Irrigated mountain hayfields function as filtration systems reducing sediment, phosphorus, and contaminants from runoff, according to Colorado State University research. A three-year producer-driven study examined agricultural impacts across the Yampa, Gunnison, and Colorado River basins.

The investigation discovered consistently low nutrient concentrations in runoff from Colorado hayfields—sometimes lower than applied irrigation water. Erik Wardle, Agricultural Water Quality Program director, noted that “irrigated ag lands in the mountains are essentially large grass filter strips” with minimal environmental impact.

Excess nutrients like nitrogen and phosphorus trigger algal blooms harmful to aquatic ecosystems. The research demonstrates that Colorado’s mountain meadows, managed with judicious nutrient application, naturally prevent fertilizer runoff similar to planted grass buffer strips.

The Colorado Ag Water Alliance, supported by the Colorado Department of Public Health and Environment and EPA, requested the study after producers questioned whether hay production contributed nutrients to mountain surface water. Participating ranchers tested different management practices to optimize fertilizer use.

Carlyle Currier, Colorado Farm Bureau President, validated results showing water leaving his field possessed better quality than irrigation water applied. The successful research has prompted a new Colorado Water Plan project in the Yampa River Basin focused on demonstrating best management practices.

Source: Colorado State University