Ideas and Insights

ASTM E1527-13 lists historical aerial photographs as one of the standard historical sources used to conduct a Phase 1 Site Assessment. For environmental professionals, aerial photos provide one of the best ways to understand land-use changes over time. They can help identify the location of suspected abandoned sites, determine usage trends, and aid in evaluating when an event may have started to impact a site – as well as the event duration and time of cessation.

Aerial photographs have been contracted by local, state and federal agencies since the late 1930s and with some municipalities as early as the 1920s and some as recent as the 1950s. The most widely used historical collections are from programs authorized by the United States Geological Survey (USGS) and the United States Department of Agriculture (USDA) and their predecessors. Understanding the backgrounds of the collections and their production methods is beneficial in extracting the most value from the resources of their collections. These include but are not limited to NHAP, NAPP and DOQ, produced by USGS and NAIP, issued by the United States Department of Agriculture.

National High Altitude Photography (NHAP)

The National High Altitude Photography (NHAP) program was commissioned by USGS to cover 7.5 minute quadrangles cloud-free over the United States of both black and white and color infrared aerial photographs of the lower 48 states.  The program began in 1978 and was operational until the late 1980s. USGS contracted with aerial photographers around the United States and the photographs were manually assessed to insure they met the strict criteria established by the agency. The chief purpose of NHAP and its successor was to assist in the creation and revision of topographic maps.

The NHAP collection consists of over 500,000 photographs. The black and white aerial photographs were taken at a scale of 1:80,000 and the color infrared photographs were taken at a scale of 1:58,000. The color infrared photographs show vegetation as a red to magenta color and due to film processing degradation some photos have a blue cast. Some of the photos in the collection have feature displacement and scale difference caused by camera tilt and elevation variation.

(NHAP) Color Infrared (1983) Tank Farm Baton Rouge, LA - enhanced to I” = 500’

National Aerial Photography Program (NAPP)

The National Aerial Photography Program (NAPP) was commissioned by USGS to cover quarters of 7.5 minute quadrangles cloud-free over the United States of both black and white and color infrared aerial photographs of the lower 48 states and Hawaii. The program began in 1987 and was operational until 2007, replacing the NHAP program. The aerials consist of both black and white and color infrared photographs.

The NAPP collection consists of over 1.3 million aerial photographs but unlike the NHAP collection, it consists predominantly of photos made at a scale of 1:40,000. Photographs were acquired on 9-inch film and were centered over quarters of the 7.5 minute quadrangles. Flight lines for the NAPP program were flown in a north-to-south direction through the east and west halves of 7.5-minute quadrangles. Like the photos in the NHAP collection, the color infrared photographs show vegetation as a red to magenta color and due to film processing degradation some photos also have a blue cast. Some of the photos in the collection also have feature displacement and scale difference caused by camera tilt and elevation variation.

NAPP Infrared (1989) Tank Farm Baton Rouge, LA - enhanced to 1” = 1000’

Digital Orthophoto Quadrangle (DOQ)

The Digital Orthophoto Quadrangle (DOQ) collection is a smaller (less than 500,000 images) archive of aerial photographs that run from the early 1990s to the mid-2000s with the full coverage of the United States completed in 2004. It is a computer generated image where camera tilt and other displacement has been removed with 1 meter ground resolution. The DOQs are in black and white, natural color and color infrared. USGS produced mostly quarter quadrangles, covering 25% of a full quad. However, areas of Oregon, Washington and Alaska were produced as full quadrangles covering full quadrants.

 DOQ (1995) of El Dorado Chemical Plant, Live Oak, TX

National Agriculture Imagery Program (NAIP)

The National Agriculture Imagery Program (NAIP) is commissioned by Aerial Photography Field Office of the United States Department of Agriculture. The program mandates collection during the growing season or “leaf on” conditions at 1-meter ground resolution. The program began in 2003 on a five-year cycle but switched to a three-year cycle in 2009. Most areas have from three to six years of coverage in more recent years.

The Aerial Photography Field Office mandated strict compliance guidelines and have used both automated and visual quality control mechanisms to ensure compliance. The images are orthorectified and geometrically corrected so the distortion is removed and scale is true and uniform. NAIP photos cover a quarter quadrangle and are natural color or color infrared.

NAIP (2017) of the former Freshkills, NY Landfill site - enhanced to 1”= 1000’

USDA and USGS both produced over 4 million aerial photo frames from the late 1930s through the late 1970s. These photos were predominantly black and white photos and were produced at scales ranging from 1:20000 to 1:40000. Additionally, other federal departments and agencies such as the U.S. Bureau of Land Management, Map Service, U.S. Army Corps of Engineers, National Park Service and the Federal Emergency Management Agency and NASA have all commissioned aerial photography programs during their existence and are all valuable collections in finding resources for environmental due diligence.

Single Frame (1954) of the Fresh Kills NY Landfill

Envirosite’s Aerial Photo Research and Coverage

Envirosite researches all available aerial photos from major historic collections including NHAP, NAPP, DOQ and NAIP as well as historic aerial photos from smaller collections such as state and regional libraries, universities and archives. With access to over 10 million historic aerial photo frames from around the United States – we provide an average of 16 or more photos per report. We research over eight decades of coverage and include two or more photos per decade when available.

Learn more about Envirosite's Aerial Photo solution.