El Dorado County, California
Mosquito Rd -
Rock Creek Rd Loop
17 Mile Loop - Length
El Dorado- COUNTY
Single lane paved, 15% grade - PAVEMENT
180-degree hairpins - CURVES
Placerville - GAS
Quick Ride: Tight twisty single lane canyon ride over wooden suspension bridge
The Swinging Bridge
Twenty years ago, our realtor encouraged my wife and I to look at buying property in Swansboro. Originally known as Mosquito, this tiny mountain community at 2500 ft is anchored by the private Swansboro Airport. Swansboro is surprisingly close to Placerville, only five miles northeast of town center as the crow flies. Our contractor was even building a house there at the time and invited us to come see the house he was constructing which was bare framing at the time. We headed north 9 miles out of Placerville with our toddler in the back of our silver ’87 Oldsmobile and my wife quickly concluded that we would not be moving to Mosquito any time soon due to the single lane mountain road one has to traverse to reach the other side of the steep canyon involving multiple tight 180-degree switchbacks.
However, the perspective of the motorcyclist is quite different.
This ride is a loop road with Mosquito Rd as the southern leg, and Rock Creek Rd the northern leg back to Highway 193. As a description, we’re headed counter-clockwise up Mosquito Rd to Mosquito and back to Highway 193 on Rock Creek Rd. The vast majority of this loop is single lane twisty canyon goodness dropping down 1000 feet into the American Canyon and back out again, then following the canyon wall on Rock Creek Rd back to Highway 193. There are few guardrails if any and almost zero along the Rock Creek section.
Beginning of Mosquito Rd at original Placerville Train Station
Find Mosquito Rd in the heart of Placerville although you may want to pay attention to a map first to envision how to access Mosquito Rd. There is no off ramp from Highway 50 except the westbound lane. Eastbound on Highway 50 will require you to use the Broadway exit and make almost a full circle to head north onto Mosquito Rd.
Or… exit onto Main Street in Placerville, and ride east through town, Main Street becomes Mosquito Rd when it intersects with Broadway Rd. Ride under Highway 50 on Mosquito Rd past the present-day bus station, which was the original train station a century ago.
The El Dorado Trailhead also begins here atop the former railroad bed which has been converted to a hiking & biking trail. The bike trail parallels Highway 50 but only extends up to Camino, the center of the Apple Hill region in the Foothills.
This railroad bed once connected Old Folsom to Shingle Springs to Placerville to the (closed) lumber mill at Camino a century ago. The tracks have long-since been pulled up between Placerville and Camino but the tracks between Folsom and Placerville remain intact. Rumblings from the City of Folsom purchasing a train to provide Excursion Train Rides between Folsom and Shingle Springs keep surfacing but nothing is running as of yet.
Headed up Mosquito Rd, watch for the turn north 2.5 miles from Highway 50 as Mosquito Rd makes a 90 degree turn north toward the American Canyon. If you miss the turn, the road name changes to Union Ridge Rd to Carson Rd to North Canyon Rd to Larsen Dr to Cable Rd to Mace Rd which is the back entrance to the Apple Hill region surrounding Camino but a fun motorcycle ride to keep you off the busy Highway 50.
Mosquito Rd headed into the canyon near Quartz Hill Vineyard
Steep grades and very tight turns
There’s a large sign here warning no trucks with trailers, an 8-foot width limit and the 5-ton weight limit on the wooden bridge. Mosquito Rd is double yellow wide to the top of Union Ridge, then hooks right through a 20-mph corner beginning the descent into the canyon.
Beyond the Quartz Hill Vineyard, the double yellow drops away and it’s no center line from here becoming progressively narrower and plenty twisty. Perfect for motorcyclists, although note the steady surprise of local traffic and blind corners headed into the canyon. At the last 180-degree hairpin, a guard rail begins and you’ll get a quick glimpse of the wooden bridge.
The road is so narrow, there are several wide spots for autos to pull over to allow opposing traffic to pass by. Signs warn the auto traveling uphill has the right-of-way which could involve the downhill vehicle backing up to a wide enough spot in the road for both vehicles to pass each other. As you descend into the canyon, you can see autos coming down the opposing hill on the other side of the canyon wall.
Autos often stop on the downhill and wait on both sides of the river to take turns crossing over the wooden suspension bridge while still giving ample lead time, the closer you get to the bridge, the narrower the road gets and it’s best to wait a few hundred yards before the bridge within full view of any other auto on the other side of the canyon.
For locals, this a well-oiled dance and part of daily life of commuting to a remote mountain community.
