Table of contents

Bon Tempe Reservoir

Greg Ehrensing Memorial Volunteer Event

Date: Dec. 5 - 6, 2020
Location: Fairfax, CA
Event Director: - 415.456.8118
Course Setter: Dennis Wildfogel

Photo gallery image (click to enlarge)

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

December 7th Update  

Complete information about how to run the courses after the event are available here.

December 3rd Update

I hope everyone who has signed up is ready for some great orienteering this weekend! Everything you need to know about the event is already posted below, so I'll just say here that I will be around the E-punch table both days, and will be able to answer any and all questions you might have. The three most important things to keep in mind are:
      1. Wear a mask.
      2. Maintain physical distancing.
      3. Have fun!
 Scott Aster, Event Director

Great news to report! We are now good to go for holding the first official BAOC event since the COVID-19 virus forced us to suspend events back in March!

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).

Unfortunately, due to COVID-19 restrictions, the usual feast of holiday food has been canceled, but join us Sunday evening on Zoom to socialize and talk over the courses. Please let BAOC President know you'd like to attend, and she will send you the session link privately.

Note: We use this event to remember Greg Ehrensing, a dedicated BAOC member, 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.

Registration Is Closed


We are restricted by our permit to 28 people each day, with morning and afternoon sessions of 14 people each. This event will provide a good opportunity for us to try out different COVID-19 procedures to see which work well, and how to ramp up to a future event where the public is invited.

Note: It will be possible to run the courses before or after the scheduled event days. See below for more information.

Important Highlights

Here are the most important things for all entrants to know:

  1. You must read and abide by the COVID-19 instructions.
  2. You must use an SI AIR+ E-stick in touchless mode. If you don't have one, we will lend you one.
  3. All the courses have a map exchange.
  4. The map used by the courses has undergone considerable revision. There are details in the Course Setter’s Map Notes that you'll want to know about.

COVID-19 Instructions

Note: These instructions were modified on 12/1 at 10:00 AM, and might be modified again before the event. Please come back here the day before you run to check for changes, and to make sure you’ve read the latest Course Setter’s Notes.

In order to keep everyone safe, healthy, and stress free, please follow these instructions for the Bon Tempe event:

Location in the Park

Note: We will not be using the picnic shelter as in the past. Instead, will be set up next to the parking lot for E-punch as well as the very nearby Starts. Directions to the event are below.


There will be three advanced-level courses, with the same courses used both days. As you can see in the course details below, there are lots of controls. 🙂

Here are the final course details:

    Course    Length       Climb       Controls
    Brown     3.7 km     85 m (2.4%)      30  
    Green     5.1 km    165 m (3.3%)      36
    Red       7.0 km    280 m (4.0%)      44


How To Use SI AIR+ at Bon Tempe

No one will be allowed to "punch" controls unless they use an SI AIR+ E-stick. If you don’t have your own SI AIR+ E-stick, we will lend you one for this event. Scott will have disinfected the loaner sticks and laid them out on the table, so you can pick one up without touching the others.

Put the stick on your finger as usual. If you wear a GPS watch, it’s best to put the SI AIR+ on your other hand to avoid interference.

Clear and check by inserting it as you do with a conventional stick. The CHECK unit turns the stick on, so it's important that you do that.

When you're ready to start, insert the stick into the START unit (but do not touch the unit). (We have the unit set this way so that picking up your map close to the START unit doesn’t accidentally start the clock on your run. Be aware that the setup might be different at other events.)

When you reach a control point, pass the stick within 18 inches of the unit. The stick will flash and emit a series of beeps when it registers a punch.

The flash and beeps are powered by an internal battery. The batteries last for years, and battery checks will have been done, so don’t worry about the battery running out.

Passing the stick near the FINISH unit records your finish and turns your stick off.

To download after your run, insert the stick into the download unit as usual. If you have a loaner E-stick, leave it on the table​—​Jay does not want the finger strap back, so please remove it and keep it ("Happy Holidays" 🙂).

Note: If you use a loaner E-stick, be mindful that you are responsible for not losing it! (They cost about $80!!)

