From the dataset abstract

Aerial Photography and Imagery, Ortho-Corrected dataset current as of 2010. Digital Orthophotography 2010 (Portions re-flown in 2011).

Source: Aerial Photography and Imagery, Ortho-Corrected, Digital Orthophotography 2010 (Portions re-flown in 2011), Published in 2010, 1:2400 (1in=200ft) scale, Washington County Government.