The Cape Cod towns of Brewster, Chatham, Harwich, and Orleans were jointly granted
MassDEP’s first watershed permit in 2018 to further nitrogen removal activities in Pleasant Bay,
the region’s largest estuary. To meet their individual responsibilities under the permit, the towns
have formulated nitrogen management plans that involve shellfish harvesting, permeable
reactive barriers, public sewers, golf course fertilizer controls and on-site denitrification systems.
The costs of these approaches vary widely, from less than $10 per pound of nitrogen removed
up to over $700 per pound.
With an EPA Southeast New England Program (SNEP) Grant, the Pleasant Bay Alliance looked
at ways to reduce watershed-wide costs through nitrogen credit trading. With this broad
approach, one town would remove more than its share of nitrogen using a lower-cost
technology, and a second town would scale back or avoid its use of a higher-cost system. The
savings would be shared by the two towns. In this study, three trading scenarios were identified
involving Brewster, Harwich, and Orleans. The sample trading scenarios included on-site
denitrification, sewers and permeable reactive barriers.
These hypothetical trades address the removal of 1,600 kg of annual nitrogen load or about
10% of the overall removals dictated by the Watershed Permit. Savings are projected to be
$670,000 per year, or a present worth of about $11 million, about 15% of the amount the towns
might otherwise spend on the more expensive technologies.
This presentation will describe the overall process of developing the nitrogen credit trading
Lead Presenter: Michael D. Giggey, PE, Senior Vice President, mike.giggey@wright-
Co-Presenter: Carole Ridley, Principal of Ridley & Associates, email@example.com,
Coordinator of Pleasant Bay Alliance