If you want to know more about the technology, you can read this PDF (365KB) or look at the SPORTident website (

Map Exchange

All the courses have a map exchange. That is, there are two separate maps, one with the first part of the course and one with the rest of the course. The control where the map exchange takes place is on both the first and second maps. Ordinarily, you drop off the first map at the exchange control and pick up the map for the second part. But due to the pandemic, we will use instead a “map flip”: both maps will be in the map case you receive at the Start, back to back, so that the Part 1 map shows out of one side of the map case and the Part 2 map shows out of the other. Clue sheets for each part are printed on the appropriate map. A loose clue sheet will also be in the map case, on the Part 2 side. The clue sheet is folded so that you see only the clues for Part 1. Maps for each course will be in a box near the Start, with the Part 2 maps facing upwards. Right before you start, you will have the opportunity to remove the loose clue sheet from your map case and do with it what you will (e.g., place it in a clue-sheet holder). More details about that are in the Start Procedure section below.

When there is a “real” map exchange, you don’t have the second map until you reach the map-exchange control, and you don’t have the first map after you leave the map-exchange control. So, on your honor, for these Bon Tempe courses you should not look at the second map until you actually punch in at the map-exchange control, and after that you should not look at the first map again. Similarly, please leave your clue sheet folded and place it in your holder so that you initially see only the clues for Part 1. At the map-exchange control, you can flip the clue sheet so that you see only the clues for Part 2.

Pandemic note: The maps and loose clue sheets were arranged in their map cases on Sunday, November 29, nearly a week before the event, and haven’t been touched since.

Event Schedule & Logistics

Here are the times for the four start windows:

Saturday: 10–11 AM and 1–2 PM
Sunday: 9–10 AM and 12–1 PM

All participants have been assigned a start time during one of those one-hour periods.


Please get yourself near the assembly area early, but don’t be in the assembly area until you need to be. Read on.

Bon Tempe can get crowded on sunny weekend days. That can cause delays entering the park and might mean having to park up the road from the Lake Lagunitas parking area. Give yourself plenty of time to get there so that you’re not late for your start. On the other hand, it is important that we don’t have people congregating in the Registration/Download/Start/Finish area, so please don’t stay in that area unless you are picking up your loaner SI AIR+ E-stick, checking in at the download area, or until ten minutes prior to your start time.

Bon Tempe Assembly Area Click the image for a slightly larger copy

It is of course okay to use the portapotties that are near the Start at any time. If you’ve gotten to the Assembly Area early, you can walk around the Warm Up area (see the Assembly Area map at the right), or even better, walk five minutes up to Lake Lagunitas, the lovely mountain lake at the south end of the Assembly Area map. There are several benches and meadows on the east side of that lake, not far from the dam, if you just want to hang out; if you are so inclined, it’s an additional 1.6-mile walk (30–35 minutes) around the lake. Visiting Lake Lagunitas is also a delightful thing to do after your run.


Note that you must purchase a parking pass ($8) when you enter the park. If the entrance booth is not staffed (unlikely), then you must stop at the automated machines that are a tenth of mile further down the road. See information below for more details.

If the Lake Lagunitas parking area is full (unlikely but conceivable if you are arriving midday and the weather is good), you can park in the huge overflow lot that is about 220 m (3-minute walk) north of the Lake Lagunitas parking area. The entrance to that lot is on the east side of Sky Oaks Road, just south of where the road makes a sharp bend (and where Filter Plant Road heads off to the north). You will want to park as close to the entrance of that lot as you can; the rest of that lot consists of red clay that kicks up and covers your car.

If you choose to drive into the small lot where the registration table is set up, note that there is a one-way traffic flow through that lot: enter through the southern portal, exit through the northern one.

Wear A Mask

You are expected to wear a mask from the moment you leave your car after arrival until the moment you get back in your car to leave. The only exception is when you are out on the course. Even then, you should have a bandana or mask around your neck and pull it up over your mouth and nose any time you get near another orienteer or any other park visitors.

We truly hope that none of you sees this as a controversial requirement. It is of course for the protection of others as well as for your own benefit. We don’t know what it’s like where you live, but at Bon Tempe it is common practice for people to wear masks, and for runners to have a mask around their neck that they pull up when getting near others.

