• Warren Richardson Trail (map)
  • 6201 Channel Dr
  • Santa Rosa, CA, 95409
  • United States

2025 Nav-X GPS MAP TREK #4 @ Annadel State Park

Quick Info

  • Date: 2025, Thursday, May 1 to Monday, June 28

  • Location: Trione-Annadel State Park

  • Courses: 2hr & 4hr GPS Map Trek

  • Prices: $17 (2h) & $22 (4h); Juniors 50% off, Club members $2 off; also see below for new pre-printed map options.

  • Suggested Race Time: Sunday, June 8 at 10am


INTRODUCTION

  • The 4th event in the 2025 NAV-X Challenge brings us to beautiful Trione-Annadel State Park, located in eastern Santa Rosa.

  • ~45 checkpoints are marked on a Lidar-updated orienteering map of the park and you have 2 or 4 hours to try and get to as many checkpoints as you can.

  • The competitive window for this event is May 1 - June 30. Results during this time period will be included in the official results and accrue Nav-X Challenge series points but the course will still be available on MapRun until Jan 1, 2026 after which it will be placed in the archive for club member access. 

  • New this year: we are offering pre-printed maps for $10. Maps will be mailed to you within 5 days and should arrive in your mailbox within 7 days total. For Annadel, you need to order your map (1:10000 scale) by May 30.

  • Our suggested race time is Sunday, June 8 at 10am. We will have a Nav-X team member there to hand out pre-printed maps (1:10,000 scale) and control descriptions, if you register for this option ($6) by June 2.  Since this is not an official event, there will be no signage so just meet the Nav-X staff member at the start triangle (Annadel SP parking area in Santa Rosa, CA). The maps will be available from 9:30am - 10:30am.

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

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.

  • WATER - There are no open water spigots at the start/finish. The creeks are mostly wet and there is a small lake in the middle of the map. I recommend bringing all the water you need with you.

  • TICKS - Ticks are present in the winter/spring months. Check your body and clothing regularly.

  • Mountain Biking is very popular in Annadel so watch out for bikes moving at high speed. The riders are mostly very considerate.


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 “2025 Nav-X GPS Map Trek Annadel” and pick the right course - 2hr or 4hr. Or you can click one of the links provided above to load the course.

  • DIRECTIONS TO PARKING: The parking area is located here. From highway 101 in Santa Rosa, take exit 488B to merge onto CA-12 E toward Sonoma.  After 1.7mi, keep following CA-12 by turning left onto Farmer’s Lane. After 0.8 miles, turn right onto Montgomery Drive and follow for 2.7 miles. Turn right onto Channel Drive a follow for 1.1 miles to the Trione-Annadel SP Ranger station on your right. 

  • PARKING  - Park in the small lot and pay for a parking pass ($10) before continuing about one mile down to the end of Channel Drive to the Warren Richardson trail parking lot. This parking lot is lightly used and has amenities.

  • BATHROOMS - There are portapotties at the th south end of the parking lot and a water fountain and faucet just off the NW end of the lot in a picnic area in the woods.

  • 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 and brushy vegetation

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

  • TRASH - There are garbage cans near the parking area.  Practice LNT (Leave No Trace).

  • PETS - Pets are not allowed in the park.

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

MAP & COURSE NOTES

  • VENUE - Annadel is a very interesting venue and generally considered one of the best in the Bay Area. While it is steep in places, it’s less steep overall than most Bay Area venues but does contain quite a bit more rocks than other local venues. Annadel has a variety of terrain. It’s predominantly oak forest with tall grass but also contains open meadows, conifer forests, stands of redwoods and manzanita patches. What makes Annadel unique is that the area once contained many cobblestone quarries so there are left over features from the quarry activity such as pits, depressions, knolls, cliffs, and rock fields. In October 2017, the eastern ⅔ of the park, which covers the eastern section of the course map, was burned in the Nuns fire. Since then, the burned areas have been overgrown with dense grass, berry vines, and poison oak. In September 2020, the Glass fire burned the northern part of the park just south of the Cobblestone trailhead.

  • PROHIBITED AREAS: Residences, maintenance yards, etc. Observe the restricted areas (hashed purple lines on map).

  • MAP - The map was made using LiDAR data from 2013. From this data, very accurate 5 meter contours were derived. Automated vegetation data was also obtained from Lidar (more on this below). A new vegetation layer was generated in 2023 to give a cleaner, simpler look and new contours were generated at the same time. Roads and trails were imported from Open Street Map, Strava heatmap, and augmented with personal GPS tracks. Aerial imagery was used to trace fences, water features, roads, and trails. Point and line features were then imported from the old BAOC map using a long and complicated process (called Rubbersheeting).

  • MAP VEGETATION: The automated vegetation from the Lidar data is very good at showing dense forest due to low tree branches. Almost all of the dark green on the map is thick manzanita and it mapped very accurately. Undergrowth does not show up as well and does reduce runnability of the white forests a bit. In particular, the parts of the area that were burned in the 2017 Nuns fire have grown up significantly since the Lidar data was collected in 2013. This applies to the eastern half of the course and the SW ridge line, but the worst area is definitely the SE quadrant of the course. In these areas, there are some berry vines mixed with significant ankle to knee-high poison oak patches. You can mostly step around the poison oak but I attempted to show the areas that were particularly bad with the vertical green line “undergrowth” symbol overlaid on top of the auto vegetation. This undergrowth mapping is very approximate but should give you a good idea about what parts of the map to stay out of.

  • OTHER MAP NOTES: Since the trails in the forests are mapped with GPS data, they are smoothed out and don’t show all the small twists and turns. I tried hard to make sure the intersections looked right. Mountain bikers are creating new trails all the time. The mapping of rock detail came from the old BAOC map which was first made in 1989. As such, the mapping of these features is a little outdated and not completely consistent with current symbols.

  • COURSE - The course was designed by Heidi Cusworth and the checkpoints were visited by Bill Cusworth.

  • MARKERS - All checkpoints have been streamered with orange flagging tape. Streamers sometimes get removed by humans or get chewed by animals - so if MapRun beeps at a checkpoint but you see no streamer, don't worry - just carry on.  Conversely, if you get to a streamer and MapRun does not beep, you can get it fixed by following the steps in the instruction document. The start/finish does not have flagging because it is in a public place.

  • START - The Start is shown on your map as a triangle and is on the gate at the start of Warren Richardson “trail” - actually a dirt road - and far enough from the parking area so that you don’t accidentally trigger it when you park. Do not approach the Start until you are ready to go! MapRun will start you automatically and alert you by beeping once you are within ~15 meters of the Start. 

  • 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 Finish, MapRun will register a finish. Do not approach the Finish until you are ready to end your course. Remember also to upload your result after you finish (if it doesn’t happen automatically).

  • 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, 70 = 70 points, 115 = 110 points, etc. The late penalty is 10 pts/minute.

  • MAP PRINTING - We are providing a Zip file with the map documents in PDF format within 24 hrs of registration. The text checkpoint descriptions are on the map. You will need to print your own maps or choose one of the 2 pre-printed map options. For $10, you can have a map mailed to your address (allow 7 days for maps to arrive); this option is available until May 30 on the registration page. For $6, you can pick up a map at the in-person meetup on June 8 from 9:30am-10:30am; this option is available until June 2.

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


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