First, and to get this out of the way: "canals" here are not waterways in the UK sense of the word. The canals these trails run alongside are concrete EBMUD water and drainage channels; often bordered by wildflowers and home to families of ducks, but not quite as romantic as Britain's canal network.
The start point of Arbolado Park is the same as for a previous hike into Lime Ridge Open Space. For that hike, we parked on the street on Arbolado Drive, so I do the same today. On my way down to the trail, though, I notice that there's lots of free parking for Arbolado Park. Never mind.
The stretch on Ygnacio Canal Trail is OK; a little bit too suburban, a few too many roads to cross. (The crossing across Bancroft is particularly nasty; California law is "pedestrians first", but in practice it's still "step out and hope they stop".) But there's still a lot of wildlife: crickets chirping alongside the trail, birds drinking from the canal, and lots of rustling in the undergrowth: lizards, I think, although they move so fast that I was only sure of a few sightings. At one point, I pass a family of ducks cruising along the canal: two adults, twelve fluffy ducklings.
Near San Miguel Park, the trail merges with the Briones–Mt. Diablo Trail: a trail I've encountered before, further south, as it passes through Shell Ridge Open Space.
The trail crosses Ygnacio Valley Road, thankfully this time at a light, and then becomes hard to find again. It actually restarts slightly east along Ygnacio, running in a small fenced-off strip between the parking lots of a church and the neighbouring apartment block before running north alongside a small junkyard. Stick with it, it does get better.
I lost the trail again here. From the trail map and Google's satellite view, it appears to run along the back of the restaurant and parking lot on Marchbanks Drive. On the ground, not so clear; easier simply to walk along Marchbanks Drive past the pool and the gardens. From Marchbanks Drive the trail runs north through Heather Farms Park; this stretch is nice, as part of the park is set aside as a wildlife preserve. Lot of waterbirds here: the ubiquitous ducks and geese, but I also see a grebe paddling along the canal.
North of Heather Farms, the Briones–Mt. Diablo Trail connects with the Contra Costa Canal Trail, which runs east all the way to Lime Ridge Open Space. This is a much better trail: wide, green, quiet, with few roads to cross. Lots of ducks. And it's here that I witness some rather disturbing duck behaviour: a mother duck with a brood of fourteen ducklings trailing behind her turns on one of them and drives it away. It trudges rather sadly up the opposite bank of the canal, wriggles through the fence, and disappears into the undergrowth, fate unknown. Was it one too many for her to cope with? Or maybe a tagalong stray whose cover got blown? Distressing, but that's life in the duck world I guess.
The hike saves a treat for the last few miles. At the edge of Lime Ridge Open Space, the Contra Costa Canal trail reconnects with the Ygnacio Canal Trail, which heads south back towards the start point. But it also heads upwards: not far, but far enough to give a good view back over the trees and houses down in the valley where I've just hiked.
The hills of Lime Ridge look tempting from here, too: a loop around this section of the Ygnacio Canal Trail and up into Lime Ridge would make a good hike. No formal trailhead parking here, but one could easily park on the street on Citrus Avenue or Rock Oak Road.
The trail continues south, going under Ygnacio in a long narrow tunnel; along the edge of the Boundary Oak golf course; and back to the start point at Arbolado.
In total, just short of 8 miles; and just shy of 2½ hours. I'm not sure I'd bother with the suburban stretch of the Ygnacio Canal Trail again, but I did like the stretch near Lime Ridge, and I thoroughly enjoyed the Contra Costa Canal Trail: worth returning to explore more sections of it.