The Huerva is relatively little polluted in its upper course, hence endangered species like the Austropotamobius pallipes crayfish and fishes like Barbus haasi, Rutilus arcasii and Chondrostoma toxostoma are to be found in its waters.
Mississippi River | River Thames | Amazon River | Columbia River | Hudson River | Colorado River | Potomac River | river | Ohio River | Missouri River | Delaware River | Murray River | River Tyne | Madeira River | Volga River | River Nene | River Clyde | River Trent | River Severn | Amur River | River Wear | Allegheny River | Red River | Dnieper River | Yarra River | Paraná River | River Tees | Fraser River | Yangtze River | Tocantins River |