented the science, we revised the report to replace the altered image with the original photo.

Unfortunately, the early use of the altered image continues to distract some from scientific information that can help guide Chesapeake Bay restoration.

We encourage the public to go to and read the Eastern Shore report. It is an accurate, useful summation of the science about nutrients from Eastern Shore waterways and their contribution to the Chesapeake Bay watershed. The USGS stands behind its findings.

Dan Hippe

Reston, Va.

The writer is deputy director of USGS Northeast Region.