City of Bend

The City of Bend has enacted stormwater ordinances and a stormwater management plan in order to prevent localized flooding, to ensure public safety, and water quality issues focusing on protecting both our surface water, such as the Deschutes River, and our groundwater resources.  


The City of Bend has stormwater service charges to raise funds for maintaining, repairing, and expanding the City’s stormwater system while complying with federal and state water quality regulations.


Stormwater Rates

The monthly stormwater service charge is based on impervious surface coverage, and is set at $4 per Equivalent Residential Unit (ERU).  Impervious surface coverage is defined by the City of Bend as: A hard surface area that either prevents or retards the entry of water into the soil mantle.

Common impervious surfaces include: building roofs, walkways, patios, driveways, parking lots, concrete or asphalt paving, gravel roads, and packed earthen materials. One ERU is equivalent to 3,800 square feet of impervious surface coverage, which is the average amount of impervious surface for a single family residence in Bend.


Appealing Stormwater Fees

If you feel that the impervious surface coverage, as calculated per the definition above, for your site is incorrect, the City has developed an appeals process. There are also credits available for non-residential properties that maintain stormwater best management practices and facilities on-site.

The instruction sheet on the appeals process can be found here:

[City of Bend Stormwater Impervious Surface Coverage Appeals Information and Instruction Sheet]



Credits are only available when on-site stormwater systems go beyond the basic requirements described in the Central Oregon Stormwater Manual (COSM). Until such time that the City adopts its own version of the COSM, project proponents are expected to follow the procedures in the COSM when designing stormwater systems in the City. An electronic copy of the COSM is available on the City web site and at This manual was developed by and for Central Oregon. It is based on good engineering practices and standards and is, therefore, appropriate for use by stormwater professionals. The City of Bend’s revised (2007) Standards and Specifications will incorporate and refer to the Bend Edition of the COSM.


Quantity and Quality Credit Procedure

The City has determined that owners of non-single family residential (NSFR) properties should be allowed credits when their on-site stormwater management exceeds basic requirements. This is in recognition of the fact that better on-site management will reduce the city’s stormwater management costs.

There are two ways NSFR property owners can reduce their stormwater service charge. One is to reduce the amount of impervious surface on their site; the other is to manage stormwater quantity or quality on-site in a manner that exceeds basic requirements. Reducing the amount of impervious surface does not qualify for credits. Rather, it merely reduces the amount of impervious surface that the owner will be charged for. A separate appeals process is available that deals with impervious surface area reductions.

Bend’s stormwater management is unique and requires a unique approach for determining credits. The chosen approach is to use a hydrologic model to determine the effects of different levels of on-site management on runoff volume and rate. Several different modeling approaches and examples are included in the Central Oregon Stormwater Manual (COSM). The City will accept the results of an appropriate COSM model for determining credits. Those who choose to use a different approach should first consult with the City Engineer.

Stormwater systems cannot be designed properly without the use of an appropriate hydrologic model. It is important to understand that, for the purpose of stormwater service charge credits, modeling will only be used to determine the relative benefits of on-site systems that exceed basic requirements. Therefore, the same modeling approach that is used to determine if basic requirements will be met must be used to determine the benefits of exceeding the basic requirements.

The credit calculations should be applied to each drainage area that results in a separate discharge from the site. The amount of credit will be applied to the impervious area contained within the individual areas.


Basic Requirements

Chapter 2 of the COSM lists these eight basic requirements for stormwater management that a required for new development and redevelopment projects:

  • Basic Requirement #1 – Drainage Submittal;
  • Basic Requirement #2 – Geotechnical Site Characterization;
  • Basic Requirement #3 – Water Quality Treatment;
  • Basic Requirement #4 – Flow Control;
  • Basic Requirement #5 – Natural and Constructed Conveyance Systems;
  • Basic Requirement #6 – Erosion and Sediment Control;
  • Basic Requirement #7 – Source Control; and,
  • Basic Requirement #8 – Operation and Maintenance

Not all of these basic requirements apply to every project, but those that do apply must be in place before credits will be considered. Subsequent chapters of the COSM explain each of these basic requirements in detail and provide design criteria and examples.

