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Wetlands, Riparian Zones, and Springs
Wetlands
Of the total wetlands that probably existed in Nevada prior to settlement, 52 percent have been lost (i.e., converted to another type of land cover or use) (Dahl, 1990). The largest regional wetland losses have occurred in the terminal basins of the Truckee, Carson and Humboldt rivers, where an estimated 82% of the wetlands have been altered (Thompson and Merritt, 1987).
The distribution and size of wetlands naturally vary between wet and dry periods. Losses are primarily attributed to the diversion of streamflow for agricultural, municipal,  and industrial uses; filling and draining wetlands for development; and, stream channel erosion and modification. Information on the ecological and water quality status is limited for most wetlands. Additional factors affecting wetland quality include: non-native plant invasions (e.g., tamarisk, perennial pepperweed, and hoary cress); discharges from irrigated farmland, abandoned mines, and urban stormwater containing high levels of salts and metallic compounds; and livestock and wild horse grazing that has not been properly managed. Wetlands and riparian areas cover a relatively small amount of land in Nevada, but the benefits far exceed the area occupied. Wetlands are protected under the Clean Water Act and receive substantial attention from natural resource managers for several reasons.
- The diversity and abundance of vegetation and wildlife is higher in wetlands than any other ecosystem in Nevada.
- Water quality is better because lake and stream banks are more stable, vegetation provides cooling shade, and pollutants from surface runoff are filtered.
- Water is stored and released more slowly from channel banks and floodplains to adjacent waterways.
- Wetlands create habitat conditions required for the reproduction and survival of many fishes and other aquatic species.
- Recreation opportunities are high - hunting, fishing, wildlife watching, and scenery.
- Highly productive plant communities provide abundant forage and cover for the large number of wetland dependent wildlife
Different criteria are used by agencies to classify wetlands to reflect variation in statutory protection and management objectives. The US Army Corps of Engineers (USACE) has primary authority under Section 404 of the Clean Water Act for protection of "jurisdictional" wetlands - those that meet strict regulatory criteria for soil type, water dependent plant species, and period of saturated soils or inundation. The federal wetland policy of "no net loss" is not necessarily a one-for-one replacement objective. More acres may be required to 
be restored for mitigation than the amount drained or filled. The determination is based on an evaluation of the socioeconomic values and ecological functions of impacted wetlands. The federal policy and permit requirements may substantially deter unnecessary wetland losses.
Federal regulations provide for two permit types. A nationwide permit covers many routine land use activities that typically cause minimal impacts. An individual permit must be obtained for projects that could impact wetlands significantly.
The process is involved, requiring application, public review and comment, scientific studies, and assessment of project alternatives to avoid, minimize, and mitigate impacts. The NDEP is involved in wetland protection through section 401 of the Clean Water Act. The provisions give the state's water quality standard setting agency the
authority to deny projects in wetlands that could degrade water quality. During the period 1989 to 2000, the USACE permitted 700 acres of wetlands for conversion to another land use and required mitigation totaling 998 acres (U.S. Army Corps of Engineers, 2001). Mitigation data is not sufficient to determine whether there is a net gain or loss of wetlands. The USACE is working on improved enforcement and tracking of wetland mitigation projects.
The U.S. Fish and Wildlife Service (FWS) uses a broader definition of wetlands than the USACE for mapping wetlands. Riparian zones are more likely to be included in the wetland classification used by the FWS. State-by-state mapping was performed in the 1980's for the National Wetlands Inventory (NWI) project using aerial photographs shot in the summer from 1980 through 1986 and limited field verification. A statewide series of reconnaissance level (1:250,000 scale) wetland site maps was prepared. Five major categories of wetlands were identified:
- Wetlands less than 10 acres - a range of small and diverse wetlands such as vegetated springs and seeps, seasonally flooded vegetated wetlands, temporarily flooded unvegetated flats, and permanently flooded ponds. The size of individual wetlands could not be determined.
- Wetlands between 10 and 40 acres - the same types as the smaller size category of wetlands.
