Gross Dam Road is a dirt road with some significant twists & turns, however Denver Water Board believe it to be passable to two wheel drive cars. Gross Dam Road is being opened to Coal Creek Canyon residents to ease the commute burden on some Canyonites, but it is not being opened to recreation.
Drivers need to be additionally careful since repairs to washouts at Gross Dam mean Denver Water Board have additional equipment and trucks in the area.
As a comparison for those new to this road: Gross Dam Road is far more rutted/dusty/steep/windy/narrow/rough than Gap Road. Denver Water Board typically do a very good job of maintaining it, however they have not been able to smooth it since the rains of the flood (instead they focused on getting it open.) Expect it to be rough.
Additionally recognize that this narrow dirt road is likely to be seeing a lot more traffic on it than usual. Road conditions could worsen with use (as they have on Gap Road) and remember that some parts of Gross Dam Road are already in poor shape. Up here (closer to Coal Creek Canyon) at approximately 1400 Gross Dam Road there is a repaired (but not completely repaired) wash out. Do not expect soft verges on the edges of the dirt road to be as stable as normal, and do not allow your vehicle to sink into these soft edges.
If you chose to drive Gross Dam Road please be careful, and stay safe.