Many areas throughout Boulder are prone to high groundwater levels. This is due to its location at the base of the foothills where precipitation flows downhill and is absorbed into flatter ground. The presence of groundwater can be sporadic and unpredictable, and community members may experience periods of time with groundwater-related issues only to have them resolve or reappear without identifiable causes. Groundwater can be problematic during wet seasons as well as periods of little to no precipitation.

Managing groundwater is the responsibility of property owners. The City of Boulder does not manage groundwater or have infrastructure to manage groundwater. Solutions to groundwater issues may be limited when the volume of groundwater exceeds a property’s capacity to manage it within private property boundaries. In these instances, water may flow over sidewalks or down alleys, allowing algae, ice and other hazards to form and the surface to degrade.

If you believe you are experiencing groundwater issues, a private water mitigation specialists may be able to suggest resources and help you determine which groundwater mitigation approaches may be right for you.

Comprehensive Flood and Stormwater Plan Volume II (available upon request) talks about the challenges of groundwater in Boulder.

Resources

Frequently Asked Questions

Groundwater is the water found underground in the cracks and spaces in soil, sand and rock. It is stored in and slowly omves through soil, sand and rocks in teh ground.

Consider forgoing the basement

Boulder’s code does not prohibit residential basement construction outside of the 100-year flood plain, provided development meets appropriate building specifications. However, when basements are built in areas with high groundwater, ongoing groundwater management will be a component of property ownership and property owners should be prepared to incorporate groundwater management into their home ownership just like other forms of routine home maintenance.

Consider engineered approaches

A water mitigation specialist can investigate possible solutions for your property, including sump pumps, dry wells, French drains and other water management infrastructure. Water mitigation specialists can typically be found working for engineering firms or plumbing companies and help ensure proper installation and maintenance of engineered approaches.

Consider natural approaches

Depending on site conditions, water-loving trees such as native cottonwoods, willows, or mulberries can help dry soggy spots by drawing moisture into deep roots. Whenever possible, route sump pump discharge into a grassy area or vegetated swale instead of onto driveways or streets. End the pipe over grass or small rocks to slow water and prevent erosion. Keep the planted area at least 10 feet from your foundation, use plants that tolerate wet and dry cycles, and include a gentle overflow path. Check the outlet occasionally to clear debris and make sure water soaks in within a day or two.

Mimic the historic drainage patterns

Property owners must mimic the historical drainage patterns over their properties and avoid causing a burden for neighboring or downstream properties. Learn more about groundwater and sump pump guidelines for property owners.

It is not uncommon for some pump discharge to intersect with sidewalks, alleys and other infrastructure. Regulations prohibit discharge to rights of way to avoid dangerous situations from occurring.

The city suspended alley paving operations in 2018. Adding paved surfaces within alleys can be expensive and can introduce other challenges, including drainage and runoff, additional engineering expenses and environmental and usability impacts.

The safe use of alleys is addressed through routine maintenance and scheduled annual inspections and grading as needed. Drainage features such as pans or ditches are incompatible with these routine maintenance practices as they would be disturbed or destroyed in the course of fixing potholes and regrading. The city’s maintenance website provides more information about the alley inspection program.

No. Pipes under sidewalks or through curbs tend to clog, freeze, crack the sidewalk and create trip hazards especially during winter when discharged water can freeze. Therefore, they are prohibited unless you meet site-specific criteria that would allow for a variance. For assistance with determining options in your area and for information about the permitting process, contact the city’s Planning and Development Services Department through Inquire Boulder.

Subterranean structures are prohibited within the 100-year floodplain per Boulder Revised Code section 9.3.3 Regulations Governing the One Hundered-Year Floodplain. Outside of this area, city code does not have a prohibition on construction of basements if proposed developments meet design and construction standards. Discuss groundwater concerns with a design engineer can help inform specific building approaches and whether groundwater management will be a component of the finished structure.

Managing groundwater is the responsibility of property owners. The City of Boulder does not manage groundwater or have infrastructure to manage groundwater. In very limited cases, the city will work with property owners to devise a solution to discharge groundwater from their property. In these cases, a variance to discharge groundwater to the stormwater system may be an option.

To determine if this is the case for your property, contact the city’s Planning and Development Services Department at ROW@bouldercolorado.gov.please submit an inquiry through Inquire Boulder. Private connections to the sanitary sewer system are strictly prohibited as we need to leave room in the pipes for sewage flow and the influx of water can overload the system and cause backups and spills and may contribute to sewer backups into nearby properties.