Riparian Buffers: An Important Practice For Limiting Nutrient Pollution

A riparian buffer is an edge-of-field practice that helps protect Iowa’s waterways by limiting erosion and pollution. Buffers are composed of “multiple rows of trees and shrubs adjacent to the stream with an additional filter of perennial grasses on the outside of the trees” with increasing width with stream size. Buffers enhance wildlife habitat, reduce flooding, and stabilize soils, shores, and banks.

Unlike some other agricultural states, such as Minnesota, Iowa has no requirements for buffers. The practice is currently mentioned in Iowa’s Nutrient Reduction Strategy, but no tracking measures are in place to calculate how many buffers have been implemented or removed. 

A 2016 Environmental Working Group report used aerial imagery to track progress in riparian buffer installation between 2011 and 2014 in eight watersheds prioritized in the Iowa Nutrient Reduction Strategy. The study found that for every acre of buffer gained in Iowa, two acres were removed.

Comparatively, Minnesota enacted a buffer law designed to limit nutrient pollution entering waterbodies from agricultural land and ditches in 2017. Over 96% of lands covered by the law had installed a riparian buffer a year later. According to the Minnesota Board of Water and Soil Resources, “riparian buffers are critical to protecting and restoring water quality and healthy aquatic life, natural stream functions and aquatic habitat due to their immediate proximity to the water.”

In Iowa, riparian buffers could significantly improve the state’s water quality. According to the Nutrient Reduction Strategy, buffers could reduce nitrate concentration by an average of 91% for water passing through the buffer root zone. The Natural Resources Conservation Service estimates buffers would remove up to 50% of nutrients and pesticides, as well as remove up to 75% of sediment from Iowan waterways. Installing a 35-foot-wide barrier standard would only remove 0.05% of agricultural acres from farming and affect [a small amount] 8% of farmers while reducing total phosphorus runoff by 18% and nitrogen runoff by 7%. 

During the 2019 legislative session, State Senator Rob Hogg of Cedar Rapids introduced bill SF 491, which would require the Water Resources Coordinating Council to make recommendations for a pilot project for universal riparian buffers in a subwatershed. Recommendations for the pilot project would include planning, mapping, technical and financial assistance, alternative practices where a buffer is not appropriate, enforcement, and maintenance.

The bill remains alive and ready to be picked up in the 2020 legislative session, where it would start in the Natural Resources and Environment Subcommittee. IEC is connecting with legislators this summer to educate and build support for the bill. Stay connected with IEC to be ready to contact your legislators in the coming session! 

Grace Holbrook
IEC Water Program Contractor

1. clean water
2. nutrient reduction strategy
3. riparian buffers