Folsom Lake is a reservoir in Northern California formed by a dam built in 1955. It is a popular recreation area as there are many suburban areas on the south and west sides of the lake. The paved route around the lake is a popular choice for cyclists on the weekends as it has no steep grades and vehicular traffic is reasonable.
The route is a loop and could be completed in either direction and from any point along the route. The route as described is the shortest and simplest route possible on 100% paved surfaces. In the CCW direction starting in El Dorado Hills, CA at the intersection of Green Valley Rd and Francisco Dr, the route follows Green Valley Rd, takes a left on Salmon Falls Rd and follows that for about 12 miles down to the river, across, and back up. You must cross the bridge across the South Fork of the American River. You'll go back uphill into Pilot Hill where you will have to get to Highway 49 going north, either using a short section of Rattlesnake Bar Rd or Salmon Falls Cutoff Rd. There's a small general store here where you can replenish supplies. Heading north on Hwy 49 will take you through Cool and then down to the confluence of the Middle and North forks of the American River. A left turn keeps you on Hwy 49 which is also CA 193 and you'll face some traffic climbing up to the town of Auburn. In Auburn there are a couple route options but the most straightforward route follows High Street until you turn left onto Auburn-Folsom Rd which will be the last turn for about 15 miles as you pass through the towns of Loomis and Granite Bay. Using the shoulder of Auburn-Folsom Rd sees a lot of bicycle traffic but is wide enough to share. There is an alternate route using the Jedidiah Smith Memorial Trail and a couple levees that starts a quarter of a mile south of the Eureka Rd intersection. The next turn is a left onto Folsom Lake Crossing, unless you took the bike trail which will put you on the side of the same road but requires taking a right at a fork as you see the long hill up to the dam ahead of you. The two alternate routes converge here as you climb up to the lake. Be sure not to cross the bike trail bridge over the road at the top of the hill because you need to continue along what will now be E Natoma St (previously Folsom Lake Crossing). Another alternate route option comes into play by taking a left off E Natoma St onto Mountain Village Dr (which takes you to Folsom Point Boat Ramp). That option follows a dirt levee that will spit you out a mile or two later onto Green Valley Rd near Sophia Parkway. The original route just stays on E Natoma St then turns left onto Green Valley Rd but you will deal with more possible stops and traffic. Continue on Green Valley Rd back to where you started and you're done!