Constructed in 1913, the DAM is a 140FOOTLONG concrete structure consisting of a spillway, a set ofgated outlets at the right abutment, and a fish ladder at the left abutment

After years of discussion andevaluating alternatives, the town now plans to remove the DAM as the best way to improve fish habitat, remediate water quality issues, and address flooding and safety concerns. The proposed project wouldinvolve eliminating the entire existing DAM structure, including the fish ladder, while leaving theabutments in place. IT would also entail reshaping the river channel by removing accumulated sedimentto ensure a stable streambed and conditions favorable to upstream fish passage. The proposed projectwould also include design, permitting, and construction of upstream fish passage at the oyster reservoirdam.project goals and objectives:goal 1: advance restoration efforts for diadromous fish populations by eliminating a barrier toupstream fish passage. The oyster river provides habitat for nine fish species of concern listed in newhampshires wildlife action plan, including ecologically important native diadromous fish species: theanadromous blueback herring (alosa aestivalis), rainbow smelt (osmerus mordax), and alewife (a.pseudoharengus), and the catadromous american EEL (anguilla rostrata). DAM removal would createapproximately 1.8 miles of freeflowing habitat along the oyster river mainstem from head of tide tothe oyster reservoir DAM, and restore as much as 3.4 river miles of tributaries to a freeflowingcondition. As a result, diadromous fish species would be able to successfully ascend the exposedrestoration reach, supporting a selfsustaining fish run. Improving fish passage at the upstream oysterreservoir DAM would be accomplished by installing a new fishway (no upstream passage is currentlypresent) in collaboration with the NH fish and game department and others. A fishway at this damwould open another 12.6 river miles on the oyster river mainstem, and almost 22 river miles ofperennial tributaries, including caldwell, chelsey, and dube brooks.goal 2: improve the oyster rivers declining water quality and strengthen the oyster rivers naturalecosystem. Listed as impaired for low dissolved oxygen and PH for aquatic life related in part tostagnant water conditions in mill pond, the oyster river is included on new hampshires section 303(d)priority list of impaired water bodies. Returning the mill pond DAM impoundment to a freeflowing statewould dramatically improve the rivers aquatic environment. There would be a substantial net benefiton fishery resources in this reach of the oyster river and hamel brook andby extensionthe greatbay estuary and the gulf of maine.goal 3: increase the oyster rivers flood resilience and reduce durhams vulnerability to the growingrisk of coastal storms. Modeling conducted in a 2020 feasibility study showed that removal of the millpond DAM would increase the oyster rivers flood resilience in all of the flow conditions analyzed. Damremoval would also help alleviate flooding of adjacent properties.