To clean you can spot clean the affected area with a mild detergent such as those commonly used for washing.
For a larger area, please see steps below
1. Hose down the rug
2. To Clean rug use a soft detergent and soft scrub to softly hand scrub the rug
3. Rinse thoroughly
4. Hang the rug back side up on a fence/clothes line or on anything that is elevated from the ground in order for the water to drip out of the rug while still in the sun