Superfund Site

Toxic Water in the Indian Bend Greenbelt

An Aerial View of the flooding of 1972 An aerial photograph showing the flooding that occurred in the Indian Bend Wash area prior to the creation of the Indian Bend Wash Greenbelt. Source: "Flood Damage in Scottsdale, Arizona 1960s - 1970s," Scottsdale Digital Collection, Scottsdale Public Library, Accessed November 27, 2023. Date: 1972

The Indian Bend Wash had been transformed into an award-winning Greenbelt, but became a superfund site in 1983 as a result of decades of systemic industrial pollution.

After World War II, the area surrounding Indian Bend Wash experienced an explosion of growth. New technology firms moved to the area to manufacture electronics and thousands of people, eager to work the relatively high-paying jobs, followed. The invention of air conditioning also helped fuel the migration of people moving to Scottsdale. By the 1950s, high tech manufacturing giants Motorola, Siemens, and Smith-Kline Beecham built plants in the area and new suburbs sprouted in the farmland along the Indian Bend Wash.

Indian Bend Wash proved both a headache and a valuable resource for industry and residents. Seasonal rains often flooded city streets, damaged homes and businesses, and divided the City of Scottsdale. In 1961 the US Army Corps of Engineers proposed that the city should address the problem by replacing the wash with a 7-mile, 23-foot deep, 170-foot wide concrete-lined channel that ran from the wash's headlands north of Indian Bend Road into the Salt River in the South. Although such channels were the standard method for flood control in desert areas at that time, Scottsdale residents called the proposal an eyesore. Ensuing debate resulted in the "Greenbelt" concept through which floods would be controlled through a series of grassy parks and recreation areas. Completed in the 1970s, the Greenbelt transformed how desert cities controlled water.

Ironically, though, the construction of the Greenbelt did not mitigate a pollution problem that was lurking deeper beneath the surface of the wash. As water that ran down Indian Bend Wash, it soaked through the sand and soil recharging the shallow aquifer beneath it. The city pumped groundwater from the aquifer for residents. However, from the 1950s, before modern environmental regulations, Motorola, Siemens, and Smith-Kline Beecham disposed of their toxic chemical wastes which included Trichloroethylene (TCE), a volatile organic chemical and carcinogen, into dry wells and waste ponds near Indian Bend Wash. This negligent dumping practice continued until the mid-1970s. The waste percolated down into the aquifer and during big rains, the waste would overflow and run into the Wash and eventually soak down into the groundwater. In 1981, TCE was discovered in south Scottsdale water wells.

As a result, the Indian Bend Wash was declared a Superfund site in 1983 when industrial solvents were discovered to have contaminated the groundwater in an approximately 13-square-mile area, affecting both Scottsdale and neighboring Tempe. It became one the largest EPA sites in terms of volume of groundwater treated, estimated at 61.3 billion gallons. Multinational corporations that were partly responsible--Motorola, Siemens, GlaxoSmithKline, and other firms--paid for the approximately $100 million in cleanup costs.

Today, the Indian Bend Wash Superfund site is divided into north and south sections, referred to as NIBW and SIBW respectively. The two sites have different sources of contamination and are on separate cleanup schedules. Over 145 billions of gallons of water have been treated, and the EPA continues to oversee the cleanup and monitoring of the Indian Bend Wash Superfund site.