It's a well-defined trail, from the entrance to the gravel pit, but just to be sure, I've listed a trailhead waypoint. A few hundred meters further, you'll come to the Alouette River where travelers will get wet feet if they go any further. But if you insist, there's a road that leads to the east side of Alouette Lake just beyond the river crossing. Horse riders frequently make use of this fording place.
The cache is not quite as far south as the river. You'll see the imposing object that holds it just west of the trail.