HCFCD Releases White Paper on Flood-Tunnel Pilot Program

8/5/25 – Harris County Flood Control District (HCFCD) has released a high-level white paper on a flood-tunnel pilot program that could cost several billion dollars.

The 15-page white paper lays out a starting point for implementation of the 1,860-page Phase II engineering study released by Black & Veatch in March 2022.

The pilot project would do several things:

Give HCFCD experience with tunnels before full-scale implementation
Create institutional knowledge throughout several Harris County departments (flood control, purchasing, engineering, etc.)
Start reducing flood risk right away
Document proof of concept to help obtain state and federal funding for additional tunnels

Conceptual Overview

Tunnels are a proven concept to help reduce flooding. They have helped other cities, such as San Antonio, Austin, Dallas, Chicago, Washington DC and more.

In Houston, 10-40-foot tunnels placed 50-100 feet underground could reduce the load on creeks and bayous without the need to purchase large amounts of real-estate. Nor would tunnels displace families or businesses.

They might not provide enough capacity to handle a large river, such as the San Jacinto, but they could reportedly make a dent in flooding along smaller creeks and bayous, especially those with dense populations.

Some rights-of-way would require acquisition for intakes, shafts and outfalls, plus subterranean easements.

Total cost of each tunnel would depend on diameter and length.

Primary Recommendations

According to the white paper, Harris County Commissioners Court expressed interest in pursuing two pilot projects:

One would cross Greens, Halls and Hunting watersheds.
The second would run along Buffalo Bayou and help drain Addicks and Barker Reservoirs.

Each would outfall in the Ship Channel near the turning basin and exceed 18 miles in length.

And each could also someday form the “trunk” of a tunnel network that branches out into surrounding areas. So, they could provide both immediate and future benefits.

Other Conceptual Alternatives

The white paper also outlines four other shorter/narrower tunnels that could help reduce flooding. They are primarily in areas that already have stormwater detention basins but inadequate channel conveyance between them. These alternatives include:

Brickhouse Gully from Bingle to TC Jester Park
Halls Bayou from Keith Weiss Park to the Hall Park detention basin east of 59 near the Fiesta.
Hunting Bayou from Lockwood to Buffalo Bayou
Little Cypress Creek for three miles from Cypress Rose Hill Road to the Gulf Club at Longwood

Each of these alternatives is conceptual and would require further study. Initial cost estimates range from tens to hundreds of millions of dollars.

Timing

Pre-construction planning (including preliminary engineering, final design, environmental permitting, right-of-way acquisition, and bidding) could easily take 4-6 years. Construction could take another 2-4 years. So think of tunnels as roughly a decade-long endeavor.