Your Trusted Marine construction partner
Since 1919, we’ve worked with clients and engineering firms with high levels of integrity and professionalism. We understand that success is not only measured by our outcome, but also through the process by which our outcome is achieved.
Marine construction & environmental services
Brennan designs and executes innovative solutions to the world’s most complex maritime, environmental, and infrastructure challenges.
We’ve Been Building For Over 100 Years
— EST 1919 —
Brennan is a fourth-generation, family-owned marine construction firm specializing in environmental remediation, dam construction, commercial diving, harbor management, and submarine cable services.
Since 1919, Brennan has worked with public and private owners of water-based infrastructure and operates throughout coastal and inland waterways nationwide.
Contact our Main Office
608-784-7173
What we do
Brennan’s Areas of Focus
Environmental Services
Whether you need dive services to repair underwater concrete or help restore wetlands following a project, J.F. Brennan Company offers a wide variety of services to fulfill your project needs.
Marine Construction
Brennan offers flexible approaches and innovative solutions to successfully restore contaminated waterways and wetlands through innovative tools and research.
Dam Construction
We work on every part of the dam, both above and below the waterline, and our crews have the experience and equipment necessary to work in a variety of conditions, including underwater.
Harbor Services
Our harbor management services provide inland harbor services for utility companies, dry bulk terminals, and specialty large bulk shippers along the Mississippi River.
Submarine Cable Services
We provide a wide range of custom services for comprehensive surface and underwater solutions including submarine cable installation, inspection, repair, and maintenance services.
Dive Services
We have more than 100 ADCI-certified commercial divers on staff throughout the US that specialize in underwater construction.
No Job Too Big or Small
Dive Services
Our teams are trained to the highest standard, utilizing the newest technologies in underwater services to accomplish difficult tasks in near zero-visibility. We specialize in inland waterway and wastewater diving services.
100+
ADCI Certified Commercial Divers
Learn From Our Experts
We share insights on our specialized projects, and feature highlights from our dedicated team members.
![From Crisis to Coordination: The Demopolis Emergency Lock and Dam Repair [with video]](https://jfbdivi.jnbdev.com/wp-content/uploads/2025/06/Thumbnail-Demopolis-video-2-1-400x250.webp)
DISCOVER WHAT’S POSSIBLE!
We tackle complex projects, work hard, provide solutions and celebrate. We’re risk-takers, fast learners, and experts in our fields. Together, we’re redefining our industry.
Safety First, Quality Always.
The J.F. Brennan Company’s Commitment to Marine Safety
We combine environmental stewardship with rigorous safety measures. Our innovative methods ensure the well-being of both ecosystems and our workforce.