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Bon Tempe Reservoir

Greg Ehrensing Memorial Volunteer Event

Date: Nov. 23 - 24, 2019
Location: Fairfax, CA
Event Director: - 415.456.8118
Course Setter: Johanna Merriss
Type: C; Greg Ehrensing Memorial Volunteer Event; LIMITED ATTENDANCE; RESERVATIONS REQUIRED

Please note that fees and time limits apply. Events are typically not canceled due to bad weather.


, Event Director

This annual event is being held in honor of the BAOC volunteers who have worked hard and used their skills to create orienteering experiences for all of us. The event is open (and free) for all who have (or will have) volunteered to help at BAOC events in 2019. It's not too late to help out at one of the remaining events and still qualify for Bon Tempe!

We use this event to remember Greg Ehrensing, a dedicated BAOC volunteer, who particularly enjoyed this event in his "backyard". Greg directed and course set this event several times, as well as always helping out with whatever was needed even when he wasn't on the crew that day.

The event will take place over two days, Saturday & Sunday, November 23th & 24th. The courses will be the same both days, so just plan on coming out on either Saturday or Sunday.

The Bon Tempe Reservoir is a beautiful orienteering area located on the slopes of Mount Tamalpais near Fairfax in Marin County. Bon Tempe consists of some of the finest terrain in California for orienteering: redwood covered hillsides, open grassy slopes, runnable mixed forest, and extremely low poison oak. The rangers have cleared a lot of underbrush from the hillsides, turning a lot of the map from light green to white (runnable).

As stated above, this event is free to all participants. Well, okay, there is an expense​—​there is a park day-use fee of $8.00 per car collected at the entry kiosk. This kiosk is staffed sometimes, but usually not, so you will most likely need to use their "automated pay station" that accepts debit and credit cards, and cash up to $10 bills (but it does not return change!). That machine is about 150 meters beyond the kiosk, on the right side of the road.

BAOC is a great, all-volunteer organization. Thank you all for making it succeed.

Reservations Required

The land owner, the Marin Municipal Water District limits how many participants we can have each day, which is the main reason we hold this event over two days. So, as usual, advanced reservations will be required, and will be accepted on a first-come first-served basis. Please do not show up at the park without a reservation. You will not be allowed to compete.

As of Nov. 18th, there are only two spaces available on Saturday and two on Sunday.

To reserve a spot, email with the information listed below. He will send you a confirmation. Also, he will post to the BayONet ( if and when the daily quotas are filled. If you miss registering on time, he will put you on a waitlist in case of cancellations.

  1. Your name
  2. Your preference for Saturday, November 23, or Sunday, November 24
  3. Your course preference: See the course information below

Note: Scott will give preference on Sunday to people who tell him they are willing to help with control pick up. 🙂

If you are already registered, you may modify your race day or course before the event as long as there is space available. But we want to get a good idea of how many maps to print.

Again, you must be preregistered to attend this event. If you just show up without registering, you will not be allowed to run a course.

Schedule For Both Days

 10:00 AM – 12:30 PM: Starts open
           2:00 PM: Courses close


As in past years, there will be only three courses: Brown, Green, and Red, all of advanced difficulty.

Here are the course statistics:

    Course   Distance   Climb  Controls  Water Stops
    Brown     3.3 km    149 m     11          1  
    Green     4.7 km    220 m     14          1
    Red       6.1 km    285 m     17          2

There will be a 500-meter walk from the registration/parking area to the Start. The Finish is at the registration area.

All the courses cross roads that have light traffic. Be careful crossing!

Be sure to read the Course Setter's Notes for more information.

Check-In and Start Procedures

We will have a remote Start, which is a 500 m walk along a flat road. It takes less than 10 minutes.

Upon arriving at Registration:

  1. Check-in your E-stick.
  2. Walk to the Start.
  3. Agree on a start order with anyone else who is at the Start. Keep a two-minute (or more) interval between starts on each course.
  4. CLEAR & CHECK your E-stick.
  5. At your selected start time, punch START.
  6. Look at the map and go!

Event Volunteers Needed

Although this will be a "bare-bones" event, we will still need the following volunteers:

Driving Directions

The approximate coordinates for the event are 37.9485,-122.5974.

The first challenge of the event is to locate it! Due to MMWD rules, no directional signs will be posted. There are several ways to get to Bon Tempe from Highway 101 in Marin. the default route is listed here:

From Highway 101 in Greenbrae, take the Sir Francis Drake Blvd exit, and go west for 5.5 miles to the town of Fairfax. Turn left at Claus Dr (Rino gas station on the right), and then immediately take another left onto Broadway. Turn right at the next corner, which is Bolinas Rd.

Stay on Bolinas Rd for 1.5 miles. Turn left at the large, brown, wooden sign with white lettering that says "Lake Lagunitas". Stay on this road until you reach the ranger kiosk. Pay the entrance fee ($8 per car) at the entry kiosk or pay-and-display machine (see comments above).

Proceed on the paved road to the parking lot at the very end. (Do not turn right onto the gravel road to Bon Tempe Dam.)

There's a map here that shows the location of the event.