Riding along the edge of Grant Lake
The Swinging Bridge
The original Mosquito Bridge was built in 1867 with the steel cabling constructed on site. The bridge was built before the time of the automobile and long before the weight of autos was considered in the design. Original photos show the 1867 bridge without any sides or railings. When automobiles became commonplace in the 1920s, the bridge would swing side to side from the added weight of autos thus gaining the moniker, The Swinging Bridge.
The present-day wooden suspension bridge was re-built in 1939 using the original 1867 foundation anchored by concrete pillars on either side and is 140 feet across and a mere 9-feet wide. Steel cables are suspended across the canyon with down cables attached to multiple intervals to support the weight of vehicles.
Mosquito Rd wasn’t paved until 1943 and the paving was laid over the top of the original wagon road. No apparent attempt to widen or smooth out the hairpins was ever attempted in 1943.
Vehicles must wait here to take turns crossing The Swinging Bridge
A washout a few years ago on the south side of the bridge was quickly repaired, and the pavement on the north side of the canyon wall is smoother with more recent repaving. Closer to Mosquito, the paving deteriorates.
Present estimates are about 1300 vehicles per day pass over the Mosquito Bridge although the accident rate on Mosquito Rd is 32% higher than other area roads.
The maintenance on the wooden bridge to make it safe for vehicular traffic results in annual maintenance that closes the bridge for several weeks at a time usually during summer. Additionally, the Mosquito Bridge has had major refurbishments in 1985, 1990 and again in 2011. El Dorado County estimates it was costing an average of $45,000 per year (a 10-year-old number) to maintain the bridge although recent estimates have bumped past $75,000 per year.
At 9-feet wide and limited to 5-tons, no emergency vehicles can traverse the bridge nor have the ability to negotiate the 180-degree hairpins on either side of the canyon. If you were to call an ambulance to Mosquito, despite being only a few miles from Placerville, it would take 45-minutes to reach you by having to use Rock Creek Rd.
The Mosquito Bridge is one of the last wooden bridges still in daily operation in the state and is slated to be replaced by a massive concrete structure 400 feet above the canyon spanning 650-feet ridge top to ridge top. After nearly 10 years of planning, construction is slated to begin in 2022 after many years of planning and several designs for bridges at different positions and various elevations have been proposed. The original road and wooden bridge will likely only be accessible as a foot or bike path. The Honeydew Bridge with its wooden deck on Mattole Rd is also slated to be replaced in the coming years as another example that comes to mind as these wooden bridges are quickly fading into memory.
As a single lane bridge, present day autos take turns and must wait to cross the bridge one at a time. The north side has a wee bit of space to park a motorcycle pointed uphill, but vehicles are often waiting here to cross the bridge one a time.
The south side of the river has two places to park a small vehicle. A space at the bridge on the south side and a hundred yards uphill from the bridge on the south end next to a small waterfall. In the 1960s, the rocks beneath the bridge were often known for naturalists enjoying the summer sun and it’s not uncommon to see vehicles parked in the hairpins with people walking down to the river in the canyon during summer.
Proposed all new Mosquito Bridge is due to begin construction in 2022.
The planned modern concrete bridge marks the end of an era where the term “wooden one-lane-suspension bridge” will soon be a lost term our children will read about only in history books. Plans for the new modern bridge across the American River Canyon have been in the planning stages since 2013. However, the Mosquito Bridge’s designation as a county historical landmark likely will save it from ever being dismantled or removed. We hope.
An electric power plant was built in 1889 a short distance downstream from the Mosquito Bridge at the base of Nelson Canyon and still exists today. (see below) The canyon was so steep, materials including a 7-foot Pelton water wheel were all lowered into the canyon with block and tackle. Telephone poles, the generator, and all heavy machinery had to be lowered into the canyon piece by piece via ropes and pullies.
Another power generating plant is directly below present-day Highway 193 & Rock Creek Rd creating Chili Bar Reservoir. The Rock Creek Power Plant provided the first electricity to area gold mines and Mosquito, several years before the Folsom Powerhouse was completed in 1895 a few hundred yards from Old Town Folsom and provided the first electricity to the City of Sacramento.
Another power plant known as Slab Creek was built a few miles upriver, and can be reached from North Canyon Rd outside Camino. The dam here is 250 feet high and 825 feet across while Slab Creek Reservoir is about 250 acres in size.
Aside from the single lane Mosquito Bridge, the only other bridge across the South Fork American River is Forebay Rd from Pollock Pines. At the end of Forebay Rd in the canyon is a small sandy beach along the north bank of the American River that few people know about. Forebay Rd continues (paved) to Brush Creek Reservoir.
