I live in the city of Alameda.
The city of Alameda is located in Alameda County, alphabetically the first of California's 58 counties.
Alameda Creek is also located in Alameda County, but it is nowhere close to the city of Alameda. In fact, they are about as far apart as it's possible to get, and still both be in Alameda County.
Like many California creeks, Alameda Creek is often barely a creek at all. In the summer and fall, it can be dry and barely a trickle.
But in the winter and spring, Alameda Creek is as beautiful as any creek you'll find.
The best way to experience Alameda Creek, in my opinion, is to pick a pleasant day in late winter or early spring, when the temperatures are in the mid-50's or low 60's, and the sky is clear and blue, and drive down to Sunol Regional Wilderness, one of the very nicest of the East Bay Regional Parks.
The road to Sunol Regional Wilderness is about a 10 mile dead-end; when you get there, pay your fee and find one of the parking spots at the end of the road. It can get quite crowded on a nice weekend afternoon, but there's always plenty of parking available.
The picnic tables are very nice here, so make sure you bring a nice picnic lunch.
Then, when you're rested up and packed away, set out on the Camp Ohlone trail. It's a wide and gentle gravel road of a trail that follows Alameda Creek upstream. Soon you'll be amazed that, after just a 30 minute drive and a 10 minute walk, you've found yourself in as beautiful a canyon as you'll find in the Coastal Range: here's a great picture.
You can go as long or as little as you want along the trail, but you should try to make it at least to the so-called "Little Yosemite" area, where striking boulders frame a delightful cascade.
If you're energetic, the trails from here run for miles; you can even arrange to walk all the way to Livermore along protected park trails!
That would be a long walk, though, so we were satisfied with our 3.5-mile Saturday afternoon hike, declaring it, all things considered, one of the best Saturday hikes we've been on in a very long time.