• Bon Tempe Lake (map)
  • Fairfax, CA, 94930
  • United States

2024 Nav-X GPS MAP TREK #5 @ Mt. tamalpais WATERSHED

Quick Info

  • Date: Tuesday, 1 October to Saturday, 30 November

  • Location: Mt. Tamalpais Watershed, Fairfax, CA

  • Courses: 2h & 4h GPS Map Trek

  • Price: $12 (2h) & $17 (4h)

  • Map Handout: Saturday, Nov. 2 at 10am


INTRODUCTION

  • We have set up a course with 48 checkpoints on a new map in the Mt. Tamalpais Watershed / Bon Tempe Lake area near Fairfax, CA. Get as many checkpoints as you can in either 2 or 4 hours.

  • There is construction in the park on weekdays we recommend running the course on a weekend (more info below).

  • Our suggested race time is Saturday, November 2 at 10am. We will have a Nav-X team member there to hand out pre-printed maps (no extra charge) if you register by October 31. Since this is not an official event, there will be no signage so just meet the Nav-X staff member at the start triangle (Bon Tempe Lake dam parking lot). Map handout will be from 9:30-10:30am.

  • We will be using a Smartphone app named “MapRun” to record your visit to each checkpoint based on your GPS position. You can also use your Garmin watch running the MapRunG app.

  • All the instructions including directions to the Start are below. Be safe and have fun!



EVENT INFORMATION

  • MAPRUN - Please see this page for instructions on how to use the MapRun smartphone app. It’s important that you load the course while you still have Internet service. Search for “2024 Nav -X GPS Map Trek Mt. Tamalpais” and pick the right course (2 hr or 4 hr). Or you can click one of the links provided above to load the course.

  • DIRECTIONS TO START: The start/finish is located closest to this parking spot. (The start/finish is just far enough from the parking area so that you don’t accidentally trigger it when you park). Follow highway 101 north or south to exit 452, downtown San Rafael. Follow 3rd St west, which becomes 2nd St, then 4th St, then Red Hill Ave. After 2.2 miles from the freeway, turn right onto Sir Francis Drake Blvd. After 1.7 miles, turn left on to Pacheco St and then an immediate right onto Broadway and then immediate left onto Bolinas Rd. Follow for 1.5 miles, and then turn left onto Sky Oaks Rd at the sign for Lake Lagunitas. After 0.5 miles, stop at the parking area on the right for the payment machines.

  • PARKING - Costs $8 at the machines just past the park entrance and ranger buildings. The automated machines take credit cards or cash. Put the parking permit on your dashboard and continue on Sky Oaks Rd for 0.3 miles and bear right onto Bon Tempe Rd. (dirt). Continue 0.4 miles to the parking lot at Bon Tempe dam. The parking here can be full on weekend afternoons so it’s best to arrive early.

  • CONSTRUCTION PROJECT: There is a construction project taking place on weekdays until the end of 2024. The road to the start (Bon Tempe Road) is closed during construction times and parts of the course may not be able to be reached, in particular the Azalea Hill area in the west. One of the days of course setting was a weekday and there was no construction going on. However, you can’t count on that so if you have to do the course on a weekday and the road to the start is truly closed, you can park along Sky Oaks Road and walk ~1.3 km (0.8 mi) to the start/finish along the Sunnyside trail on the north side of Bon Tempe lake. Here is the place I would recommend parking for this option. You should probably also plan a route that does not follow Bon Tempe road but rather just crosses it.

  • BATHROOMS - There is a portapotty just off the parking lot near the start but no water. There are also bathrooms and water fountains at the Lake Lagunitas parking lot at the end of Sky Oaks Road (paved).

  • GEAR RECOMMENDATION - We recommend participants bring the following:

    • Smartphone - goes without saying since we are using an app for timing

    • Compass

    • Long pants or at least gaiters for the tall grass, brush, and poison oak

    • Snacks & Water, especially if you are on the 4-hr course

    • Whistle for safety

  • TRASH - While on the course, practice Leave No Trace (LNT) - bring all trash back to the parking area.

  • BE DISCREET - We don’t have a permit so try not to be too noticeable when entering or exiting off-trail areas.


MAP & COURSE NOTES

  • VENUE - The Mt. Tamalpais Watershed area is one of the most beautiful in the Bay Area, consisting of stunning redwood forests and lakes. The mapped area includes the existing BAOC Bon Tempe orienteering map in the north and east, newly mapped Rocky Ridge in the south, and newly mapped Azalea Hill in the west.

  • PROHIBITED AREAS: Residences, maintenance yards, golf course, etc. Observe the restricted areas (hashed purple lines on map). In particular, the top of Azalea Hill and the creek between Azalea Hill and Bon Tempe Road are prohibited.

