Under the SOS regulations, certain watersheds in Austin allow no increase in pollutant load to receiving streams. Retention irrigation ponds capture stormwater in a holding pond and use the captured volume for irrigation of the surrounding landscaped areas rather than allowing direct release to receiving streams. There is virtually no discharge of runoff off-site and it mimics the undeveloped watershed conditions by allowing infiltration of smaller rainfalls. Retention irrigation systems have excellent pollutant removal efficiency.
Environmental Criteria Manual 1.6.9 (Guidance for Compliance with Technical Requirements of the SOS Ordinance)