Sediment is the largest pollutant by volume of surface water in Iowa.
Most sediment comes from agricultural sources. Sediment increases the turbidity of water, thereby reducing light penetration, impairing photosynthesis, altering oxygen relationships, and reducing the available food supply for certain aquatic organisms. It can destroy fish populations in areas where sediment deposits cover spawning beds. Increased sediment also fills lakes and reservoirs. The reduced soil erosion from conservation tillage systems, compared with moldboard plowing or conventional tillage systems, beneficially decreases the problems associated with sediment in water.