Water quality refers to the chemical, physical and biological characteristics of water. The surface waters of Manassas Battlefield are generally considered to be of good quality. However, the Battlefield is surrounded by busy roads, urban development, and industrial production; all of which have the potential to negatively impact water quality. Water quality can be affected by a number of factors. There is a complicated interconnection of surface water and ground water, atmospheric conditions, natural landscape features, human activities, and aquatic health. Pollution can occur through run-off or seepage, in which chemicals and excess nutrients find their way from point or non-point sources into ground and surface waters. Eroded soil and sediment is another way that excess nutrients such as nitrogen, phosphorous, and pesticides to find their way into rivers and streams. When nitrogen and phosphorous levels rise in a body of water, eutrophication occurs. Eutrophication is the process in which water becomes rich in dissolved nutrients, encouraging algal blooms and plant growth, followed by rapid decomposition. This makes the amount of dissolved oxygen in the water very low and inhospitable to fish and other plants and animals that need access to oxygen in the particular body of water.
Manassas National Battlefield staff works with scientists of the National Capital Region to ensure frequent monitoring of different parameters of water quality. National Park Service staff record the water temperature, pH, dissolved oxygen, specific conductance, nitrogen, and phosphorous levels to observe trends in water quality over time. Volunteers and school groups also play a large role in observing the conditions of the park's surface waters. Bridging the Watershed (BTW) is an outreach program of the Alice Ferguson Foundation, in partnership with the National Park Service and area schools, designed to promote student academic achievement, personal connections with the natural world, civic engagement, and environmental stewardship through hands-on curriculum-based outdoor studies in national parks. Through this program, teachers and students come to the park to perform various water quality assessments of the tributaries of the Chesapeake Bay watershed. Another program, "From the Mountains to the Estuary: From the Schoolyard to the Bay", designed with similar goals and targeted at Prince William County's sixth grade students, utilizes the Battlefield's surface waters for student field studies as well. By introducing students to the importance of water quality through these programs, the staff of Manassas National Battlefield hopes to foster an environmental consciousness in the youth of today that will accompany them well into the future.