How Aurora Protects Waterways

The Clean Water Act amendments of 1972 authorized the National Pollutant Discharge Elimination System (NPDES). Under the NPDES program, the Environmental Protection Agency (EPA) controls water pollution by regulating the discharge of pollutants from point sources -- individual discharge points, such as pipes or man-made ditches. The City of Aurora has two NPDES permits: one permit for its combined sewer overflows (CSOs); and one permit for the municipal separate storm sewer system (MS4).

CSO Permit

  • Aurora developed its EPA-mandated CSO Long-Term Control Plan (Volume 1, Volume 2, Revised Schedule 2011-04-25) and is working aggressively to implement the Plan. The City’s strategies for controlling CSOs include: modifying the overflow structures, constructing new storm sewers to reduce the amount of stormwater in combined sewers, installing green infrastructure to reduce the volume of runoff, and constructing additional storage and treatment facilities. Implementing the plan has cost the City $48.1 million so far and is expected to cost the City another $103.5 million (in 2019 dollars) by the time the scheduled projects are completed in 2030.
    • Projects already completed
      • River Street Sewer Separation (2009-2010)
      • Spring Street Sewer Separation (2010)
      • East Side Rain Gardens (2012)
      • Northeast Sewer Separation (2014)
      • Galena and New York Sewer Separation (2015)
      • Galena and Downer Sewer Separation (2016-2018)
    • Planned projects
      • CSO 01 Treatment and Storage
      • CSO 04 Pumping Station and Force Mains
  • The City and the Fox Metro Water Reclamation District work together to operate and maintain the combined sewer system in Aurora. In order to reduce the magnitude, frequency, and duration of CSOs, theRain Garden Captures Runoff City and the District established operational, maintenance, and inspection procedures for the combined sewer system, which are documented in the CSO Operational and Maintenance Plan. Together, the City and the District implement a range of best management practices (BMPs) designed to reduce the volume of pollutants entering the combined sewer system and also the number of CSOs that occur. These BMPs are described in the CSO Pollution Prevention Plan.  In order to inform the public of the location and occurrences of CSOs, the City and the District are working together to implement this CSO Public Notification Program.
  • Use of the City’s sewer system, and connection to it, are regulated by Section 48-103 and Sections 48-131 through 48-142 of the Municipal Code.
  • The City submits monthly Discharge Monitoring Reports (DMRs) to the EPA. DMRs identify the location and date of recorded CSOs with an estimate of the duration of each CSO. They also present the results of water quality sampling performed at CSO 027.
  • The City is working to prevent basement back-ups and sanitary sewer overflows.  This CMOM Plan documents the resources and procedures used by the City to manage, operate, and maintain its wastewater collection system.
  • The City periodically evaluates the locations of its CSO discharges in order to determine which CSOs discharge to a sensitive area, using criteria established by the EPA.  This Sensitive Area Analysis documents the latest findings.

MS4 Permit

  • The MS4 permit requires the City to reduce stormwater pollution to the maximum extent practicable through six specific initiatives: (1) public education and outreach; (2) public involvement and participation; (3) illicit discharge detection and elimination; (4) construction site runoff control; (5) post-construction runoff control; and (6) pollution prevention for municipal operations.
  • At the beginning of each permit cycle, the City submits a Notice of Intent(NOI) to comply with the permit requirements. The NOI commits the City to meeting specific goals within the term of the permit. Each year the City submits an Annual Report describing the City’s progress toward meeting its goals.
  • Discharges and connections to the City’s storm sewer system are regulated by Section 48-103 and Sections 48-131 through 48-142 of the Municipal Code.