This left the steel underneath subject to corrosion. Approximately 25 percent of pipe used in Tucson area homes is estimated to be galvanized steel. Tucson water mains are mostly asbestos cement and galvanized iron. By 1998-99, approximately 140 miles had been replaced. High salinity levels also can reduce crop yields and affect the growth rates of some landscape plants.
Soil salinity is controlled by water quality and irrigation practices.
Salt tolerance of vegetation varies greatly. Citrus has low salt tolerance, but bermuda and rye grasses tolerate salts well. U.S. Department of the Interior, Quality of Water - Colorado River Basin, 1997. CAP water has about 2.5 more TDS than Tucson groundwater, but most of the CAP salinity comes from salts that are benign to plants in the soil-plant environment. Dissolved gypsum and calcium carbonates, found in CAP water, are also common minerals in the semi-desert soils.