Sparse, crowded hard-to-get-to camping
Note: This campground is only accessible via 4x4 vehicles. Do not attempt in your sedan or lower SUV.
Bigger note: The map to this campground is wrong. Follow the directions, not the map.
The camping sites are sparsely shaded and well used- we found a lot of trash at our site. Each campsite is equipped with a fire pit, picnic table, and room for 2-3 tents. There is no water, trash, or toilets.
We got there around 9pm on a Friday (not the brightest idea) and could not find any open spots, off the road or in the campground. We camped in a field behind the parking lot for the night, and were told in the morning by a (very nice!) ranger that camping anywhere but the designated spots carries a minimum $300 fine, so we moved to a newly vacated spot. If you are going to camp at an undesignated spot, be sure to leave by 8am or earlier so as to not get yourself fined.
There are only 6 camping spots easily accessible from the parking area, along with ~4 more down by the water (about a 1/2 mile walk), and ~6 along the road. These all fill up quickly after 5pm thanks to their closeness to Boulder.
The recreation at Gross Reservoir, accessible via beach about ~1/2 mile walking from the parking lot, is delightful. You do not need a boat permit - just a life jacket on board (1 for each person). No swimming is allowed in the reservoir and there is often a ranger on the lake ensuring everyone is following that rule.
Pro Tips:
If you are late to the campsite and absolutely need to find somewhere to camp (do not start a fire, even in "rocked-in pits" that have been used before), try:
West of campsite 24 (there's a ridge with 2 primitive campsites or the field)
North of campsite 24 (there's a field)
Between campsite 24 & 25 (there's a field)
Just South of the south parking fence (there's a field)