According to Wikipedia: The Clark County Wetlands Park is the largest park in the Clark County, Nevada park system. Located on the east side of the Las Vegas valley, it runs from the various water treatment plants near the natural beginning of the Las Vegas Wash to where the wash flows under Lake Las Vegas and later into Lake Mead.

One purpose of the park is to reduce the environmental impact of the waste water and stormwater runoff leaving the drainage basin area, by building a constructed wetland. 

The second purpose of the park is education. The displays within the park attempt to show visitors how the wash looked before major settlement occurred in the valley and how much impact people have had on the environment.

Some of the native plants, especially those in the areas of standing water, also help to purify the water by removing various pollutants as the slow moving water provides these plants with nourishment. This method of purification is also called natural water polishing.

The park has a visitors center and miles of walking paths.

Open Daily - Free