The California state fairgrounds in Sacramento has agreed to a new monitoring program to try to keep waste from its horse stables from running into the American River.

The agreement is part of a settlement of a lawsuit filed in 2003 by the California Sportfishing Protection Alliance, a nonprofit environmental advocacy group.

The suit charged that the river and surrounding area were being systematically polluted by urine, manure, soil and soap from the stables that flowed through storm drains on the property.

Cal Expo, an independent state agency that owns the 350-acre fairground facility, has agreed to develop a storm water management plan and “comply with a program of monitoring, testing, and reporting,” according to the settlement