Drainage Criteria

The City of Leander and other Central Texas communities are updating maps in the region following a National Oceanic and Atmospheric Administration (NOAA) study on precipitation frequency (Atlas 14).

As of June 18, 2020, the City of Leander adopted revisions to building regulations and the subdivision ordinance in response to the publication of the National Oceanic and Atmospheric Administration's Atlas 14 Precipitation-Frequency Atlas of the United States. Those revisions included:

  1. The rainfall zones and precipitation data are replaced in the City of Austin Drainage Criteria Manual (DCM) with Leander-specific rainfall data.
  2. Amended stormwater pond freeboard requirements to 1' minimum for all ponds with contributing areas less than 64 acres.
  3. Added an item to the DCM criteria for phased developments discharging to ponds designed and constructed before Atlas 14.
  4. Revised the minimum finished floor elevation for the new home construction or substantial improvements to two feet above the base flood elevation.
  5. Revised the minimum elevation of finished floors or floodproofing for new construction and substantial improvements of any nonresidential construction to two feet above the base flood elevation.

Please view our Drainage Criteria Technical Memo Number 1 (PDF) for more information on the City of Leander's precipitation data.

Please view the NOAA Atlas 14: Precipitation-Frequency Atlas Data (XLSX).