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Stormwater Quality

Stormwater Quality

The stormwater quality program works to address issues related to water quality through the urban corridor of the city with the goals of regulatory compliance and improved urban stream health.

The city has a state municipal separate storm sewer system (MS4) permit for stormwater that flows through the city stormwater system and is not treated before entering the creek. The city’s program description document related to this permit is publicly available for review and comment by contacting the Stormwater Quality Program.

Stormwater Quality Program

The Stormwater Quality Program monitors impacts due to urban runoff and tracks ambient conditions in Boulder Creek. 

How to Report A Spill

If you witness someone spilling or dumping any substance within the City of Boulder, or notice an existing spill or discharge please report the spill by calling the Stormwater Quality team directly at 303-916-5563 or emailing [email protected]

You may also call the City of Boulder Public Works at 303-441-3200 during normal business hours or afterhours and your call will be directed.

Please note that all information is kept confidential and callers may also remain anonymous when reporting an illicit discharge.

Tips for Reporting a Spill

  • Estimate the amount of discharge
  • Note the characteristics of the discharge (color, odor, etc.)
  • Never get too close to a strange discharge because it can be dangerous!
  • If applicable and when possible, take information on the vehicle or person(s) dumping the waste

General Information about illicit discharges

What is considered an illicit discharge or spill? This is any discharge into a storm sewer system that is not composed of entirely stormwater. Per Boulder Revised Code, no person is allowed to discharge into or upon the stormwater utility system, any public highway, street, sidewalk, alley, land, public place, stream, ditch or other watercourse or into any cesspool, storm or private sewer or natural water outlet. All stormwater drains go directly to our waterways without treatment. Please help us protect our waters!

Common illicit discharges:

  • Paint
  • Sediment
  • Grease
  • Petroleum products
  • Sewage
  • Sediment from construction activities
Construction Erosion Control Violation
Construction Erosion Control Violation
Illiict Discharge of Paint Dumped Into a Storm Drain and Into a Ditch
Illicit Discharge of Paint Dumped Into a Storm Drain and Into a Ditch

Additional resources for proper waste disposal

Household Hazardous Waste should never be poured down the storm drain or in an area that could lead to the storm drain. These wastes can be disposed of at the Hazardous Materials Management Facility .

Questions about low risk discharge? Click the following link for more information provided by the Colorado Department of Public Health and Environment (CDPHE) CDPHE Low Risk Discharge Guidance Discharges of Uncontaminated Groundwater to Land .

For any additional questions regarding discharges in the stormwater sewer system, please reference the City of Boulder Revised Code Boulder Revised Code (Chapter 11-5-5 Discharges to the Stormwater Utility System) .

Where does a spill into the storm drain really go?

Please Remember: The storm drain systems are separate from wastewater systems; they drain to our rivers, streams, creeks, and gulches without any treatment. The storm drain system is different from the sanitary sewer system because the sanitary sewer does go through treatment before is enters our rivers and streams.

Exemptions: Please refer to the Boulder Revised Code, 11-5-5, for more information on exemptions. 

Stormwater Management in the City of Boulder

When it rains, stormwater flows over pavements and other surfaces picking up pollutants such as debris, vehicle spills, animal waste, fertilizers, and chemicals. These pollutants are carried in runoff from the land surface, to storm sewers, and eventually local rivers and streams without being treated.

How can stormwater be managed?

Effective stormwater management starts by controlling runoff at the source, at our homes and properties. This includes both source control efforts such as removing pet waste and reducing fertilizer use and implementing stormwater control measures (SCMs) to capture and treat runoff. The Keep It Clean Partnership has additional resources for homeowners and businesses on efforts you can take to improve water quality.

What is green infrastructure?

Green infrastructure/low impact development (LID) is the intentional use of plants, soil, and hydrologic processes to treat runoff in a way that matches natural site conditions. Green infrastructure also provides ecosystem services and aesthetic benefits to our outdoor spaces.

