This reservoir provides 20% of the city's drinking water, and sure, hydration is important, but the real attraction here is recreation: 13 picnic sites, boat moorings and rentals, a snack stand, swim beach, restrooms, showers, sand volleyball courts, horseshoe pits, and a 5 mile ring trail are enjoyed by thousands of locals.
The many amenities accomodate nearly any sort of outdoor activity you could care to indulge in, and the refreshment of a swim is almost essential come the summer heat waves. Hordes of CU students gather here for bbq's and beach parties, so people watching is yet another pastime Boulder reservoir offers.
There is a small entrance fee $6.25 for adults. Occassionally after periods of high rain, bacteria-rich runoff causes the reservoir to close briefly.