Facts About OCWD’s Prado Constructed Wetlands

To commemorate International World Wetlands Day on Feb. 2, we’d like to offer the following factoids about OCWD’s own Prado Constructed Wetlands, located in Riverside County, along the 100-mile route the Santa Ana River travels from the San Bernardino Mountains to the Pacific Ocean.

  • The constructed Prado Wetlands are approximately 465 acres and are comprised of 50 shallow ponds used as a natural water treatment system.
  • They were created in 1996, a modification of ponds used for duck hunting, and before the 1970s, barley fields.
  • The Prado Wetlands are the largest constructed wetlands on the west coast.
  • OCWD diverts approximately half of the base flow of the Santa Ana River through the wetland ponds.
  • The Santa Ana River water is naturally treated in the wetland ponds by micro-organisms and wetland plants that remove pollutants.
  • Prado wetland ponds remove an estimated 175 tons per year of nitrates from the Santa Ana River.
  • The wetlands are a very effective and economical means for nitrate removal at a cost of about $0.85 per pound vs. $15 per pound with conventional treatment.
  • The wetlands are more effective from May through October.
  • The wetlands are found to consistently improve the quality of the river water.
  • Treating the water in the Prado Wetlands is an important first step in protecting the Orange County Groundwater Basin’s groundwater quality before it reaches downstream recharge facilities in Anaheim.
  • In addition to improving water quality, the Prado Wetlands provide an opportunity for water fowl and migratory birds to thrive.