From the lower trailhead, run down the gated-off dirt road to the left. You'll see signs for Chavez Trail. You'll run through the Chief Hosa campground. Follow the road and signs 0.25 miles to the singletrack trail.
Once on the singletrack, you'll run along a shaded hillside. After about 1.5 miles, you'll start running alongside the creek. You'll make a few crossings back and forth. These crossings can be a bit tricky if the water level is high so bring an extra pair of socks just in case you get your feet wet.
The Chavez Trail eventually intersects with the Beaver Brook Trail