Folsom Lake has plenty of water heading into the fall. As of Wednesday morning, the reservoir is at 73% of capacity. That is the highest the water level has been in early September since 2019. … At this point in the year, the reservoir is drawn down as managers send water to local customers and provide for environmental needs. At the same time, a notable amount of water is lost to the dry air sitting just above it through evaporation. … Last month, evaporation accounted for 6,500 acre-feet of water loss at the lake, a rate of about 100 cubic feet per second. Lessard said that compared to the size of Folsom, which can hold more than 900,000 acre-feet, that loss is relatively small.