By following that practice you will also benefit BAOC: at this writing, Bon Tempe is the only orienteering venue where we can get a permit, and we sure don’t want to upset the rangers by having some park visitors complain “Some guy with a maniacal look and a map in his hand came barreling out of the woods and almost ran me over​—​and wasn’t even wearing a mask!”

Please see more about this here.

Before You Run

You need to get your E-stick registered at the Download station. Go to that station about 20 minutes before your start time. Give anyone who is already at Download plenty of room. If you are getting an SI AIR+ loaner, this is when you pick it up.

Start Procedure

Two or three minutes before your start time, check with the event official who is monitoring the download station (probably Scott) to make sure it is indeed your turn to start. (Ten or fifteen minutes earlier, you should have visited the download station to register your E-stick on the computer [and pick up your SI AIR+ stick if you are getting a loaner].) Then proceed to the CLEAR and CHECK units in the Start area, which will be in sight very nearby. (No event officials will be present in the Start area, nor anyone else for that matter.) Boxes containing the maps and clue sheets will be adjacent to the CLEAR and CHECK units.

Please be sure to read the notes above about the courses having a map exchange prior to reading the rest of this Start Procedure section.

SI AIR+ sticks will not operate in touchless mode unless they are first inserted in a CHECK unit, so don’t forget this step. (The sticks can still operate by physically inserting them in a control unit, but that’s what we’re trying to avoid.) After inserting your stick in the CLEAR and CHECK units (without touching the units), carefully pick up the top map case in the box for your course. At this point you should remove the loose clue sheet and put it in your clue-sheet holder or whatever. Try hard not to look at the Part 2 map that’s facing you.

When you’re ready, move the few steps over to the START unit and insert your SI AIR+ in that unit (again, without touching the unit). The unit and your stick will beep​—​you can then flip over your map case to see the Part 1 map and begin your course.

During Your Run

Remember to be mindful of any other people you encounter​—​mask up!

At each control, simply wave your SI AIR+ over the unit a few inches away​—​do not touch the control unit. The stick will flash and beep to confirm recording the control.

After you punch a control, immediately move at least 5 meters away before planning your next route, to give other incoming orienteers room to punch. For virtually every leg, a good strategy is to start off going straight towards the next control, so there’s no need to linger after you punch.

Remember that you must not look at the Part 2 map before reaching the map-exchange control, and you must not look at the Part 1 map after leaving the map-exchange control (i.e., as described above).

When You Finish Your Run

After you “punch” the FINISH (just wave your SI AIR+ over it), immediately move at least five meters away even if you feel like collapsing. Catch your breath and get your mask on before going to the Download station.

We would all like to see our friends and discuss our courses at this point, but please don’t do that in the Start/Finish/Download area. And if you do it anywhere, you must have masks on and maintain social distance from one another. Finally, since our permit requires that we have only fourteen people out there at a time, please leave the area as soon as possible, and no later than half an hour, after you finish. Note that on Sunday evening there will be an online Zoom session where we can discuss the courses.

Assigned Start Times

The assigned start times for the event are below. This is a COVID-19 prevention regulation that we will use now and in future events until restrictions are lifted or greatly relaxed.

You may contact people in your session to switch times with them if you choose, but no one will be allowed to start after the end of each session’s time period. There are also a couple of empty time slots in each session. Contact if you want to change to one of those.

Please pardon any misspellings below!

For the record, a few requested changes were made below on Nov. 24 at 4:45 PM.

Saturday AM Session – Starts between 10 AM and 11 AM

     9:56   Erin Schirm
    10:00   Vic Revenko
    10:04   Joan Roos
    10:08   Penny DeMoss
    10:12   George Minarik
    10:16   Leslie Minarik
    10:20   Open to registrants who wish to switch
    10:24   Graham Brew
    10:28   Owen Fennern
    10:32   Michael Behrens
    10:36   Shura Kretchetov
    10:40   Open to registrants who wish to switch 
    10:44   Rex Winterbottom
    10:48   François Léonard
    10:52   Marie-Josée Parayre
    10:56   Wayne Staats
    11:00   Open to registrants who wish to switch

