UPDATE JUNE 2007:
The refuge has seen some changes since it was first opened and this cache originally set up. Several of the signs that were used as clues at the waypoints have been removed and one whole corner of the refuge has been closed, so it appears that waypoint 5 can no longer be reached. So, what I have done is put the answers to the missing waypoints in the hints; you can decrypt them as needed. Here are the original cache instructions:
It's not every day that over 2000 acres of new conservation land is opened to the public, but that's what happened October 23, 2005 when the Assabet River National Wildlife Refuge opened. Formerly the Fort Devens Sudbury Training Annex, the refuge encompasses 3.5 square miles in Hudson, Maynard, Stow and Sudbury. Find out more about the Assabet River National Wildlife Refuge at these web sites:
Friends of the Assabet River National Wildlife Refuge
Official Assabet River NWR web site
Trail Maps
However, as I understand it, national parks like this do not allow geocaches so this one is a puzzle cache with the actual cache box located just outside the NWR. To complete the cache you'll hike part of the refuge, mostly along one of the standard loop routes, and record some things that you see which will allow you to determine the final cache location. The loop is about 3 miles long, with a short section off the loop to a place I thought was interesting and that also offers a bit of a view.
The cache is a standard ammo box, which is quite appropriate if you know the history of the place, and includes finders buttons and some other odds and ends.
Instructions:
The posted coordinates are for the main parking lot and entrance to the refuge.
To find the cache you must find seven things along your route at the six waypoints listed. Each thing found will give you one of the missing digits in the coordinates of the final cache. If you visit the waypoints in order you'll do one of the standard recommended loops, plus a little spur off to visit something interesting.
The cache is located at:
42 2A.BC2
71 2D.EFG
Now visit each waypoint to fill in the missing digits.
Waypoint 1: 42 23.896 71 28.416 Find "G"
Look for a sign with "SG 1" on it; immediately below "SG 1" is a three digit number. Add the individual digits (i.e., if the number were "123" add 1+2+3 to get 6). Divide the result by 4. Put result in "G".
Waypoint 2: 42 24.185 71 28.873 Find "F"
Look for a sign with the distance back to the parking lot. The distance listed is "?.90". Read the missing digit and put it in "F".
Waypoint 3: 42 24.779 71 28.674 Find "D"
Look for a sign that says "SG 1?". Read the missing digit and put it in "D".
Waypoint 4: 42 24.575 71 29.196 Find "E"
Look for a sign that lists two distances. Add the two distances together and throw away the part to the right of the decimal point. The digit left is "E".
Waypoint 5: 42 24.789 71 29.080 Find "B"
Look for a warning sign. One line of the sign reads "...Act of 1950 50 USC 79?" Read the missing digit and put it in "B".
Waypoint 6: 42 24.062 71 28.911 Find "A" and "C"
When you are at this location you are at one of the numbered intersections on the official trail guide map. Which intersection are you at? Enter that number as "A".
Look for a green sign. How many letters are on the first line of the sign? Put that number in "C".