The climb out of the American canyon on Mosquito Rd is steep and dramatic on the north side of the river pushing through four 180-degree hairpin switchbacks. The road is narrow and the sightlines in hairpins are nonexistent. It’s good practice to always be anticipating an opposing vehicle when you least expect one.
The climb is so steep, the hillside collapsed a few years back from heavy spring rains. The hillside was heavily fortified with concrete columns as CalTrans rebuilt the road cut. The narrow road however was left untouched. There’s one more hairpin half-way up the ridge at La Paz Rd, then the intersection with Mosquito Cutoff Rd, this is a shortcut back to Rock Creek Rd and the 122-acre Finnon Reservoir Recreation Area.
A few moments later Mosquito Rd emerges at the intersection with Rock Creek Rd at the airport runway. There’s a large picturesque white house here surrounded by vineyards known as the Alexander House at the corner. A small pond sits directly across the road from the Alexander House. It’s the perfect place for an afternoon stroll along the banks of the pond, and if you brought your lunch, there’s a single picnic table along the shore of the pond.
Swansboro Airport is home to about 25 planes
Mosquito Rd to Wentworth Springs
If you want a bit of dirt in your ride day, continue northeast on Mosquito Rd and the pavement ends as the ride reaches the national forest boundary.
The ruins of the 1920s Deer View Hotel are a short distance up Mosquito Rd but require some advance planning to know how to find the ruins. A grand hotel 4 stories with verandas around the building was completed but never opened after the owner died unexpectedly. Lack of attention quickly allowed the hotel to fall into disrepair and the building collapsed under subsequent snowfalls. Today only the foundation remains.
Numerous dirt roads spider off into the forest and Mosquito Rd can be a dusty ride over to Stumpy Meadows but is often used by dual-sport riders to reach Wentworth Springs Rd 12 miles north of Mosquito.
Mosquito Rd becomes dirt at the national forest boundary if you want to connect to Wentworth Spring s Rd
Sand Mountain Blvd
Worth mentioning Mosquito Rd has some expansive views of the Sierra Nevada range and it also intersects with Sand Mountain Blvd which is paved for the next 5.3 miles back to Quintette. This also means you’ll only need to stay on dirt fire roads riding northeast out of Mosquito for 6 miles before rejoining the pavement at Sand Mountain Blvd over to Quintette. Sand Mountain Blvd is a (paved) shortcut back to Wentworth Springs Rd and pops out at the Quintette Forest Service station on Wentworth Springs Rd. If you prefer the dirt, stay on Mosquito Rd and continue to Stumpy Meadows Reservoir. Eleven Pines Rd to Mosquito Ridge is right up the road. Continuing on Wentworth Springs Rd will allow you to reach Ice House Rd which is a can't-miss bucket list ride. Wrights Lake Rd and Forest Rd 71 to Silver Fork Rd to Mormon Emigrant Trail to North-South Rd to Highway 88 Carson Pass are more single-lane paved mountain roads no one has ever heard of.
Mosquito is credited with being the first 5000-acre subdivision laid out in El Dorado County dating to 1968, however, not in the image you’re picturing of grid pattern streets, cookie-cutter homes and cul-de-sacs. None of that ever materialized and it still hasn’t.
Plans were for custom homes on 2-acre lots along with several private lakes, numerous ponds and a private airport. Several streets were carved out of the forest to lay out the mountain subdivision that exists today spread out across about 7 square miles of forested land that borders national forestland on the north and east side. The American River Canyon borders the south side creating an isolated mountain oasis for forest living.
Franks Diner on Finnon Lake is the only business in town aside from a Real Estate office
The developer’s 1968 brochure to promote the new Swansboro Country subdivision read, "Deer stand and watch you pass, gray squirrels flick their bushy tails and chatter in concern. In springtime, dogwood and buckeye bloom and Scotch broom scatters its gold across the hillsides in breathtaking brilliance against the verdant green. In autumn, oaks and sycamores splash red and yellow through the forest, the madrone curves its tattered trunk between the towering fir and pine, and manzanita spreads a gray-green cover over the rich El Dorado earth. Through the multi-greens of summer or the snow-trimmed fields of winter, streams play their crystal way across the rocks, and waterfalls leap down seal-brown boulders or moss-covered ledges."
Originally comprised of logging camps, little gold was found in streams around Mosquito during the time when nearby Coloma lay at the center of the region’s 1850s Gold Rush and was only a few miles away to the west. Ditches left over from mining operations were re-purposed providing the needed water in the late 1800s for agricultural pursuits.
