Hydrology concerns follow in designing a site. Precipitation (arid or semi-arid regions demand investigation of water sources), infiltration, evapotranspiration, hydrologic loading rates and water depth can all effect removal of pollutants. A hydrologic budget is suggested by the EPA to guide design of wetlands and provides equations and methods. Water rights can also be of concern and replacement of downstream water may be necessary. Construction must lie above the water table and outside flood plains. Permits and regulatory constraints will also give insight into placement of a wastewater pond. One should consider land use and access, threatened and endangered species and any archeological and historic resources that might be impacted or legally protected. Appropriate agencies must be contacted to determine requirements for zoning and permits. Finally, consider neighbor's opinions and land values, do not site at the edge of a property and use a planted buffer zone.