DES MOINES — Iowa officials said they have completed an effort to map conservation practices that is the most comprehensive inventory in the nation.

An analysis of the results shows the value of the public and private investment in six types of conservation practices — terraces, ponds, grassed waterways, water and sediment control basins, contour strip cropping and contour buffer strips/prairie strips — would be $6.2 billion in today's dollars, according to the project coordinators.

"This mapping effort shows the scale and investment made by farmers, landowners, state and federal agencies, conservation partners and many others over several decades to reduce erosion and protect our natural resources," Iowa Secretary of Agriculture Mike Naig said Tuesday.

"While the practices identified are focused on reducing soil erosion and phosphorus loss, seeing the progress that has been made illustrates how we can make similar progress with a long-term focus and investment in proven conservation practices targeted at reducing nitrogen loss," Naig added.

Additional analysis work is underway to use the science of the Iowa Nutrient Reduction Strategy to quantify the water quality impact these practices are having in terms of reduced sediment and phosphorus loads to Iowa streams, he added.

Practices mapped as part of the project include grassed waterways, contour strip cropping, contour buffer strips/prairie strips, terraces, ponds, and water and sediment control basins in 1,711 watersheds.

The initial number of practices identified by the mapping project include 114,400 pond dams, 327,900 acres of grassed waterways, 506,100 terraces stretching 88,874 miles, 246,100 water and sediment control basins stretching 12,555 miles, 557,700 acres of contour buffer strips, and 109,800 acres of strip cropping, according to researchers.

Iowa Department of Natural Resources officials and researchers at Iowa State University have led the three-year effort to use LiDAR-derived elevation data and aerial imagery to identify and inventory the conservation practices present on the landscape. The analysis is based on LiDAR data — a laser-based detection system — and imagery that was taken from 2007 to 2010.

Coupling assessments such as the mapping project with the known science of conservation practices "allows us to clearly show the impact of farmer efforts on a statewide scale," said Shawn Richmond, director of environmental technology for the Iowa Nutrient Research and Education Council.

Officials said Iowa is the first state to analyze every watershed within its borders using LiDAR and aerial imagery to create a detailed assessment of conservation practice implementation, researchers said. The data allows for a much-more detailed and accurate analysis of soil conservation efforts focused on phosphorus reduction because it includes all practices implemented by farmers, including those done without government cost share.

"This demonstrates that the consistent and persistent effort, year after year, of all the Iowans needed to educate, inform, fund, design, build, and maintain these practices can, practice by practice, change the landscape for the better," said DNR Director Bruce Trautman.

Officials said the completed inventory provides a benchmark for measuring progress. Additional efforts are already underway to assess the status of these practices going back to the 1980s and also to assess the recent status of practices from 2016-2018. Once completed, Iowa will have a robust timeline to show the progress that has been made over time.

Maps and additional information about the project can be found at https://www.gis.iastate.edu/gisf/projects/conservation-practices. Not all of the information is available online yet as DNR officials work to finalize the process of quality assurance/quality control by next spring.

Potential project benefits include targeting resources where they are needed most by comparing conservation potential with actual implementation; accurately benchmarking efforts to quantify nutrient reductions and compare with past and future progress; and creating a consistent, scientifically sound data set vetted by both Iowa State University and the Department of Natural Resources, officials say.

The Iowa Department of Natural Resources, the Iowa State University GIS Facility, the Iowa Nutrient Research & Education Council, the Iowa Department of Agriculture and Land Stewardship, the Iowa Nutrient Research Center, and the National Laboratory for Agriculture and the Environment provided the resources to complete the project.