The expanded dam will cause increased mercury levels in Gross Reservoir that are expected to necessitate severe fish consumption advisories and impact our ability to fish in the reservoir.

For at least 7 years of construction, the South Shore recreation area will be closed to recreational activities such as canoeing, SUPing, kayaking, and fishing, while also heavily restricting hiking and cycling access.

Dam construction uses heavy explosives to create aggregate, causing loud blasting noise in surrounding areas. This will be audible to nearby residences for multiple years of construction.

Denver Water estimates that in order to expand Gross Reservoir and Dam it will need to clear cut over 200,000 trees from around the reservoir.

Denver Water predicts this project will require 98+ trips per day for logging trucks, dump trucks, and other heavy equipment along small mountain roads like Flagstaff Road, Gross Dam Road, and Coal Creek Canyon (Hwy 72).

The project will disturb and destroy wetlands and habitats for elk, bear, mountain lions, raptors, and countless other species of animals and insects that live in and around Boulder, Gilpin, and Jefferson Counties.

The project’s estimated cost in 2006 was $148 million; now, it is expected to cost anywhere from $380 to $450 million, or even more. Project planners aren't sure of what the final cost will be or who will pay for it.

Expanding the dam will mean the destruction of a beautiful area, threatening wildlife, woodlands, and recreation; it will also leach heavy metals into the water table and South Boulder Creek.

Denver Water estimates that in order to mix concrete for the expanded Gross Dam they will need to transport 55,700 tons of highly toxic coal fly ash from a location 350 miles away in Wyoming. This fly ash will be stored in the shores of the reservoir in a high wind corridor.