I think the cowlitz river (at least near blue creek) is in lewis county..... but the cowlitz does join with the columbia at longview which is in cowlitz county.......... current is pretty strong near the longview ramp, but if you can manuever across the river here you gain access to the mouth of the coweeman and this small river doesn't run as fast as the cowlitz this time of year and it's easy to paddle upstream trolling whatever you want to troll... there's supposed to be steelhead and coho and stuff in the coweeman, but to be honest the only thing I've ever caught there was a few small squawfish.. (oops I guess we're supposed to call them northern pikeminnows now)
trolling in a canoe is something I can relate to WAID...
A large shallow, year round lake named "Silver" is located in Cowlitz county and they plant trout that can be caught by trolling... good ramp and access along the northeast shore of the lake... waves can be treacherous for canoes here on windy days though.... From the public ramp I would head to the right and out into the main lake to troll for trout....
Kress lake is also year round and located in cowlitz county... it is well stocked and small enough to feel comfortable on using a canoe... if you are a strong paddler it might seem too small but I've trolled it in my canoe and there always seems to be a few willing 9 to 10 inch rainbows or brown trout swimming around.... Last time I trolled it I think I was using the fly rod and small black woolly buggers..
there's also a good "flyfishing only" or selective fishery lake east of woodland called "Merrill Lake"..........
you have to gain some altitude to get there and the road may be covered with snow right now and there is a gate about 100 yards or more from the shoreline.. so if you can make it to the access you will have to carry or drag the canoe for a bit but this lake is a good one...
there are also a couple of big reservoirs (Yale and Merwin) that are open year round... most don't think of them as "winter lakes" because the focus of most sporties there is "kokanee" and kokanee tend to be spring and summer biters... however they also contain cutthroat and bull trout and these can be caught during winter months... but the bull trout must be released.. they are protected.....................
there's a U shaped lake in woodland that may be open year round (check the regs on this one because I can't recall the seasons there)... it gets planted with lots of trout and stuff and is about the right size for trolling in a canoe....
another option might be "sacajawea" which is in the city limits of Longview and which receives regular stocking so the local kids will be entertained.... Will have to drag the canoe 40 or 50 yards over the grass to get to the water but it's a fun lake to paddle around in and there are lots of fish to be caught....
If you drive west of longiew on the "ocean highway" you will pass a boat ramp on the left just before driving along the coal creek slough...
probably a few trout and/or steelhead here but check regs on what can be fished and what can be retained.. I can't recall all the details there....
if you turn south just before the slough you will pass more sloughs on the right and I've seen canoes in the water there but it looks like a bit of a hassle to drag the canoe down over the grassy dike slopes.. not sure if these waters are planted or what's in them either......
driving further west on the ocean highway you will get to cathlamet (which is in wakiakum county as I recall.. but very close to cowlitz county).. there's a ramp here and if you turn right instead of left after you leave the boat harbor you enter a series of sloughs that intersect with the mouth of the elochoman river which has a good steelhead run... read regs carefully though if you choose this option because I have never fished it.. just been in the area and logged it in my head as a place to hit someday...
also if you travel slightly south of cowlitz county into clark county you can take a right at the "ridgefield" exit and work your way down to the ridgefield boat access... this access is on what's called "lake river" which is just a long narrow slough connecting vancouver lake with the columbia river...... never fished this one either but if you put in at the ridgefield access and go left instead of right you have lots of protected water to troll... there are supposedly trout, catfish, panfish, bass, and lots of different species residing in these shallow waters but I've never made this trip either...