4Bailey R G. Ecoregions of the United States. Map (scale 1:7 500 000) [M]. U.S. : Intermountain Region Press, 1976.
5Omernik J M. Ecoregions of the conterminous United States (map supplement) [J]. Annals of the Association of American Ge- ographers, 1987, 77(1) : 118-125.
6United States Environmental Protection Agency. Federal water pollution control act [Z]. Washington D. C. : United States Envi- ronmental Protection Agency, 2002.
7European Union Commission. The EU Water Framework Dire- ctive--integrated river basin management for Europe [OL]. 2008- 12- 14.http ://ec.europa.eu/environment/water/water- framework/ index en.html.
8Moog O, Schmidt-Kloiber A, Ofenbock T, et al. Does the ecore- gion approach support the typological demands of the EU 'Water Frame Directive' ? [J]. Hydrobiologia, 2004, 516 : 21-33.