Areas in relatively dry climates often have water shortages and there is competition between municipal and agricultural (irrigation) water use. The problem can be alleviated by using the water twice, first for the cities and then for agriculture after the municipal wastewater has been properly treated. There are now two sets of water quality standards for irrigation with wastewater: a stringent set for developed countries, and a less stringent set for developing countries. Also, more and more cities will have to use their wastewater internally for irrigation of parks, etc., and even for drinking. The latter requires advanced wastewater treatment. Part of this treatment can be supplied inexpensively by a groundwater recharge and recovery system, which also provides storage and enhances the aesthetics of direct potable reuse of wastewater by breaking the pipe-to-pipe connection. The renovated water from a recharge or “soil-aquifer treatment” system generally can be used as such for unrestricted irrigation, but potable use requires additional treatment.

The 1977 Clean Air Act legally mandated the prevention of significant deterioration (PSD) of air quality related values (AQRVs) on wilderness lands. Federal land managers are assigned the task of protecting these wilderness values. This report contains guidelines for determining the potential effects of incremental increases in air pollutants on natural resources in wilderness areas of the National Forests of California. These guidelines are based on current information about the effects of ozone, sulfur, and nitrogen on AQRVs. Knowledge-based methods were used to elicit these guidelines from scientists and resource managers in a workshop setting. Linkages were made between air pollutant deposition and level of deterioration of specific features (sensitive receptors) of AQRVs known to be sensitive to pollutants. Terrestrial AQRVs include a wide number of ecosystem types as well as geological and cultural values. Ozone is already high enough to injure conifers in large areas of California and is a major threat to terrestrial AQRVs. Aquatic AQRVs include lakes and streams, mostly in high elevation locations. Current sulfur and nitrogen deposition is probably too low to warrant immediate concern in most areas (with the exception of nitrogen deposition at some locations in southern California), although the low buffer capacity of many aquatic systems in California makes them sensitive to potential future increases in acidity. Visibility is considered as a discrete AQRV. Guidelines are presented for determining degradation of visibility based on sensitive views in wilderness areas. Estimates of current deposition of ozone, sulfur, and nitrogen are compiled for all California wilderness areas. Recommendations are included for resource monitoring, data collection, and decision criteria with respect to the disposition of permit applications.