Septic Systems in Marine on St. Croix

Keeping Your Septic Operating Effectively


The village of Marine on St. Croix does not have a centralized wastewater and sewage treatment system that serves all residents, like large communities in the Twin Cities. There are three types of septic systems that operate in Marine:

  • Some homes, such as most of the houses on Judd Street and the upper village, are connected to the city’s community collection system.
  • Jackson Meadow has a shared wetland treatment system.
  • The rest of the homes, such a few on Judd Street and most rural properties, have their own private, independent septic systems that are not pumped by the city.

Wondering what type of system your home has?  Contact the city clerk at 651-433-3636, or to find out. Wondering where the septic tank is located in your yard? Look for the “lid” or manhole cover in your yard. It should be clearly visible on the surface.  

Septic System Basics

A septic tank typically holds 750 to 1,000 gallons of sewage and looks like this:

Waste first goes to the septic tank to separate solids from liquids. Microorganisms in the septic tank begin to break materials down. For the most effective septic treatment, it’s very important to avoid damaging the bacteria in your system (more on that below). The bacteria in your tank can also contribute to the formation of a bacterial layer around the pipes in your drainfield, continuing to remove contaminants, making the system even more effective.

Wastewater from toilets, sinks and showers flows through the inlet into the tank. Solids like food scraps and human waste settle to the bottom of the tank while greases and lighter solids float to the top as scum.

The solids and scum are manually removed from the tank; usually this wastewater is pumped from the tank to a drainfield (also called a leachfield) -- an expanse of land under which perforated pipes have been laid. The wastewater is distributed through the pipes and exits into the soil where physical, chemical and biological processes act to filter out harmful bacteria, viruses and excess nutrients. Eventually, the filtered water flows down into an aquifer and re-enters the water cycle and eventually it ends up in the river.


Marine’s Community Wastewater System

Many, but not all homes and buildings in the upper and lower village are connected to a community collection system.

Solids are pumped out by the city public works department. Washington County’s rule of thumb for septic clean-out is every 3 years, but seasonal owners won’t need it done that often. Public works staff use a “sludge judge” to determine if the tank needs to be emptied. If you have questions about when your septic was last cleaned, contact the city clerk at the town hall.

What happens to the biosolids? They are used to add nutrients to the soil. Marine’s waste is combined with lime to raise the pH and kill pathogenic bacteria. It is then broadcast on top of farm fields that have been permitted for such use.

Liquid is removed from each septic system through a series of pumps (lift stations) that move it through the system until it reaches a primary collection point from where it is pumped to the drainfield located north of the city. (The Stugas have a lift station that pumps wastewater directly to the drainfield.)

A lift station looks like a large utility box with a round light on top.

The drainfield is a large subsurface sewage treatment system comprised of 20 cells. The City operates four cells at a time, while resting the others. It redirects flow to a new bank of cells every six months.

Unlike a traditional mechanical treatment plant, a drainfield’s lifespan is difficult to predict. As wastewater percolates into the soil, biosolids and cellular material eventually plug up the pore space between soil particles. When water can no longer drain away, it is pushed towards the surface. The drainfield must then be abandoned and a new system constructed in a different location.

The City is diligent about rotating flow between the cell banks, which allows the others to rest, maximizing the life of the system.


Jackson Meadow's Treatment System

If you live in Jackson Meadow, your home is using a shared Wetland Treatment System that handles wastewater for the entire community. The community has large shared septic tanks. Solid waste is removed by a septic service. Liquid is pumped into a constructed wetland. This wetland consists of a plastic liner, gravel bed, and insulating mulch layer. The water level is kept below the top mulch layer so no water is exposed during the treatment process. Wetland plants and bacteria purify the water as is flows through.

After treatment in the wetland, the water is discharged into an unlined infiltration bed. The pretreated water percolates down through the soil. For more information on this system, see


Private Septic Systems

Homes and buildings not connected to either of the above systems must have their own onsite septic system. There are several types of systems available. The one you choose will be dependent upon the number of bedrooms in the home, the soil type on your site, lot size and slope, proximity to water, and county regulations. 

To see examples of available septic systems, see this guide from the EPA.

Marine on St. Croix can be a challenging place to manage wastewater. Many homes in the lower village rest on bedrock. Much of Marine adjoins wetlands and streams, and eventually the river. Regulations are in place to protect the community and the St. Croix River from water contamination.

If you have a private system, you will have a drain field on your property and you will be responsible for hiring a septic service to remove solids on a set schedule.


How to Keep Your Septic System Healthy

Whether you are on a community septic system, or have your own system, it is important that you know how to keep your septic tank and drain field working properly. Microorganisms in your septic tank are key to the process of breaking down contaminants in wastewater. Those microorganisms can be harmed by things you put down the drain.

  • Don’t use septic tank additives and commercial septic tank cleaners. They are not necessary and could harm your system.
  • Do not use caustic drain cleaners if you have clogged drains. Do not use foaming drain cleaners. Instead, use a drain snake tool.
  • Do not use laundry detergents containing chlorine bleach, phosphates or MEA (ethanolamine). These chemicals are harmful to the bacteria you want in your septic system. Check laundry detergent labels for “septic safe.” (Oxidized bleach is less harmful than chlorine bleach.)
  • For toilet, sink and shower cleaners, check for products labeled septic-safe. Biodegradable and plant-based products are usually safe. Water-based cleaners (those that list water as the first ingredient) are safe for use.
  • Do not flush latex paint, varnish, paint thinner, oil, pesticides, or other dangerous chemicals down the drain.
  • Do not flush “flushable” baby wipes or other types of wipes. Yes, they flush but they do not dissolve. This becomes a problem when biosolids are prepared for field application.
  • Do not put kitchen grease or fats down the drain. They are not easily degraded by the bacteria in the system and can cause blockages in the system.
  • Do not flush feminine hygiene products or condoms.
  • Do not use products that contain methylisothiazolinone, an antimicrobial chemical used in many household cleaning products as well as drain cleaners.
  • Garbage disposals are discouraged. Food will clog the system and you will need to pump it more frequently.
  • Don’t hook your sump pump into the drain system. It should be directed outdoors, preferably 20 feet from your house but not on a neighbor’s lot or onto a drain field.
  • Water softener backwash goes into the septic system, which can raise the salt content of your water – and your wastewater – to undesirable levels. There is an alternative to the traditional water softener, which uses sodium chloride. It uses potassium chloride instead, which does not add sodium to the water.