Finnon Reservoir was completed in 1905 originally constructed to power a sawmill and was much larger at 355 acres. The material for the dam was pulled from area hillsides with hydraulic mining equipment, ala Malakoff Diggins style, but the earthen dam was deemed seismically unsound in 1990 and it was recommended the 355-acre lake be drained. A compromise was reached when the Mosquito Volunteer Fire Association purchased the lake and its size was reduced to 50 acres. Original plans were to seismically retrofit the dam, but this will likely never happen due to the proposed cost of a seismic retrofit and the lake has remained at 50 acres. At Frank’s Diner, you can ride across the dam and circle around to the north side of the lake.
There are several small ponds throughout Swansboro Country besides Finnon Lake. There is a small campground on the north side of Finnon lake and the only business in town seems to be the real estate office, and Frank’s Diner on the south side of Finnon Reservoir you can plan as your breakfast or lunch stop.
A Civilian Conservation Camp was based in Mosquito prior to WWII and then housed conscientious objectors during WWII. A runway was originally carved out by the forest service and was then expanded in 1969 to allow realtors to bring in clients to show off properties. The private airstrip remains today as the present-day Swansboro Airport with several private homes along the runway. Commuters can land their planes and pull their airplane right into their home, hop out and walk into their dining room and sit down for evening dinner. Approximately 25 small aircraft are based here.
American River Canyon as seen from Rock Creek Rd
The airport can also serve as a base for fire attack aircraft. The King Fire in 2014 prompted this community of 400 homesteads to be evacuated. The King Fire, which started in nearby Pollock Pines, eventually burned 100,000 acres in a massive conflagration that was driven by high winds that thankfully pushed the wildfire away from Mosquito and into national forest land in the Crystal Range.
Rock Creek Rd
From Mosquito, head back to Highway 193 if you want to stay on pavement via Rock Creek Rd. Rock Creek is rather unique in the long list of California Motorcycle Roads, it rides along the edge of the American Canyon often with wide open views and steep drop offs. This type of road isn't for everybody and no, it’s not the Bolivian Death Road, but there are no center lines, no guard rails, and it’s a long way down.
On the other hand, we love motorcycle roads like this. Minor traffic, intense views, and an endless supply of curves will always be the motorcyclist’s first love. The road condition is actually better than the first leg of this loop on Mosquito Road. Less homesteads along the way assures fewer opposing vehicles. Daily traffic on Rock Creek Rd is only 25% of what’s on Mosquito Rd with most daily commuters and residents headed directly to Placerville via Mosquito Rd. On a weekend ride, you may see only a few other vehicles. Rock Creek is longer mile wise but you’ll enjoy the less opposing traffic.
Drink in the wide-open vistas along Rock Creek Rd while setting a relaxed pace that is consistent with road conditions and your skill level. Rock Creek can be bumpy, but backroads like this commonly are. Rock Creek Road flows back and forth high above the valley floor slowly descending in elevation. There may be fog on the valley below at certain times of year. On the flip side during summer, it can easily be triple digit temperatures on the hotter days.
For quite a few years, I rode right by Rock Creek Rd numerous times headed up to Georgetown and Wentworth Springs Road to get to Eleven Pines Rd or Ice House Rd. When I finally did ride the Rock Creek - Mosquito Loop, I kicked myself for my misguided years of spent youth, missing out on this extremely fun ride up to Mosquito.
The usual hazards to look out for such as the occasional pothole or more rarely, rocks. This is unusual although it does happen. Much more common in winter when heavy rains loosen the canyon walls. On one ride pictured here, several 12" diameter rocks lay in the road.
There may even be a waterfall pouring off the mountain side where Rock Creek Rd hooks into Nelson Canyon and the namesake of this ride, Rock Creek pours off the mountainside and continues into the canyon below under the curved Rock Creek Bridge built in 1936 by the Civilian Conservation Corps.
One-half mile east of the curved Rock Creek Bridge is a dirt side road denoted with a white post that reads Rock Creek Hydro (A smaller sign reads 10441 Rock Creek Rd) that heads down the edge of Nelson Canyon all the way to the bottom of the American Canyon. At the base of this canyon are the 1889 Rock Creek Power House and its successors, the 1907 American River Power House and the present-day Rock Creek Power House.
If you are headed downhill on Rock Creek Rd, this side road is easily missed as you zip by it, but when headed uphill and knowing where to look right after the arced concrete bridge over Rock Creek, this side road may pique your curiosity.
