The impervious cover data was collected through aerial photography and LIDAR data that were converted into maps. In some cases, there may be areas that were incorrectly interpreted as either impervious or pervious cover. Please call 512-494-9400 if you think the impervious cover on your property needs to be corrected and request an administrative review.
Before you call there are a couple of things to keep in mind:
- The City’s data on your impervious cover may not be the same as the appraisal district’s improvement values on your tax assessment. That is because the City includes driveways, walkways and other impervious areas not reported in the appraisal district data.
- In some cases, the shaded impervious cover shown in the City’s “Find My Drainage Charge” map does not line up with the photograph beneath it. This is due to the aerial photography being taken at an angle, but it does not affect the amount of impervious cover. This is particularly likely to occur with tall buildings.
- Aerial photography is precise to about six inches, sufficient for calculating the drainage charge. Keep in mind that one square foot of impervious cover is less than a penny a month.
For more information about how we collected the data and what is considered impervious cover, please see the other FAQs.