Welcome to the discussion forum Todd. As others have mentioned, depending on the type of experience you are looking for, fishing opportunities in the Lower Mainland in August is somewhat limited.
While salmon fishing on the Fraser River can be excellent. The amount of fishing pressure, in my opinion, does not represent how fishing in British Columbia really is. Unless you are on a guided boat, which you'll be doing for one day, you'd be lining up with many fishermen along the bank hoping to harvest a salmon or two. I'm sure you will enjoy the sturgeon/salmon charter trip if you are with an experienced local guide. My recommendation is to skip the shore fishing in that area all together because it would be more stressful than relaxing.
Here are some options that I recommend, based on my past fishing experience in August.
By mid August, the
Thompson River, which is a tributary of the Fraser River, should drop to reasonably low level for fishing. This river provides a resident rainbow trout fishery that fly anglers enjoy between July and September, but you can certainly try it out with the spincasting outfit. While our preference is to trick these fish with large dry flies in the evening hours, we also used to simply cast small spoons and spinners for them. In fact, they can be caught quite easily with this method. These trout are generally between 1 and 2lb, with the odd bigger ones. They fight very hard. The Thompson River runs from Kamloops to Lytton. The areas where I recommend for you to visit is upstream from Spences Bridge, where the flow is more moderate. It is doable for day trips, but ideally you should spend two to three days in this area because there's so much to experience. The drive from Lytton to Spences Bridge takes you along the raging part of the river where whitewater rafting is done. The areas for fishing further upstream is also great for swimming on those hot August days. In August, salmon will also be making their way up this river so you also have a chance to connect with a chinook or sockeye salmon. Openings for these species are usually announced in early August so keep an eye out for them if you decide to go up. For camping or accommodation in general, try not to stay near the river despite of its convenience. The trains run along the river, even at night, making sleep rather impossible. We learned our lesson many years ago.
If there isn't a preference in target species, then perhaps you should visit Steveston where I regularly spend my time in the summer. Check out the dock and see what the commercial boats are selling, enjoy the fish and chips, etc. Fishing in this area is available. You can target a variety of species that are not known for their table fare. You can spincast for northern pikeminnow, float fish with bait for peamouth chub, occasionally catch a flounder, you might even hook a cutthroat trout or bull trout. The two places where I like to spend my time at are
Garry Point Park and
No. 2 Road Pier. You need a tidal water fishing licence for this area.
Capilano River can be good in August, if we get a few rainy days. Last year we took advantage of a day of downpour by visiting the river when water level rose. Coho salmon moved into the river. While we could not land any salmon, we managed to hook a rare summer-run steelhead, which had to be released.
http://www.fishingwithrod.com/blog/2011/08/23/an-unexpected-lucky-catch/If Capilano River is low, then most coho salmon will be staging at the river mouth or in front of Ambleside Beach. This fishery can be done from shore, but you have to be there early in the morning to catch them. Locals have success by casting spinners and buzz bombs at these fish, which you can often see splashing on the surface. You need a tidal water licence for this area.
You should make a trip to the
Fraser Valley Trout Hatchery in Abbotsford. The visitor centre does tours of the hatchery as well as information session on freshwater fisheries around British Columbia. The facility also has two ponds filled with trout, which visitors can try catching during their visit.
The Skagit River is also another option for day trips. I'm not familiar with it so will let others to provide information on it.
I have a few other ideas, but will leave these with you for now to absorb.