Safer, stronger communities: How Megan Johnston is shaping the future of water systems
At a glance
When Megan Johnston joined GHD, she knew she wanted to build a career in modelling. What she didn’t expect was to become a specialist in one of the water sector’s most specialised fields. Now she’s helping organisations understand and manage the health of river systems.
Building capabilities in riverine water quality modelling
Based in GHD’s Buford office in Georgia, USA, Megan is an engineer in the Linear Infrastructure business group, supporting clients in understanding the complex systems that influence communities, waterways and critical infrastructure. Her work spans water and sewer modelling, floodplain and stormwater analysis and water quality modelling.
Although much of her work happens behind a computer screen, its impact extends far beyond the digital environment. The models she develops help utilities, government agencies and infrastructure owners make informed decisions about water reliability, environmental stewardship and flood resilience.
“I do a lot of modelling of riverine water quality, floodplain systems, stormwater systems and water and sewer networks. The riverine water quality work has become its own niche and that’s been really interesting.”
Using models to test future scenarios
At the core of Megan’s role is the ability to predict how systems will perform under different conditions before those conditions occur in the real world.
Her team creates digital representations of natural and engineered systems, enabling clients to test scenarios, evaluate risks and make evidence-based decisions. In many cases, modelling forms part of a larger multidisciplinary project. Before a flood wall, levee or other major infrastructure asset can be designed, engineers need to understand factors such as peak flows, flood extents and storm impacts.
“We might run a model to determine peak flows or potential flooding impacts. That information then becomes part of the design process.”
Other projects are centred entirely on modelling. Megan has been developing a comprehensive water quality model for Florida’s St. Johns River system. The model itself gives agencies and decision-makers a sophisticated tool to evaluate current conditions and test future scenarios.
Megan’s work often focuses on understanding how wastewater discharges, agricultural runoff and other sources influence river health. By analysing factors such as nitrogen, phosphorus and dissolved oxygen levels, the models help stakeholders assess how activities upstream may affect ecosystems downstream.
The tools behind the models
Water quality models often involve hundreds of variables, each affecting how accurately a system reflects real-world conditions. Understanding those relationships requires constantly investigating trends, challenging assumptions and refining inputs.
“You start seeing trends and asking what’s causing them. There are hundreds and hundreds of values that I’m changing and evaluating.”
The complexity of this work makes Megan’s journey particularly impressive. Many of the specialist software platforms she uses today offered limited training resources when she first encountered them. Building proficiency required persistence, self-direction and a willingness to learn through experimentation.
Water modelling is far from a one-size-fits-all discipline. Megan uses a range of software platforms, each designed to answer different types of questions.
Some tools are focused on water distribution and sewer networks. Others assess flood risk, stormwater behaviour or large-scale infrastructure performance. Geographic information systems (GIS) are also a critical part of the process.
“GIS is where everything starts. You need to understand how things relate spatially before you bring them into the model.”
By combining GIS, coding, data visualisation and engineering principles, she transforms large volumes of technical information into practical insights that support planning, design and operations.
Creating impact that lasts for generations
One of the most rewarding aspects of Megan’s work is seeing how technical analysis translates into real-world benefits. The models her team develops help shape infrastructure that can protect homes, roads, hospitals and other essential assets from future flooding events.
Even projects that are less visible play a vital role in everyday life. Reliable water and wastewater services are easy to take for granted, yet communities depend on them every day. By helping utilities understand network performance and prepare for future demands, Megan contributes to the uninterrupted delivery of essential services.
One of the most inspiring aspects of Megan’s story is her willingness to embrace unfamiliar challenges. What started as a general interest in modelling evolved into a specialised career in water quality modelling, requiring continuous learning, adaptability and perseverance.
Beyond project work, she is equally committed to strengthening workplace culture and professional networks. Megan leads the Atlanta offices’ social committee and recently became co-chair of the Young Professionals network for GHD’s East Region, creating opportunities for colleagues to connect, collaborate and grow.
Her journey demonstrates that growth is often built by stepping into new challenges, staying curious and committing to continuous learning. Through both her technical contributions and leadership within GHD, Megan is helping shape stronger water systems and safer and more resilient communities.