Decided to tack on this hike after a morning of paddling the lake, to make the long drive from Seattle a bit more worthwhile. This was my second time at Diablo, parking at the Colonial Creek Campground to use the boat launch there. Was not nearly as busy as the previous time (late June), there was parking (not ample, but available) the whole time I was there from 8:30-2:30. I will say traffic was heavy leaving the park in the afternoon, and the drive back took a full 45 minutes longer than the drive in, so keep that in mind if you're trying to make it back to the city by a certain time.
Started up at 12:30, reached the top about 1:15, rested and snacked for about 20 mins, and was back to my car a little after 2:00. I went at a moderately fast pace, stopping to take pics. The start of the trail is rocky (large gravel) and hard to find at first, but once you cross the bridge leaving the campsites the trail is easy to follow from there, and mostly dirt with few rocks/obstacles. Plenty of places to stop and rest on the way, up as well. Trail is mostly OPEN and not shaded so it was a hot one, definitely don't forget sunscreen. It's not too steep or long, though, so that was a benefit given the temps. Not very busy either, which was nice. I passed other hiking groups once every 10 minutes, max. Some flies and other bugs, but not as many as expected. Bug spray still recommended if bugs tend to like you.
Certainly recommend if you want a short, not too strenuous hike in the area with GREAT views. The view of the lake isn't as good as the main Diablo Lake trail but they are still worthwhile given the trail is half as long, and the views of all the surrounding peaks are excellent, at multiple points both up and down.
Final random note--I stopped to splash my face and head at the end, to rinse off sweat/sunscreen/bug spray and to cool down in the stream right as you re-enter the campground. Once my hair dried in the car, it was so unbelievably soft. I don't know what's in that water, but ladies (and guys) I recommend sticking your head in it ;)

Comments
Forestdancr on Thunder Knob
Thank you for the report! I'm going to be there next week and dreading the heat, so good to be prepared with the knowledge of little shade.
One comment though: Please rinse off bug spray, if you must use it, by carrying water away from the stream and letting it drain into someplace without plants or insects--such as the parking lot. Think of the poor critters downstream!
For what it's worth, I am VERY sensitive to bug bites, but I learned 30 years ago that even the most potent DEET only works for about 10 minutes when the bugs are really bad--and citronella oil is just as effective and non-toxic. I rarely even use that, opting for covering up when swarmed and tolerating a few welts when the bugs are only "an annoyance." Plus, I've learned to resent them less since learning that the males pollinate all those beautiful flowers we enjoy!
Posted by:
Forestdancr on Aug 10, 2018 01:25 PM
Jenn27549 on Thunder Knob
If my comment wasn't clear, I splashed water from the stream onto my face and head used my own towel to wipe my face and hair--I wasn't bathing or dunking myself into the water.
Posted by:
JennJK57 on Aug 10, 2018 01:31 PM
Jenn27549 on Thunder Knob
Additionally, people with severe allergies don't always have the luxury to "tolerate" bites, as they can make one very ill later.
Posted by:
JennJK57 on Aug 10, 2018 01:33 PM
Forestdancr on Thunder Knob
Yes, I am well aware of that, as I'm a medical professional and I've also been that person, though my sensitivity is not as severe as it used to be. But that's why I always have long sleeves, long pants, a hat & head net along during bug season. I only meant to share my experience, not to prescribe it for others. :)
Posted by:
Forestdancr on Aug 10, 2018 01:51 PM
Forestdancr on Thunder Knob
Thank you; good to know! The critters thank you too!
Posted by:
Forestdancr on Aug 10, 2018 01:47 PM