Well users, including municipal water users, in the WRD area pump about of water per year out of their aquifer. This is an "overdraft" of about of water over what their underground aquifer can "normally" refill. To replace this "overdraft" of water into the aquifer, they have flotation ponds that catch rain runoff water, and supplement with other water they either buy or recycle, then let the water soak into the ground (spreading water) to help replenish the water in the aquifer(s). In addition they buy Colorado River water that is shipped via the Colorado River Aqueduct, and they accept part of the treated municipal wastewater of the about 4,000,000 people in their district and treat it to additional purity and sanitation levels by using reverse osmosis and advanced filtering. Their largest tertiary water treatment facility is the Leo J. Vander Lans Advanced Water Treatment facility. The water out of this facility is better than the water that comes out of the "average" municipal water treatment facility. To finance their water recycling projects WRD charges $268 per acre-foot of water pumped out, which generates about $65,000,000/year. WRD is now on a project (WIN) to enlarge their water treatment facilities to take larger quantities of treated municipal wastewater and treat enough of it that they will not have to buy Colorado River water. Overall it is estimated that this project provides over 40% of the water used in the Southern California district served by the WRD.