Waterscape: Surface Water This EnviroAtlas national map displays all surface water features identified in the 2011 hybrid National Land Cover Database (NLCD)-Cropland Data Layer (CDL) created by EPA and the National Hydrography Dataset (NHD) version 2.1. Surface water features include oceans, estuaries, wetlands, lakes, rivers, streams, and reservoirs. Why is surface water data important? The national network of isolated and hydrologically- connected waterbodies provide a variety of ecosystem services. Community households, industries, and agriculture nationwide depend on natural lakes and streams and dammed reservoirs to provide drinking water, electric power, Photo source: FEMA irrigation, flood control, and recreation. About 60% of publicly supplied drinking water, most water withdrawn for hundreds of watershed characteristics (such as environmental thermoelectric power, and about half of the water used for traits, sources of degradation, and community factors) that irrigation in the U.S. comes from surface water sources like may influence water quality, environmental health, and lakes and streams.1 quality of life. Depending on its position in the landscape and local needs for various ecosystem services, a waterbody and Waterbodies of all types provide opportunities for tourism and its associated lowland surroundings may provide more benefit recreational activities such as birding, boating, fishing, to the community by removing it from development. hunting, swimming, and sightseeing. More than 27 million Americans participated in freshwater fishing in 2011, How can I use this information? 2 spending over $25 billion. An estimated 46.7 million The map, Waterscape: Surface Water, is a companion map to birdwatchers search for waterfowl, the most highly viewed other WSIO maps covering riparian zones and hydrological group of birds. Stream and lake riparian areas provide connectivity among surface waters. These maps can be important wildlife habitat for foraging, nesting, protective considered base maps for surface water features; they are cover, and travel corridors. Ponds and wetlands contribute to related to a larger group of national EnviroAtlas maps of land climate change mitigation by storing significant amounts of cover in areas of high water accumulation. The two groups of 3 carbon. Depending on their size, lakes and ponds may be maps differ in that the national high-water accumulation maps sources or sinks for greenhouse gases (GHG) such as carbon summarize the data by 12-digit hydrologic unit (HUC) while 4 dioxide, methane, and gaseous nitrogen compounds. the WSIO data depicts surface water features, riparian zones, and the hydrologically connected zone topographically. The This surface water data layer was created for the Watershed WSIO maps may be used as base maps overlaid with other Index Online (WSIO) and Recovery Potential Screening metrics such as protected lands, land cover near water, land Tools in collaboration with EnviroAtlas. The data serves as an cover on hydric soils, and National Wetland Inventory (NWI) important component in creating indicators of water quality. wetlands. They maybe be used in local conservation efforts by Knowing the location of water resources and their overlaying them on an EnviroAtlas aerial imagery base map connectivity is prerequisite to learning how landscape and combining them with specific national EnviroAtlas data attributes and human actions can impact water quality. layers such as Potentially Restorable Wetlands on The condition of a watershed affects the water quality in the Agricultural Land. waterbodies that it contains. Comparing watershed condition Knowing the location of surface waters and potential runoff attributes is one way in which citizens, communities, and their contributing areas can help target implementation of best government agencies learn about their environment, identify management practices (BMPs) to improve water quality.3 Wet water pollution control options, and plan for effective lake, areas maps may be compared with EnviroAtlas impaired river, or stream restoration and protection. There are literally
CONTINUED ON BACK 1 waters data to assist in planning to maximize filtration A large and complex national dataset like the NHD contains capabilities when implementing Total Maximum Daily Loads errors that are attributable to its sheer size, but also to the types (TMDLs) in streams. Wet areas restored alongside or of variables contained within it. For example, a stream’s upstream of impaired stream segments may help reduce perennial status may change during drought cycles or the sediment and nutrient loads to streams. direction of flow of streams may be recorded in error because of water diversions. As a result, portions of the NHD are How were the data for this map created? constantly changing as segments are corrected and updated. This dataset was developed using grid analysis to combine the The level of detail shown is relative to the scale of the data; surface water features of a hybrid of the 2011 National Land the user may have to zoom in to see the higher resolution Cover Database (NLCD) developed by the EnviroAtlas team stream layer. Smaller waterbodies and first order streams may and the 2011 Cropland Data Layer (CDL) produced by the not be shown. National Agricultural Statistics Service with the 1:100,000 scale National Hydrography Dataset (NHD) Plus (version 2.1, How can I access these data? which includes mapped point, linear, and areal surface water EnviroAtlas data can be viewed in the interactive map, features). First, the surface water features—Open Water (11), accessed through web services, or downloaded. NHD, CDL, Woody Wetlands (90), and Emergent Herbaceous Wetlands and NLCD data can be access on their respective websites. (95)—were extracted from the hybrid NLCD-CDL database. Then the flowline and waterbody features represented in the Where can I get more information? catseed grid from the National Hydrography Dataset were A selection of references relating to surface waters and added. The catseed grid contains the seed cells used to ecosystem services is listed below. Additional information on produce the NHDPlusV2 catchments. The combination of the Watershed Index Online and indicators developed using these two datasets, called the water mask, represents all the surface water layer can be found on the WSIO website. categories of surface water features. For more information on For more information on data creation, access the metadata these methods, see the metadata or the WSIO website. for the data layer from the dropdown menu on the interactive map and click again on metadata at the bottom of the metadata What are the limitations of these data? summary page for more details. To ask specific questions EnviroAtlas uses the best data available, but there are still about these data, please contact the EnviroAtlas Team. limitations associated with these data. The data are based on models and large national geospatial databases. Calculations Acknowledgments based on these data are estimations of the truth founded on the EnviroAtlas is a collaborative effort led by EPA. This surface best available science. The landcover classes found in NLCD water layer was developed by the EPA using data created by and CDL are created through the classification of satellite the U.S. Geological Survey. The data layer was generated by imagery. Human classification of different land cover types Gary Davis, EPA (retired). The fact sheet was written by that have a similar spectral signature can result in Elizabeth Smith and Doug Norton, EPA; Megan Culler, EPA classification errors. Student Services Contractor; and Sandra Bryce, Woolpert, Inc.
Selected Publications 1. Maupin, M.A., J.F. Kenny, S.S. Hutson, J.K. Lovelace, N.L. Barber, and K.S. Linsey. 2014. Estimated use of water in the United States in 2010. United States Geological Survey Circular 1405, U.S. Geological Survey, Reston, Virginia. 56 p.
2. U.S. Department of the Interior, U.S. Fish and Wildlife Service, and U.S. Department of Commerce, U.S. Census Bureau. 2013. 2011 National Survey of Fishing, Hunting, and Wildlife-Associated Recreation, FHW/11-NAT (RV), Washington, D.C.
3. Smith, S.V., W.H. Renwick, J.D. Bartley, and R.W. Buddemeier. 2002. Distribution and significance of small, artificial waterbodies across the United States. The Science of the Total Environment 299: 21–36.
4. Tranvik, L.J., J.A. Downing, and 25 other authors. 2009. Lakes and reservoirs as regulators of carbon cycling and climate. Limnology and Oceanography 54(6, part 2):2298–2314. United States Environmental Protection Agency. 2016. Healthy watersheds: Protecting aquatic ecosystems through landscape approaches. United States Environmental Protection Agency, Office of Water. Accessed May 2016.
EnviroAtlas: Led by the U.S. Environmental Protection Agency
March 2018