Improving Water Quality and Operational Efficiency at New Hampshire's Fish Hatcheries

Water bodies downstream of New Hampshire’s largest state-owned fish hatchery, Powder Mill State Fish Hatchery, were experiencing degradation due to excessive nutrient loading from the hatchery. As a result, the facility received an updated effluent discharge permit in 2022 with one of the lowest phosphorus limits in the country of 12 micrograms per liter, requiring a cut in production by 90%. 

In response, HDR was tasked to perform a statewide evaluation of New Hampshire’s hatchery system to recommend the best path forward to improving and modernizing state facilities to maximize funding and meet the state’s stocking goals. The study phase’s challenges included an aged system (average hatchery age of 88 years) built largely before modern regulations, historic funding opportunities requiring a fast-paced study and design schedule, and historically low permit limitations. 

As part of the study phase, we performed a pilot study at Power Mill Fish Hatchery and recommended reducing production at Powder Mill and constructing a new, state-of-the-art hatchery at the site of the existing New Hampton State Fish Hatchery. This proposal came after a year-long assessment to evaluate the feasibility and costs to achieve Environmental Protection Agency compliance and the conditions and capacities of all six New Hampshire Fish and Game hatcheries. 

The new facility’s construction at New Hampton is estimated to cost around $50 million and will be completed by the end of 2026. Efforts will also continue to improve the other facilities, including Powder Mill, working under a statewide plan. The renovations will feature increased efficiency in recirculating aquaculture systems. 

The New Hampton Fish Hatchery has historically produced an annual average of approximately 72,000 pounds of trout and Atlantic salmon, with a goal to increase production to 150,000 pounds. Treatment systems are being implemented to remove total phosphorus from the effluent to meet future EPA limits and to protect the receiving waterbodies. 

The project, which started in late 2024, is being delivered as a construction management at risk method and will support New Hampshire’s Statewide Production and Stocking Plan, thus maintaining angling opportunities and boosting the state’s economy while protecting natural resources.