  • TERRAIN - Mostly forested with some open grassland and manzanita areas. Redwood trees are fairly abundant in the area. The top of Rocky Ridge and Azalea Hills have an extensive area of open land with manzanita bushes of varying height. These bushes are mostly mapped as dark green (fight) but in fact, you can usually find passages through it. If you get stuck in a dead end, generally you can back out and find a clearer path through nearby. The yellow color in these areas is not grassland like the rest of the map, but rather shorter manzanita bushes which despite having great visibility is still tough to get through.

  • MAP - The full map was created in Aug and Sept 2024. It has 5 meter contours, vegetation density (3 shades of green), cliffs, and water features based on high quality LIDAR data from 2018-2019. BAOC’s Bon Tempe orienteering map (2015) is incorporated into the overall map. Roads, trails, fences, and other features were added using Google aerial imagery, Strava Global heatmap, and the adventure racing map used for the Bone Tempest events. Other features were added and adjusted during field checking but the map lacks most orienteering-level detail such as boulders, knolls, rootstocks, single trees, etc.. (except of course for the area covered by the BAOC orienteering map). On the orienteering map, stands of redwood trees are shown with a solid thin black line, rather than the dotted veg boundary symbol so that they are more legible. The narrow ride symbol is used to denote an old road grade. These are often overgrown with no trail but are still useful for navigation. Also note that the autogenerated vegetation density from the Lidar data iin the newly mapped areas are shown by somewhat different colors than the corresponding areas in the existing orienteering map. The autoveg color for rough open land is a darker yellow and the greens are tinted yellow compared to the greens of the orienteering map. Unfortunately, I can’t edit the colors of the auto vegetation.

  • COURSE - The course was designed by Heidi Cusworth and the checkpoints were visited by Bill Cusworth. There are 48 checkpoints varying in point value from 30 to 100 points. The approximate straight-line distance to get them all is about 18 km. Generally, higher value checkpoints are farther from the start, harder to find, or some combination of both.

  • START - The start area is shown on your map as a triangle and is on a trail just east of the parking lot. Do not approach the start until you are ready to go! Your GPS device will start you automatically and alert you by beeping once you are within ~15 meters of the spot.

  • SCORING: Just like our other events, each checkpoint has a point value reflecting the difficulty (higher point value for tougher checkpoints). The point value is the “10 part” of the checkpoint code. Examples: 33 = 30 points, 50 = 50 points, 88 = 80 points, etc. Late penalty is 10 points per minute or any part of a minute (1:01 late = -20 pts)

  • MARKERS - All checkpoints are marked with biodegradable ORANGE flagging with “Nav-X” written on it. Be aware though that as time goes by, animals and hikers may remove some of the flagging, so it is not guaranteed to be present. The start/finish does not have flagging because it is in a public place.

  • FINISH - the finish is marked on your map with a double circle and is located at the same place as the start. When you are within ~15 meters of the spot, your GPS device will register a finish. Do not approach the finish until you are ready to end your course. (Depending on the device, it may be possible to continue the course after this, for example if you approached the finish spot by accident. However, this might not work for you, so we recommend you don’t go near the finish until you are done.) Remember to upload your result after you finish (if it doesn’t happen automatically).

  • MAP PRINTING - You will need to print your own maps (unless you show up on the day of the preprinted map handout, Nov. 2). We are providing a Zip file with the map documents in PDF format. The text checkpoint descriptions are on the map.The Zip package contains 3 files: the course map at 1:16,000 scale (8.5 x11, 1 page), the course map at 1:10,000 scale (8.5 x11, 4 pages), and separate symbolic & text checkpoint descriptions.

  • If you want to report any problems with the course, please email info@navxchallenge.com.


REGISTRATION


IMPORTANT SAFETY NOTES

  • YOU ARE DOING THIS AT YOUR OWN RISK - WE TAKE NO RESPONSIBILITY FOR ANY INJURIES OR DEATH. HAZARDS INCLUDE STEEP HILLS, LOOSE ROCKS, CLIFFS, OCCASIONAL DENSE AND SHARP BRUSH, POISON OAK AND TICKS.

  • CELL COVERAGE - Unfortunately, there is very little cell phone coverage in most locations on the map. I was only able to get a signal on Rocky Ridge, the ridge south of Bon Tempe Lake.

  • WHISTLE - Due to the self-serve format, you may be completely on your own when you run your course. Be aware of this! You should bring a whistle in case of an emergency.

  • WATER - There is no water available at the start/finish and but there are water taps at the Lake Lagunitas parking lot (at the end of the paved road). The creeks are fairly dry in Autumn. It is recommended to bring all the water you need on the course with you.

  • POISON OAK - not as bad as other maps in the Bay Area but I did get a rash while course setting.

  • TICKS - are present and were seen during course setting.




Thanks for reading, and have fun! - Bill & Heidi and the Nav-X team