The Alviso Slough extends from the community of Alviso to the south end of the San Francisco Bay. The launch point is from a newish marina with a low profile dock well suited to kayaks and SUPs. Parking and launching are free. The marina is open from 8am until sunset when the automatic gates close (get home before dark!!!).
A slough is where tidal and riparian waters interact. Tidal influence here is considerable with a typical 9-10 difference in water level. Tidal velocity runs about 1.5 mph, so running with or against the tide will impact paddling effort/speed. When time and tide permit, I typically launch an hour or so before low tide, so I have both an outbound and inbound 'boost'. Even at the lowest tides a kayak can launch and navigate this waterway safely.
Low(er) tides provide the best wildlife viewing experience(shorebirds, occasional harbor seal, etc). Higher tides makes the slough seem far less enclosed, but also comes with increased power boat traffic. The slough is bounded by levees that protect Alviso and the surrounding salt ponds, so it is not an 'open water' experience until you make it all the way to the bay (4+ miles).
'Up slough' from the launch point is a narrow channel that passes the old South Bay yacht club, a dock (occasionally) used by commercial shrimpers and then under a number of bridges. The 'sunken boat fleet' has long since disappeared (gentrification hits the slough!) The small tug boat pictured in the my original trip report had the distinction of sinking and being refloated twice. It's gone to a 'better place'. Except for high tide, the navigable water in this direction pretty much runs out at the Hwy 237 bridge (about a mile upstream). If the tide is over +8 feet, there's another mile or so of reed line water to explore. This is a great 'first paddle' for anyone just getting into kayaking. The water is consistently calm and power boat traffic is pretty non-existent.
'Down slough' takes you out to the SF Bay. It's a great conditioning circuit with a lot of natural 'cut off points' if you want a measured distance in a shorter paddling session. 'Beached boats' on the east side is about 1 mile; 'Wood Wier' on the west side is about 3 miles; 'Low Wier' on the east side is about 4 miles; 'Twin Towers' at the mouth of the slough is 4.2. From that point, the SF Bay is to the left and the world is beyond that. It is possible to paddle from Alviso to Palo Alto's launch point, but the round trip is a significant 18 miles or so.
An important wind warning:
Winds on the SF Bay pick up around 11 am and are strongest after 1 pm. Prevailing winds are from the N or NW. Although the slough is 'sheltered' water, I have seen wind driven swells of a couple of feet with occasional/rare white caps. For the most part wind is not a big deal, but if you're not comfortable with chop or quartering tail winds, it's best to paddle earlier in the day (or check the wind forecasts in addition to the tide charts).
An important seasonal note:
Alviso is used by duck hunters during a 3 month season (about October to January). I have no issues with hunting and enjoy well prepared duck much more than most, BUT most duck hunters have minimal water sense and nearly no common courtesy or caution around kayaks. Their boat is just another kind of pick up truck. One size never fits all, and there are some real 'camo clad princes' out there. You can be the judge.
Restrooms; hiking / biking trails; excellent parking and launch ramps; dedicated floating docks for both power boats and kayaks. In 2017 an Alviso entrepreneur opened a bait shop and kayak rental about a block from the marina entrance (look for a converted caboose!).
Free - Free - Free!!
From Milpitas, Highways 680 or 880 take 237 west to Gold Street off ramp. Turn right at the base of the ramp, right again at the next light and them left on Gold street itself (all these turns have traffic signals - you can miss them!). Follow Gold street to the Alviso Marina (there will be a turn or two, but you can already see water).
From Hwy 101 take 237 east to the Gold street off ramp. Turn left at the base of the ramp (go under the freeway), turn right at the first street, then left at Gold Street. Follow Gold street to the marina.
Kayaking, Canoeing, Stand Up Paddling, Kayak Fishing
Flat/Sheltered Water, Open Water/Ocean