I fish the bypass all the time.... skeeters, I never seen no skeeters up there, LOL.. actually, it does have a lot of damn mosquitoes, all the irrigation ditches around it or something. I recommend the 100% deet formulation of OFF if you go there. They are not bad during the day, but soon as it starts cooling off.....
The water in the bypass is sourced from Shasta and it is used for irrigation, but it has water in it all year (and lots of it). During the rainy season or if we get heavy rains, it floods levee to levee. In between the levees, is usually rice, but some areas are not managed at all. It is a wildlife refuge area...so keep in mind, no handguns or rifles are allowed.

The bypass holds a lot of salmon young as well as bass, sunfish, carp, and catfish. If you come in on Sacramento Avenue off of HWY 99 you can see the fish ladder where some creek comes into it...

Water, is pretty warm most of the time and fairly deep. People do drown there due to the current. Where there are low water bridges, you can usually launch a boat etc... Water never clears, it's always brown/green with about 2 inches of visibility. Top water can be fun during summer evenings, but mostly jigs/bait fishermen there. Also, the bypass is a flood plain between two levees... each levee has a large slough that flows next to it...I would say.... 50-80ft wide in most areas...6-10 feet deep. I usually fish the north one as it is more permanent I believe. Cover is unbelievable in most places, lots of timber and weed beds, but not much structure in the bottom. Like someone said... banks are steep when the water is down, no real wading either... but a float tube might be nice, but there is some current. Fishing varies year to year but is usually pretty good. One evening I caught 30+ largemouth on the surface...most of the fish were good size 3-5 lbs.... It's a nice place to fish and hang out, but it can be a "shady" area during the evening.... People do dump bodies down there and stolen cars etc... and yes, I've seen it...