Parking Lot Bioretention – Boulder Reservoir
Parking Lot Bioretention – Boulder Reservoir
Parking Lot Bioretention Planter – Avery Brewing
Parking Lot Bioretention Planter – Avery Brewing
Residential Rain Gardens – Trailhead Homeowners
Residential Rain Gardens – Trailhead Homeowners
Roadside Raingarden – 4051 Broadway
Roadside Raingarden – 4051 Broadway

What is the City of Boulder doing to improve stormwater quality?

The City of Boulder aims to take a holistic look at managing stormwater in the city. Stormwater quality is an integral part of City policy and planning efforts including the Comprehensive Flood and Stormwater Master Plan.

The City of Boulder Green Infrastructure Strategic Plan pdf outlines the City’s approach to encouraging the implementation of green infrastructure on both public and private projects.  

Boulder Stormwater Review and Oversight Process

The City of Boulder implements a stormwater review and oversight process in accordance with the State of Colorado Phase II MS4 General Permit . The City’s oversight process starts with development review and continues through construction and permanent operations and maintenance.

What are the City of Boulder stormwater design requirements?

All proposed development projects are subject to the requirements of the City of Boulder Design and Construction Standards (DCS). Development review applications are processed and overseen by City of Boulder Planning and Development Services .

DCS Chapter 7 – Stormwater Design pdf details the design standards, process, and documentation requirements pertaining to stormwater management for new development and redevelopment. The following forms and checklists supplement the Stormwater Design DCS Chapter:

What resources are available to guide stormwater design in the City of Boulder?

The City of Boulder follows the Mile High Flood District, Urban Storm Drainage Criteria Manual and associated Excel design tools (Detention Design and UD-BMP).

The City of Boulder also encourages reference to the City and County of Denver Ultra-Urban Green Infrastructure Guidelines when appropriate for site conditions.

What are the construction stormwater oversight requirements in the City of Boulder?

All new development and redevelopment projects in the City of Boulder are required to implement erosion and sediment control measures in accordance with an erosion control plan.

Projects that disturb greater than 1 acre of land must have an approved Stormwater Management Plan and apply for a City of Boulder Erosion Control Permit pdf.

Stormwater Resources for Property Owners

What are the requirements and procedures for owners of stormwater control measures?

SCM Owners are responsible for the long-term maintenance of facilities on their property to ensure they are functioning as designed.

The Maintaining Stormwater Control Measures (SCMs) Frequently Asked Questions pdf provides additional information on SCM maintenance requirements and owner responsibilities.

The City inspects SCMs periodically to confirm that each facility is adequately maintained and properly functioning. When maintenance needs are identified the city will contact the property owner with required actions. Property owners report maintenance to the city using the following forms:

  1. SCM Maintenance Acknowledgement Form : Used to identify the site contact and acknowledge receipt of a maintenance needs letter.
  2. SCM Maintenance Reporting Form : Used to report completed SCM maintenance actions.

For questions pertaining to the operation and maintenance of a stormwater control measure at your property, please email  [email protected]  .

What resources are available to owners and landscapers to understand SCM maintenance needs?

The City of Boulder SCM Maintenance Schedules and Descriptions and Inspection Forms detail the recommended maintenance and inspection elements by facility type.

The following agencies can provide additional guidance on stormwater facility maintenance:

  1. Colorado Stormwater Center holds trainings and publishes resources related to stormwater facility maintenance including the Inspection and Maintenance Field Guide .
  2. Mile High Flood District provides maintenance information in Chapter 6: BMP Maintenance of the Urban Storm Drainage Criteria Manual.
  3. Keep It Clean Partnership provides a list of resources for facility managers within the Property Management section of their website.
  4. Resource Central provides Outdoor Irrigation Inspections for HOAs and businesses.

The following professional associations may be useful in finding individuals and business with knowledge on stormwater facility maintenance needs:

  1. American Society of Landscape Architects of Colorado
  2. Associated Landscape Contractors of Colorado
  3. Colorado Weed Management Association
  4. Colorado State University Extension, Boulder County

E. Coli in Boulder Creek

The city of Boulder’s stormwater group conducts routine water quality and biological monitoring in Boulder Creek to evaluate current conditions, examine long term trends, and gain a better understanding of the aquatic ecosystem of Boulder Creek.

