Century Bog

Ecological Risk Assessment

Century Bog ERAPrinceton Hydro was hired by the Massachusetts Division of Ecological Restoration to design and implement a feasibility study for the restoration of a cranberry plantation in Plymouth County, MA. As part of our study, Princeton Hydro undertook an ecological risk assessment to determine whether decades of pesticide use had created unacceptable risks for wildlife under existing or proposed conditions.

We evaluated soil and sediment tests performed by others and concluded that historic pesticide residues, especially dieldrin and DDT, disproportionately occurred in a sand cap layer applied across the plantation surface to facilitate cranberry production.  We then designed and implemented a series of investigations to determine the aqueous mobility of historic pesticides, assess whether base-level food chain taxa showed evidence of pesticide in their tissue, and calculate dietary exposure to wildlife known to forage the site.

Our analyses indicated that low levels of the site’s food web did contain historic pesticides, particularly dieldrin. We also demonstrated that dieldrin could be mobilized from site soils. Our calculations of dietary exposure indicated that wildlife foraging at the site were unlikely to be exposed to dieldrin (or DDT) at levels that would lead to impairment. Our findings were integrated into our restoration design to reduce the mass of historic pesticide residue available in near-surface soils.

The investigation approach and data analyses methods Princeton Hydro used for this project are being implemented elsewhere within MADER’s portfolio of projects as a cost-effective means to address the practical fact of restoring and re-naturalizing lands that were subjected to persistent, environmental contaminants.