If you like Bird Watching (or wildlife in general), Boating, Fishing, Hang Gliding, Paragliding, Equestrian Activities, Camping or BBQ's, or even history, then this is a place you might enjoy.
The lake and the surrounding area takes on a different appearance depending on the season you visit, and whether it's been a wet year or a dry one. Sometimes when it has been extremely dry, the larger of the 2 lakes dries up either partially or entirely, leaving the smaller one as a valuable water source for Wild Mustangs who live in the area. (which is a great opportunity for photographers).
When the larger lake bed dries up a little, it extends the hang gliding / paragliding landing zone. (take off point is up on the hill on Eastlake Blvd, which is also a good view point of the lakes).
During the wetter years, the larger lake fills up, allowing water activities such as boating to take place on both lakes, and provides you with the opportunity to bird watch at any of the wildlife viewing areas provided. The smaller lake also provides bird watching opportunities (Osprey and other birds of prey like to fish there) You can also fish at the smaller lake, just don't eat them, the area was once used for the processing mills during the mining boom.
Also if you are into wildlife, there is the occasional coyote hunting the area, owls, hawks, bald eagles, and if you want to see deer, take a little drive up Eastlake Blvd towards little Washoe Lake, and one of the fields on the right often has huge herds of Mule Deer, and the occasional wild horse. Talking of Wild horses, you are requested not to feed or harass the wild Mustangs anywhere in Nevada (Washoe lake park included). Horses can be defensive, especially when they have young foals. Also feeding them anything other than what they naturally eat in the wild, not only causes a high number of deaths in the herds, it also creates dangerous situations on the roadways when horses come to retrieve the food. (it can also cost you thousands of dollars in fines) There are people who regularly monitor the interaction visitors have with the horses. But if you want to interact with a horse, why not bring your own for a ride around too, people often bring their horses down for a trot around the grounds.
There are restrooms available throughout the park, and facilities for camping. It is a good place for dogs, though it is requested that you clean up after them. There are doggie clean up stations available, and containers for waste.
The land the park sits on was once owned by one of Nevada's wealthiest men Theodore Winters, who was a prominent businessman and politician in early Nevada history. He once owned some of the most famous racehorses in the world, and his cheese was world renown. His Ranch is still around, and you can find it located just on the other side of the lake (Old Route 395), not far from the Chocolate Nugget Candy Factory (which is great if you get a hankering for something sweet), and Old Washoe City.
The lake's history goes back even further than that, the area was once inhabited by the local tribes people, and before the early pioneer's came and settled here, they used hunt ducks on the lake, and fished here. There is probably still the odd chance you might come across old Native tools and arrowheads, but the State of Nevada does ask you to leave artifacts where they are found. Check the local and federal laws before attempting to remove anything.
It has some lovely sunsets here, the view can be spectacular at times and changes according to season and weather, and the wildlife seem to enjoy it. Nice place to go and hang out with family and friends, and if you happen to forget to bring anything, you are only a little drive from Carson City :)