Safe Recreating Information

When wading or swimming in any natural water body, including Boulder Creek, you may be exposed to E. coli and other microorganisms. Most types of E. coli do not cause illness, but there are certain strains that can cause gastrointestinal illness and symptoms can include nausea, vomiting, stomachache, diarrhea, headache, and fever. Below are some tips to help reduce the chance of illness resulting from E. coli exposure while swimming:

  • Don’t get water in your mouth, eyes or open wounds
  • Stay out of the water if you are sick
  • Wash your hands and shower after being in the creek
  • Don’t swim within in 48 hours of a rainstorm

Four new signs informing the public about safe practices when recreating in the creek were posted along the Boulder Creek Bike Path in July 2020.

What Is E. coli?

Escherichia coli (E. coli) are a large and diverse group of bacteria that typically live in the digestive tracks of warm-blooded animals. When found in our surface waters (rivers, streams, and lakes) E. coli has been used as an indicator of fecal pollution, which can originate from a variety of sources including wildlife, livestock, pets, and sewage. Most strains of E. coli are harmless, but some can make you sick.

E. Coli Fact Sheet

What the City Is Doing to Address E. coli

In 2019, the city developed an update to the previous   E. Coli  TMDL Implementation Plan pdf. The plan lays out the actions the city is and plans to take to mitigate E. coli sources to Boulder Creek. Based on the TMDL Implementation Plan, the city is currently in the process of developing storm sewershed management plans (SMPs) to identify sources of E. coli within the city’s MS4 system. The first plan was developed for the University Hill area of the city and was completed in 2020. For more information, read the April 2019 WRAB Memo pdf and the May 2019 WRAB Memo pdf.

What is a TMDL?

A Total Maximum Daily Load (TMDL) establishes the maximum amount of a pollutant a waterbody can receive without exceeding water quality standards. TMDLs are created for surface waters that are impaired due to prior exceedances of water quality standards and serve as a starting point or planning tool for restoring water quality.

The city developed the Boulder Creek E. coli TMDL in 2011 in response to the creek’s placement on the impaired waters list for bacteria.

The state Water Quality Standard for E.coli in recreational water bodies, including Boulder Creek, is 126 CFU/100 mL. Boulder Creek sometimes exceeds this standard. Levels of E. coli fluctuate frequently.

What you can do to help reduce bacteria pollution:

  • Pick up pet waste
  • Reduce irrigation overspray
  • Keep trash from wildlife
  • Report spills

For more information, visit: 

Stream Monitoring Program

Stream Monitoring Program

The city of Boulder’s stormwater group conducts routine water quality and biological monitoring in Boulder Creek to evaluate current conditions, examine long term trends, and gain a better understanding of the aquatic ecosystem of Boulder Creek.

How and Why Does the City Conduct Water Quality Monitoring?

The city has been conducting water quality monitoring on Boulder Creek for over 30 years. Boulder creek is used for recreation (class 1A), agriculture, and domestic water supply as defined by the Colorado Department of Public Health and Environment. In order to protect these essential stream functions the city conducts water quality monitoring at 15 location along Boulder Creek and its tributaries in order to assess water quality conditions, and monitor compliance with state regulations. Further information on the city’s water quality monitoring program can be found in the Keep it Clean Partnership’s annual water quality report which summarizes the water quality monitoring efforts and results for Boulder Creek and the greater St. Vrain watershed.

What is biological monitoring and how is it used by the city to assess stream health?

Biological monitoring utilizes living organisms (bioindicators) to evaluate the health of the aquatic environment. Aquatic insects, known as benthic macroinvertebrates, are a widely used bioindicator for assessing the health of aquatic ecosystems. Benthic macroinvertebrates are used to detect changes in their aquatic environment based on the abundance and composition of macroinvertebrate families present. The City of Boulder has monitored benthic macroinvertebrates in Boulder Creek since 1995 and is currently conducting monitoring at nine location.