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Abstract: Session F  1:30 pm (Back to Session F)
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Small Pond, Big Hazard – Mitigating Dam Removal with Stream Restoration

Joe Arrowsmith
Mike Blose
Straughan Environmental, Inc.
Columbia, MD

Authors: Joe Arrowsmith, PE, Mike Blose, PE

Thousands of small ponds are currently maintained within the Bay watershed. In Maryland, these ponds are regulated by the state under code 378. The Maryland Dam Safety Program has made updating the risk classification of many small ponds a high priority. Municipal pond owners are finding that previously unclassified ponds may be classified as a high hazard. This classification is reserved for dams that upon failure would result in potential loss of life and property. Owners must consider whether the risk and cost of a high hazard asset is worth the benefit it provides.

In this presentation, we will provide an overview of the role of 378 ponds and offer commentary on when it’s time to consider removal. We’ll demonstrate two-dimensional modeling techniques to help understand the hydrology of dam failure. We will also evaluate stream restoration as a design technique to offset changes in hydrology as a result of small pond removal. We’ll provide project-based examples in which we calculate the impact of stream restoration on downstream hydrology. Finally, we will evaluate water quality and habitat tradeoffs associated with maintaining or decommissioning a pond and compare them to those against functional uplift from stream restoration.