The Gross Resevoir outside Boulder is a great place for people to go for some recreation just outside the city. People commonly drop in a paddleboard or kayak. I sadly don't have either, but I do have hiking boots and the hike from the nearby Forsythe Canyon Trail (moderate difficulty, one tricky section 3/4 of the way) which leaves from the parking lot area. It is a great 1 mile loop that ends at the north west side of the lake. I took a hammock with me and planted myself on one side of the lake's perimeter, overlooking a nice section of the resevoir.

Campsites are best accessed with a 4WD vehicle. There is a schematic map near the entrance to help you with the designated camping plots. This is also your last look at a bathroom - there are none located within the campgrounds. Bring in your own water as well.

If you're OK with primitive, this place has sites well dispersed for some privacy in off peak seasons. Since it is so close to Boulder, it is a common spot to see a lot of campers.