Saturday PM Session – Starts between 1 PM and 2 PM

     1:00   Sarah Williams
     1:04   Nancy Lindeman
     1:08   Rita Wong/Ashwin Vaidyanathan
     1:12   John Crowther
     1:16   Marina Keating
     1:20   Amy Winston
     1:24   Brooke Staats
     1:28   Chuck Spalding
     1:32   Tac Sugiyama
     1:36   Gavin Wyatt-Mair
     1:40   Fyodor Konkov
     1:44   Jeff Goodwin
     1:48   Aron Walker
     1:52   Julia Doubson
     1:56   Open to registrants who wish to switch
     2:00   Open to registrants who wish to switch

Sunday AM Session – Starts between 9 AM and 10 AM

     8:56   Deron van Hoff
     9:00   Jennifer Kerr
     9:04   Rosemary Johnson
     9:08   Jay Hann
     9:12   Gary Kraght
     9:16   Olga Kraght
     9:20   Gary Carpenter
     9:24   Vicki Woolworth
     9:28   Open to registrants who wish to switch
     9:32   John Richardson
     9:36   Theo Verhoeven
     9:40   Tom De Vre
     9:44   Johanna Merriss
     9:48   Open to registrants who wish to switch
     9:52   Kyle Halliday
     9:56   Jitka Hiscox
    10:00   Evan Custer

Sunday PM Session – Starts between 12 noon and 1 PM

    12:00   Dwight Freund
    12:04   Jeff Lanam
    12:08   Misha Kreslavsky
    12:12   Greg Favor
    12:16   Werner Haag
    12:20   Paul Perez
    12:24   Peter Hsia
    12:28   Dennis Wilkinson
    12:32   Stephanie Maclean
    12:36   Derek Maclean
    12:40   Quincy Rosenzweig
    12:44   Eric Rosenzweig
    12:48   Johanna Karras
    12:52   Tapio Karras
    12:56   Open to registrants who wish to switch
     1:00   Open to registrants who wish to switch

Running Before/After Event

Since registration for the Dec. 5/6 event was full, we are providing some alternatives for people who would like to go out on one of the courses but couldn't be there for the event itself (or if you were at the event and want to run another course).

Each control used at Bon Tempe is marked with a small surveyor flag with the control number on it. Here are some options for running a course after the event (detailed information is available here).

  1. We've left those surveyor flags out there after the event was over. The course maps are available for download here, so you can go run a course "Corona style."
  2. Bill Cusworth has set the courses up on MapRun ( This is an app that you run on your smartphone, and optionally on a Garmin GPS watch. The app knows where the controls are, and when you get to one it will beep and record your split. And when you get to the Finish, it will upload your route and splits to RouteGadget. So, all you need to do is print yourself the appropriate course map (see #1 above), upload the course data to your smartphone (and optionally your Garmin watch), get yourself a smartphone holder that you strap to yourself (or use a Garmin GPS watch instead), and you're ready to go. Complete details on this option are available here.

Driving Directions

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

The approximate coordinates for the event are 37.9497,-122.5974. Use those coordinates, use Google Maps to get directions to "Lake Lagunitas Parking Lot", or take the default route described below.

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 (coffee shop on the corner) onto Bolinas Rd.

Stay on Bolinas Rd for 1.5 miles. Turn left at the large, brown, wooden sign on your left with white lettering that says "Lake Lagunitas", "Alpine Lake", and "Bon Tempe Lake".

News flash: A street sign has been put up for the road into the park, at the intersection where the wooden "Lake Lagunitas" sign is. The road you want to turn onto is named "Sky Oaks Rd". So, after driving 1.5 miles up Bolinas Rd, you will turn left onto Sky Oaks Rd at that sign (it's above the STOP sign for the approaching traffic), and follow that road to the entrance kiosk and then to the parking lot.

Stay on this road until you reach the ranger kiosk. If the kiosk is not staffed, pay the $8 entrance fee at the pay-and-display machine 150 m further on the right. The automated pay station accepts debit and credit cards and $1, $5, and $10 bills, but it does not make change.

Proceed on the paved road to the parking lot at the very end, following any signs to Lake Lagunitas. (Note: Do not turn right onto the gravel road to Bon Tempe Dam.)