First off, please just talk about this particular topic, I'm not interested in any other locations for this type of fishing just insight on this particular one and I'm really trying to find helpful information. VAbasser and I are trying to plan a day to make this hike through the woods of hemlock park in PWC off of yates ford rd. it's up bull run from bull run marina above the occoquan, I've ridden over it on a train (VRE) many of times and really want to fish it especially in the heat of summer, it's seems prime for smallmouth and largemouth. Just any advice on the hike itself, where to park, snakes, water depth etc. is very much appreciated. We'll probably be wading I'm assuming so it may just be spinning gear but let me know what you think equipment wise also, if you've done this. My other idea was parking at the Manassas park VRE and walking the tracks, here's the area... the first one is the zoomed out version and the second is zoomed in on the bridge area i want to hike to...

I haven't but there are photos out there of people that have done the hike starting at the route 28 bridge down to bull run.  

where are said photos?

I've been to Hemlock Overlook once and hiked down to the water. That part isn't very far at all, but I didn't go upstream very far. When I was there, the water was too high to fish, but it seemed like a good place. Lots of timber from what I remember, and pretty good shoreline access to the water. There are trail maps at Hemlock Park that you might be able to use to find some trails that are useful.

I've wanted to fish up there by that bridge after seeing it on google maps, and you're right, it does look like a good smallie area. Let me know how it goes.

That is very helpful dan, thanks for the information!  If all goes well I'll be doing this more and more hopefully, I'll let ya know if you want to join in.