Use of saline wastewater for revegetation and creation of wildlife habitat.

Abstract

Electrical generating stations in arid regions produce saline water from their cooling systems. Coal fired plants generate fly ash which is recovered by smokestack scrubbers. This ash typically is disposed in large evaporation ponds, which leave vast ash beds and volumes of saline leachate. Restoration of vegetation and wildlife habitat on ash ponds and other impacted areas is complicated by a lack of high quality water for irrigation. I used saline water generated by plant operations to irrigate species of halophytes. These salt tolerant plants were used to revegetate ash ponds and other degraded sites at two generating stations. Once vegetation was established, it provided habitat for wildlife, forage for domestic ruminants, ornamental landscaping, controlled fugitive dust and reduced wastewater disposal costs. At the Four Corners Plant in New Mexico, 16 accessions of Atnplex canescens were tested in a common garden experiment irrigated with saline water recovered from a drainage system collecting leachate from the plant's ash ponds. Accessions from latitudes similar to Northern New Mexico grew faster and had a higher percentage of survival than accessions from more southern or northern locations. Accessions best adapted to an area would be preferable for revegetation projects. I also studied several species of halophytes (Atnplex canescens, A. lentiformis, Prosopis velutina and Paspalum distichum) planted at the Ocotillo Plant in Tempe, Arizona and irrigated with saline water from the cooling system. The vegetation had high survival and growth rates after transplanting. Ground cover increased from 5% to 60%. Surveys of wildlife were conducted pre and post-transplantion. Birds, rabbits and lizards were significantly more numerous in experimental planted areas than in untreated control plots. Rodent populations were not significantly different between treatments. Halophytes can be used to revegetate areas adjacent to electrical power plants and irrigated with saline waters that are normally discharged. Devoting saline water to revegetation irrigation is a cost effective method of disposal compared to evaporation ponds. Plantings attracted several forms of wildlife. Birds, rabbits and lizards specifically used the plants for food, cover and nesting. I developed an economic analysis which compares costs and benefits of restoration projects using halophytes irrigated with saline wastewater.