- Wetlands greater than 40 acres - classified based on vegetation or, if unvegetated, based on substrate. The total number of acres for these types was determined.
- Wetland/upland complexes - comprises several small wetlands too close to map individually.
- Linear wetlands (miles) - unvegetated, intermittent streambeds or woody or emergent wetlands in stream course or drainages.
The NWI mapping provides the only statewide statistics on wetlands available. About 1.7 million acres of wetlands were delineated. The total only includes wetland areas greater than 40 acres, wetland/upland
complexes, and playas. Table 3-10 shows the areas covered by different types of wetlands greater than 40 acres separated by type. The amount of vegetated wetlands by type is shown in Table 3-11.
In addition, the mapping identified 30,547 wetlands less than 10 acres in size; 1,370 wetlands between 10 and 40 acres in size; and 29,810 miles of linear wetlands. Acreages are not estimated for these. The surface area of lakes and reservoirs was estimated to be 364,800 acres of lakes and reservoirs, in addition to the 1.7 million acres of wetlands (U.S. Fish and Wildlife, 2001b). Open water and wetlands cover about 0.5 percent and 2.3 percent of the state, illustrating how limited are aquatic habitats. Wetland size data separated by county is shown in Table 3-12.
Protection and rehabilitation of wetlands is challenging because of the competition for land and water resources required for increasing urban, agricultural, and transportation system developments. Projects by NDOW, NDSL, and federal agencies to purchase water rights for premier wetland areas provide for long-term stabilization of core wetland habitats. In some cases, however, sufficient water may not be available during drought conditions. Most significant wetland areas in Nevada are located within state wildlife management areas, federal wildlife refuges, tribal lands, and other specially designated management units. The NDOW has acquired or leased large tracts of land to establish 12 wildlife management areas (WMA's), 10 of which contain 59,250 acres of wetlands and open waters. A wetland conservation plan will be developed for each by the Division with public input.
A variety of wetland conservation and improvement projects are underway throughout the state. For example, in Oasis Valley, The Nature Conservancy has purchased a perpetual easement for riparian wetlands through the Wetlands Reserve Program, which is
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Table Notes: Competing demands for water reduced the wetland acreage more than 90 percent, to less than 10,000 acres. By 1992, several years of drought caused the wetland acreage to drop below 2,000 acres. Meanwhile, Congress in 1990 passed the Truckee-Carson-Pyramid Lake Water Rights Settlement Act. The legislation established a program to acquire from willing sellers water and water rights sufficient to maintain a long-term average of about 25,000 acres of wetland habitat on the Stillwater National Wildlife Refuge, Stillwater Wildlife Management Area, Carson Lake, and the Fallon Paiute-Shoshone Indian Reservation.
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administered by the U.S. Natural Resources Conservation Service. The site is on a ranch near Beatty. Riparian habitat will be restored or enhanced on 190 acres to benefit two special status species, the Amargosa toad and the Oasis Valley speckled dace, and other wildlife and wetland species.
Another project is centered on the Las Vegas Wash. The site of 2,000 wetland acres in the 1970's, the wash became seriously eroded when runoff from urban development and discharges from wastewater treatment plants increased. The wetland area was reduced to 400 acres. Citizen organizations, local utilities, and government agencies are cooperating in the implementation of a comprehensive plan that concentrates on erosion control, environmental monitoring, and wetland construction. Primary benefits include improvement of water quality entering Lake Mead, outdoor recreation opportunities for Las Vegas Valley residents and visitors, and more diverse, healthier habitats for Mojave Desert wildlife.
The FWS is leading a multi-party effort to recover a portion of the wetlands in the Lahontan Valley wetlands complex in western Nevada. This area is a critical stopover for migrating shorebirds and one of 14 Western Hemispheric Shorebird Reserve Network sites. When sufficient water is available, up to 70 percent of Nevada's migratory waterfowl population use the wetlands. More than 175,000 waterfowl regularly stop in the valley during migration, and peak counts of up to 475,000 birds have been recorded. Historically, the Carson River sustained an average of about 150,000 acres of wetlands in the Lahontan Valley.
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