The city of Albuquerque, New Mexico Straddles the Rio Grande and is bounded on the north and south by two Indian pueblos (reservations). Several other pueblos are nearby. According to federal Law, Indian tribes are sovereign nations with wide ranging ability to self-regulate and subject to Federal laws and some restrictions imposed by the states. Overall, however their status is closer to that of an equal of state governments rather than a subordinate.
Isleta Pueblo is located on the Rio Grande, downstream from Albuquerque, and is Contiguous to the Albuquerque metropolitan area, which contains approximately 650,000 people. Traditionally, the Pueblo used water directly from the river for drinking during religious ceremonies. In more recent times , this practice has been difficult due to runoff entering the River – storm runoff is directly input to the river - and from treated sewer effluent placed into the river by Albuquerque, Similar effluent is probably discharged into the river by other municipalities farther upstream.
Of great concern to Isleta Pueblo is the concentration of arsenic in the river water. The Albuquerque sewage treatment plant puts water into the Rio Grande that meets all Applicable Environmental Protection Agency (EPA) regulations , including standard for arsenic Concentration . Of course, the water placed into the river is not of drinking quality, since it is assumed that any municipality using river water for drinking must treat the water anyway.