Measuring success with water quality requires balancing monitoring and modeling

Post by Eric Booth

Understanding how and why water quality changes through time is an important activity of scientists and natural resource managers. As pressures on lakes and streams increase from changes in land use and climate, the public and governing bodies are pushing for management practices that will improve water quality.

To know whether those practices are working, it is necessary to evaluate their outcomes. Gathering such information comes in two flavors: monitoring and modeling.


Monitoring involves tracking changes in a system over time, often in response to management efforts.

Monitoring, or observation, is at the heart of the scientific method and is very often what the public sees as the primary activity of scientists. It involves measuring an aspect of a system, such as phosphorus levels in lakes, to see if and how much it changes in response to external influences, such as management practices.

Modeling is the act of constructing a representation of reality – typically using mathematical formulas and computers – so we can explore how the system works under various conditions or scenarios that we can’t observe in real time. Modeling can help us identify possible future conditions of the system as a result of different management decisions – for example, future lake phosphorus levels under different ways agricultural land use might change.

So which one is best for managing water quality? (Spoiler alert: it’s both!) Continue reading