By Marguerite Huber

Take cover!

It’s a phrase you yell to protect against something headed your way. But did you ever think that phrase could be applied to pollutants? Well, it can – vegetative cover acts as a defense against non-point source (NPS) pollutants, protecting our lakes, streams, and water bodies.

Vegetative filter strips and riparian buffers  are conservation practices that help control the amount of sediment and chemicals that are transported from agricultural fields into water bodies. They slow down the speed of runoff and capture nutrients, keep more nutrient-rich topsoil on farmers’ fields, and reduces impacts on downstream ecosystems.

To improve water quality in large watersheds, conservation managers need to know what the problems are, where the pollutants originate, and what conservation practices work best.  However, investigating all of these factors at the watershed-wide level is a very difficult and complex task. This is why EPA is working with partners to supplement an existing watershed simulation model to estimate the efficiency of riparian buffers.

USDA’s watershed simulation model, Annualized Agricultural Non-Point Source Pollution (AnnAGNPS), is used to evaluate the effect of farming and conservation practices on pollutants and help decide where to put these practices.  AnnAGNPS also predicts the origin and tracks the movement of water, sediment, and chemicals to any location in the watershed.

To supplement this model, researchers from EPA, USDA, and Middle Tennessee State University developed a Geographic Information Systems–based technology that estimates the efficiency of buffers in reducing sediment loads at a watershed scale.

With the addition of this AGNPS Buffer Utility Feature  technology to the USDA model, researchers and watershed conservation managers can evaluate the placement of riparian buffers, track pollution loads to their source, and assess water quality and ecosystem services improvements across their watersheds.

Riparian buffers and other vegetative cover, such as filter strips, are considered an important, effective, and efficient conservation practice that has been shown to protect ecosystem services at a local level. However, their full impact on a watershed-scale is still subject to ongoing research.

About the Author: Marguerite Huber is a Student Contractor with EPA’s Science Communications Team.