Projects & Studies

(Update: On October 9, 2018, Harris County Commissioners Court authorized the County Judge to execute an agreement with the U.S. Army Corps of Engineers to allow the Flood Control District access to Addicks Reservoir property in support of this project. On March 27, 2018, Harris County Commissioners Court approved a $495,000 agreement with Halff Associates to provide a Preliminary Engineering Report regarding stormwater conveyance improvements on Lower South Mayde Creek.)

Lower South Mayde Creek

Preliminary Engineering Report

The Harris County Flood Control District has begun preliminary engineering on a project to improve the flow of stormwater and reduce flooding risks along lower South Mayde Creek, a tributary in the Addicks Reservoir watershed of northwest Harris County.

A Preliminary Engineering Report (PER), due in Fall 2018, will recommend details for channel improvements between Fry and Greenhouse roads, and will explore the possibility of a bypass channel to increase the discharge of stormwater into Addicks Reservoir. Preliminary engineering activities include collecting survey, geotechnical and environmental field data, as well as coordinating with the U.S. Army Corps of Engineers, which owns, operates and maintains the reservoir.

> Download Preliminary Engineering Report Public Meeting (March 21, 2018)

The creek, which flows into the Addicks Reservoir near Greenhouse Road, has a history of flooding in this area, with structures inundated during Hurricane Ike in 2008, a storm in April 2009, the Tax Day Flood of 2016 and Hurricane Harvey in 2017. The creek currently has a level of service that ranges from less than the 50 percent (2-year) storm near the Addicks Reservoir to between the 1 percent (100-year) and .4 percent (250-year) storm in the Morton Ranch area.

The PER is the next step following a feasibility study completed in 2017, which explored various ways to reduce the frequency of riverine flooding events along South Mayde Creek, as well as their depth and duration. The goal of the feasibility study was to achieve a level of protection equal to a storm that has a 1 percent chance of occurring each year (the “100-year flood”). The feasibility study recommended stormwater conveyance improvements for South Mayde Creek downstream of the Grand Parkway (State Highway 99) to Greenhouse Road, and construction of a bypass channel east of Greenhouse Road on the Addicks Reservoir. The feasibility study also considered the potential for future stormwater detention and retention, as well as property buyouts.

The PER represents a more detailed plan for a portion of the feasibility study recommendations. Channel improvements – widening and/or deepening the channel, for example – could be accomplished within the Flood Control District’s existing 300-foot-wide channel corridor, without the need for additional property acquisition. Construction of the bypass channel would require extensive coordination with and approval by the Corps, as well as a detailed investigation of potential environmental impacts.