Before dirt was moved at Chimney Hollow Reservoir in 2021, Northern Water implemented several environmental improvements nearby as part of our commitment to offset any environmental impacts of the new reservoir. A section of the Little Thompson River in Berthoud, and a second section north of Lyons, both decimated by the 2013 flood, received compensatory mitigation including the repair of natural channels and replanted vegetation. An area in west Loveland along the Big Thompson River, also impacted by the flood, had a diversion structure removed, the natural channel restored, and cottonwood and willow trees replanted. 

The Big Thompson Watershed Coalition, Windy Gap Firming Project participants, AloTerra Restoration Services, ERO Monitoring and the Northern Water Municipal Subdistrict identified sites, completed restoration at each, and began the monitoring and reporting phase which are required as part a permit granted under Section 404 of the Clean Water Act. Water resource projects that result in impacts to Waters of the United States, such as Chimney Hollow Reservoir, are required to obtain such a permit before altering or impacting a project site. While a steadfast objective of the Chimney Hollow Reservoir Project is to minimize environmental impacts, some are unavoidable. To compensate for this, Section 404 allows project participants to identify and enhance other areas in need of restoration.