Rock Creek flows under the 1936 Rock Creek Bridge down Nelson Canyon
Saying to yourself, ‘I wonder where that goes’ is the cornerstone of your motorcycle riding experience. A short distance downhill is a gate, but park here and continue walking down the canyon as this is a day-use area. The river is a half-mile hike down the gravel road.
There’s a new powerhouse built in 1985 by Sithe Energies. The original powerhouse dating to 1889 was fed with water that flowed along the canyon wall on the north side of the river in the American River Flume, a combination of above ground flumes and in-ground ditches dug into the hillsides, then fed into two 30-inch diameter penstocks and descending 575 feet at high pressure to the powerhouse. The present-day powerhouse is rarely in use after court cases limited its activity to only certain months of the year when river flows are sufficient. Plan a trip here in early spring or even a sunny winter day when mountain snowmelt produces a more dramatic experience while the sounds of the rushing water in the canyon provide a stirring verbiage.
Another reminder about summer in this canyon producing triple digit temps and water flows are reduced to a trickle by autumn. At the end of the road is a wide flat open area and a picnic table to enjoy the rushing river water a few feet away. There are several historical episodes of ruins and foundations from past building projects
The uniqueness of Rock Creek Road & Mosquito Road as a loop lies in that these are some of the last paved roads in this part of the Sierra Nevada (between here and Lake Tahoe) as the elevation climbs. Interstate 50 borders to the south. Georgetown and Wentworth Springs Road is on the next finger to the north. Foresthill & Mosquito Ridge are on the next finger after that.
When these two roads are combined together, they amount to a mere 17 miles. Travel time is likely at least an hour due to low speeds and the number of times you stop to gape at the view that accompanies a ride like this.
Always on the lookout for rockfall on the road
Where to next?
Riding a counter-clockwise loop north to west allows Rock Creek Rd to pop out at Highway 193 in the canyon section. Super fun curves here headed uphill, but Highway 193 is often busy with daily commuters. If your desire is more backroads, head north up the hill on Highway 193 to Bayne Rd (easy to miss- It looks like a driveway). Bayne is a paved single lane back road (the map marks this as Kelsey) and likely one of the narrowest backroads for miles. It flows downhill to Coloma to Marshall Gold Discovery State Park, the origin story of the discovery of gold in California in 1848. The park is always worth a visit.
Another backroad worth mentioning is the Darling Ridge-Balderstone Rd loop. This easily passed over single lane paved mountain road back to Wentworth Springs Rd is reached a short distance away up Highway 193. Take Shoo Fly Rd or Spanish Flat Rd to Traverse Creek. These are single lane paved mountain roads. Speeds are slow and don’t ride these if you’re in a hurry. Better for the weekend explorer, but they are fun roads to explore and further your ‘I wonder where this goes’ mindset. Connect over to Darling Ridge and pop out at Balderstone Station along Wentworth Springs Rd. Ride Wentworth Springs Rd to Ice House Rd and back to Highway 50 for an all-day mountain loop
Darling Ridge Rd is a single lane paved road around the backside of Georgetown
Ride the Loop Clockwise
Clockwise riding into Placerville, there are fuel and eats, however, if that’s not immediately required, turn east on Union Ridge Rd and head into Apple Hill Country. Ride Union Ridge Rd to Carson Rd to North Canyon Rd to Larsen Dr to Cable Rd to Mace Rd which is the back entrance to the Apple Hill region surrounding Camino but a fun motorcycle ride to keep you off the busy Highway 50.
Placerville has all services and is the center of foothill living in El Dorado County. There are more super fun motorcycle roads surrounding this small town than you can spend multiple days of riding and still not ride them all.
Headed southward back into Placerville on Highway 193, ride into the canyon & back out. Highway 49 connects to Highway 50 at the south edge of Placerville. Head into town or head north of Highway 49 for more rides.
Ridden clockwise west to east from Placerville: Head north on Highway 49 and keep the speed low within the city limits. A short distance later, about a mile, Highway 193 falls off the ridgeline (east) down to the South Fork of the American River Canyon floor. As you start the twisty climb up the opposing wall, Rock Creek Road is half way up.
The Larsen Apple Farm has a massive water wheel worth checking out
Mosquito Rd - Rock Creek Rd - Photo Gallery
MORE INFO: Mosquito / Swansboro Country
RIDE (near) IT on a PASHNIT TOUR
17 Miles - LENGTH
Single lane paved - PAVEMENT
S-curves, 15% steep grades, 180 degree hairpins - CURVES
Placerville - GAS
Placerville - LODGING
2500 ft - PEAK ELEVATION
38°43′47″N 120°47′55″W - Mosquito / Swansboro
Mosquito History Part I
Mosquito - Rock Creek Loop