If you have a private septic system

  • Be sure to direct roof drains and sump pump drains away from your drainfield. Excess water prevents the soil from cleaning the wastewater you need it to clean. That can lead to groundwater contamination and even surface water pollution.
  • To prolong the life of your drainfield, conserve water: Repair leaks, use low-flow faucets and showers, and water-efficient toilets and washing machines.

Regular Maintenance

When you move into your Marine home, have a chat with public works. They will be happy to explain how Marine’s systems work and will provide you with a phone number to call if you have a problem (such as backup into floor drains or very slow drainage throughout the home).

If you have a private system, have your septic inspected every 1-2 years, or if you are experiencing a problem.

  • Do not drive or park over your septic tank or drain field.
  • Plant only grass over and near your septic system. Tree roots can damage your system.


Frequently Asked Questions


How long do septic systems last?

Septic tanks can last 15 to 40 years, depending upon the type of tank you have, soil conditions, nearby trees, proper siting and maintenance, and good general care.


What I do if my system is running slowly?

  • Homeowners on the City’s collection system should call the Marine city clerk at 651-433-3636. 
  • If you have a septic tank on Marine’s system, you own the line from your home to the tank. The City is responsible for problems from the tank onward.  If you think the problem is at the tank or beyond, call the Marine city clerk at 651-433-3636.
  • If you have a private septic system not connected to the City’s system, call a septic professional.


What to do in case of flooding?

You may have a flooded septic tank if:

  • Your tank has been in the ground for years and you suddenly see the ground around it has settled.
  • A few days after the last rain the ground around your septic tank is still saturated.
  • There is standing water above your septic tank.
  • There is a foul odor.

The Minnesota Pollution Control Agency has a useful document entitled “What to do With Your Septic System During a Flood.” Here are its suggestions:

Before a flood

  • Have a plumber install a backflow preventer to prevent sewage from re-entering your home, or plug all drains in the basement
  • Make sure land around the manhole cover above your septic tank is sloped away from the tank, not toward it
  • If possible, seal the manhole cover and inspection ports
  • Document all system components in case they are damaged and you need to file an insurance claim
  • Look up your exact type of septic system to understand if you need to turn off electricity to your pump and how to do so.

During a Flood

  • Avoid non-essential water use. Flush toilets as little as possible.
  • If your drain field is covered with water, do not use your septic system and avoid walking in standing water that may contain sewage (if possible)
  • Use a temporary toilet (see the EPA guide for suggestions)

After a Flood

A flood can damage a septic system as well as contaminate well water. Before you use your septic system again, or drink water from your well, have them checked.


How will you know if your septic tank or drainfield is having problems?

  • All of the drains in your home will drain slowly
  • You may hear a gurgling sound in the plumbing
  • You may have sewage or water back up in sinks, toilets and bathtubs
  • You will see standing water or damp spots on the lawn in the drainfield or around the septic tank
  • You may smell a bad odor
  • The grass over the drainfield is a brighter green
  • A test of nearby well water reveals higher than normal levels of nitrates or bacteria


What can cause your septic system to fail?

Septic tanks can become clogged and overfull, and inlet and outlet pipes can be blocked. You can head off these problems with regular inspections and pumping. Once a problem develops, hire a septic professional.

A septic tank can also develop cracks, especially when there are significant roots nearby. If the cracking is severe, the tank may need to be replaced. Smaller cracks can be repaired.

A home drainfield may become saturated and fail to function to filter water after years of use, from flooding, or if the drainfield was poorly located. In some instances, a drain field can be rehabilitated. In other cases, a new drainfield will have to be found. Contact a septic professional.


What if my septic system is damaged?

  • A damaged septic tank can collapse. Do not walk over it.
  • Do not pump out a septic tank while flood conditions persist. That could cause the tank to float up from the ground. Once the water table is lower, and the ground around the tank has dried a bit, then it can be pumped out.
  • If there is backup or visible overflow of sewage on the ground, stop all water usage.
  • If your system is slow but operating, limit home water use as much as possible. Avoid sending sump pump water into the septic system.
  • Except for mound systems, it can take weeks to a couple of months before a flooded drainfield is dry enough to function properly.
  • The pipes in the drainfield may have become plugged. Talk to a septic system professional before starting up your system again.


What does it mean when the red light is flashing on top of a lift station or a step station?

All lift station pumps and step station pumps on private property have a red light that warns people it is not operating properly. Call the City at 651-433-3636 to report this. If you call after regular business hours, the answering machine will provide a phone number for sewer emergencies and they will come out to check on the problem.


What do I do if my septic system fails?

You will need a permit to repair or modify and existing system, or to install a new septic tank or soil treatment area. Washington County Subsurface Sewage Treatment Systems provides information about permits and inspections.


Can I get financial help to replace a septic system?

Washington County offers low-interest loans for rural landowners not connected to city sewer systems, and fix-up grants for low-income residents. This funding is available for both wells and septic systems. See the Washington County website: