The Great Northern Detention Pond is at 6900 Great Northern Boulevard, near the intersection of Far West Boulevard and MoPac Expressway. This is a small, high hazard dam with an embankment that is 20 feet high. This detention pond helps reduce the risk of flooding for many homes along Shoal Creek in the Allandale Neighborhood. The dam was last inspected by the City in March 2006 and by the state on February 13, 2007 (TCEQ Inspection Report, 344 KB pdf).

A presentation was given to the neighborhood on Monday, February 4, 2008. Download a copy of the presentation (3 MB pdf).

Project History
The detention pond was built in 1978 and was modified in 1983 in response to the Memorial Day flood. A water quality pond was added in 1993. Pond Dam Safety Program staff are currently planning to bring the structure into compliance with state criteria so that the dam continues to provide protection from flooding.

Project Summary
Construction should take about nine months, beginning in late 2008. There are two main components to the proposed upgrade:

• The safety of the structure will be enhanced in the event the dam is overtopped during an especially severe storm. A short wall will partially encircle the pond. It will direct any overflow over a concrete-lined spillway, so that the overflow will not weaken the structure of the dam. The wall will not restrict access to the site.
• Unfortunately, many trees need to be removed, including all the trees and brush on the embankment itself. We have limited the tree removal as much as possible, but it is necessary to ensure the dam remains in good condition. The root systems of trees and brush tend to weaken dams and decrease their ability to resist the force of flood waters.

In addition, a Flood Early Warning System gauge will be installed at this site to allow the City to monitor the site during storms.