Wetland Introduction There are about 3,500 miles of streams in New Mexico (Ong et al. 1993). Dahl (1990) estimates that from the 1780’s to the 1980’s New Mexico’s wetlands have decreased by 33 percent, from 720,000 to 482,000 acres. Most of this occurs along streams and rivers due to loss of native vegetation, changes in streamflow, reservoir construction, and other water diversions. In rural areas this can be attributed to conversion to cropland, diversions, and overgrazing. In urban areas the decrease is due to encroachment of residential and commercial construction, water damming or diversion for residential and commercial use, and channelization. Other impacts are clear cutting, burning, and hard-rock mining. These include toxic, acidic or alkaline runoff. Creation of stock ponds and siltation at upper ends of reservoirs offset some, but not all loss. Additionally, the loss of native vegetation along streams alters riparian-wetland functions and allows the proliferation of nonnative vegetation. (Howe and Knopf 1991) Arroyo/Dry Wash This habitat is considered a riparian area by NM PIF. Because arroyos and dry washes contain the characteristics of the surrounding vegetation rather than unique vegetation, they are considered a sub-category within Chihuahuan Desert Shrub, Plains-Mesa Sand Shrub, Great Basin Desert Shrub, and Pinyon-Juniper Woodlands.