In 2001, water supplied by the Authority was found to contain lead levels of at least 1,250 parts per billion (ppb)—about 83 times higher than the accepted safe level of 15 ppb. The discovery was made by Marc Edwards, a civil engineering professor specializing in plumbing who DC Water had hired to investigate complaints of plumbing corrosion. DC Water threatened to cut off Edwards's funding unless he abandoned his investigation. The Centers for Disease Control and Prevention (CDC) released a report dismissing the idea of health risks from the water.