Don Castro is two different places in the summer and winter. In the summer, there is an active swimming lagoon with places to picnic and lay in the sun. In the winter, they close and drain the lagoon, and the activity focuses on the nearby San Lorenzo Creek Reservoir. This little lake is stocked with fish, and I saw a happy fisherman with three healthy rainbow trout in his catch of the day.
The pier offers views of the little lake and a great place to fish from or just watch the birds. Doubling back, I returned to the road and headed west to the start of the Whispering Creek Trail. This trail covers the south side of the lake, and starts out just after you cross over the dam. You'll see the trail marker on the left.
Follow this trail through a tangle of giant Eucalyptus trees that hug the shore.
On the ground you'll see a lot of Eucalyptus debris, ivy, small shrubs and grasses. Up on the hills, there are some neighboring houses with great views of the lake.
Keep hugging the shore, and look out over the lake to see some of the residents. These ducks were just having a Sunday morning chat when I snapped this picture:
Whispering Creek Trail eventually leads you past marshy section of the reservoir, where the Eucs mostly disappear and you'll see more native trees, including a few Bays, Oaks and even the occassional Redwood.
You'll get to a point where the Whispering Creek Trail splits, and you can either keep to your left, hugging the shore, or wander up through more dense woods. I kept to my left. Eventually the trail intersects with the Chabot to Garin Regional Trail. If you keep to your left on this hike, you'll find your way back to where you started. The trails to your right lead to Five Canyons Open Space and Cull Canyon Recreation area. I kept to my left and followed the Ridgetop Trail. The canopy opens up here, and I saw some bees polinating some nearby foliage.
Eventually, you'll find your way back in to a canopied section of the trail. On your left is more marsh, and the trees are covered in climbing ivy.
Past this section you'll be able to see where the ducks hang out. The were darting in and out of the reeds and diving for breakfast.
Continuing on the trail, you'll start to see more Eucs, especially this giant cluster not far from the Swim Lagoon.
At the end of the trail, I saw Mama Blue Heron. There was a nest on the other side of the lake, and this delicate beauty was grabbing twigs to strengthen it.
You'll end up at the swim lagoon, where there is a bathroom and plenty of picnic tables. This is a short and easy hike, but offers a lot to see and experience.