Watershed Wednesday: Septic Systems in Gallatin Valley
There are more than 19,000 septic systems around Gallatin County. The average life of a maintained septic system is 20-30 years, and the average age of tanks around the valley are 25-28 years old. These systems are necessary for the proper treatment and disposal of domestic wastewater, but poor maintenance can contribute pollutants to groundwater which can be linked to public health and pollution issues.
Participants using a septic model and timing how long after overloading the system it takes to leak.
To provide some background, groundwater is the water found below ground in the cracks and spaces in soil, sand and rock, called aquifers. It exists and moves slowly underground in these saturated areas. The upper surface of the saturated zone is the water table. In the confines of the Gallatin Valley, groundwater levels range from 1 foot to 50 feet below the surface of the ground. In the realm of hydrology, shallow groundwater is considered to be less than 50 feet below the surface.
Why is groundwater important? The USGS reports that, “Groundwater is the source of about 37 percent of the water that county and city water departments supply to households and businesses (public supply). It provides drinking water for more than 90 percent of the rural population who do not get their water delivered to them from a county/city water department or private water company.” Nationwide and locally, groundwater is an important resource to protect.
Groundwater always flows downhill, following the gradient of the landscape. Groundwater seepage is important and responsible for keeping water in rivers during times of no rainfall (base flow conditions). To zoom out, Montana is a Headwaters state, and the Gallatin, Madison and Jefferson Rivers confluence in Three Forks to form the Missouri River, that flows into the Mississippi and eventually feeds into the Gulf of Mexico in the Atlantic Ocean. Although impacts could be observed on a neighbor by neighbor level, its interesting to consider downstream impacts.
What can you do as a septic owner? Educate yourself on your tank and how to maintain it. Not all septics are created equally! Common signs that your tank is leaking include the ponding of water or bright green grass above your septic system.
Resources can be found on the Gallatin Local Water Quality District office or website, which includes “A Montana Homeowner’s Guide to Septic Systems”– a comprehensive guide to all things septic. The top four actions the guide suggests are to:
1. Inspect your system (every year) and pump your tank as necessary (generally every 3 to 5 years).
2. Use water efficiently.
3. Don’t dispose of household hazardous wastes in sinks or toilets.
4. Care for your drainfield.
The “Septic Systems: What Happens After the Flush” workshop was hosted by the Gallatin Watershed Council and Sacajawea Audubon Society, and led by the Gallatin Local Water Quality District’s Hydrogeologist Meggie Olson. The informative and hands-on workshop had attendees build their own septic models, and learn about local issues and the negative effects of not maintained systems on groundwater. Please reach out to Meggie Olson at meggie.olson@gallatin.mt.gov with any questions!