The City wants to encourage property owners to improve their stormwater management systems. Therefore, the City has determined that, for re-development, the owner may make improvements that clearly reduce the volume or rate, or improve the quality, of the stormwater leaving the site without having to upgrade to meet the basic requirements that would otherwise apply. For example, a re-development project that does not involve a change in use or increase in impervious area that could result in more pollutants being discharged from the site would not have to meet the basic requirements.

Owners of NSFR properties wishing to earn credits can manage the following properties of the stormwater that leaves their site:

  • Volume
  • Rate
  • Quality

Each of these is discussed below.


This is the volume (gallons or cubic feet) that runs off the site during a design storm event.

It is reasonable to assume that the city’s stormwater costs are linearly related to the volume of stormwater collected, treated, conveyed and disposed of during a design storm runoff event. In the COSM, the basic quantity design storm is the 25-year, 24-hour rainfall event.

Since it is difficult and expensive to measure the volume that runs off a site, credits are based on design values. 


In lieu of, or in addition to, reducing the volume of runoff, the owner may choose to reduce the peak runoff rate. Reducing the peak runoff rate from a site by means of infiltration or detention allows the city to use smaller conveyance systems. Chapters 7 and 8 of the COSM cover Flow Control and Conveyance, respectively.


The COSM contains treatment efficiency goals. The Oregon Department of Environmental Quality (DEQ) approves treatment designs and requirements for underground injection controls (UICs). Because underground injection and piped systems are side-by-side in a large part of the City and pretreatment standards have not yet been developed specifically for discharges to the Deschutes River, City staff has determined that the Best Management Practices (BMPs) required by the DEQ for underground injection systems should also apply to the piped systems that discharge to the river. This will continue until discharge-specific standards and BMPs have been developed.

The City does not expect that NSFR property owners will find it feasible to remove pollutants that the DEQ does not require to be removed, or to remove them more efficiently than the DEQ requires. However, owners may choose to pre-treat more than the minimum 6-month 24-hour water quality storm runoff. For this reason, quality credits are based on the same approach used for volume credits except that the base design storm is the 6-month instead of the 25-year storm. The City does not expect to derive any financial benefits from owners treating more than the 5-year storm event.

Examples of Volume, Rate and Quality credit calculation can be found in the full [Bend Stormwater Utility Service Charge Credit Program Application Packet] as well as the forms for application.


Private Management of Public Stormwater

Under Oregon Drainage Law, property owners must accept natural flows of stormwater and must not unreasonably alter natural flows from their property to neighboring properties. Development will alter natural flows in violation of Oregon Drainage Law unless owners properly manage their stormwater.

The responsibility for handling stormwater within the City is shared between the City and other property owners. Unlike most cities, Bend does not have a piped stormwater system except in a small part of town near the river. In the past, the City has designed its streets to handle a portion of the runoff from private properties but not all of the runoff it is getting. This causes the street drainage systems to be overloaded and water to flow from the street to private property. The City believes that its street drainage systems are generally capable of handling the stormwater for which the drainage systems are designed. The only way to determine if street drainage is under-designed is for owners of private properties that contribute flow to the street to retain their stormwater as required by City codes, standards and specifications. Therefore, except for the special case discussed below, the City will not accept applications for credits based on private management of public stormwater.

The exception is where the City street is the only possible origin of the water that flows onto the private property and this flow is in excess of what would naturally flow onto the property. Owners who believe this exception is applicable to their site are encouraged to submit a proposal to the City. The City may grant credits or upgrade its street drainage system to alleviate the problem. It is important to note that the soil and other characteristics in and around Bend are such that pre-development runoff in most areas was essentially zero even for storms with return periods of 100 years or more.

If there are other exceptions, the City will generally upgrade or change its drainage system rather than grant credits.


Stormwater System Maintenance Agreement

Responsible Party

Owners are responsible for the operation and maintenance of stormwater facilities on their property.

Requirement for Stormwater System Maintenance Agreement

If a project requiring a Drainage Submittal requires structural or nonstructural measures, the owner shall execute a Stormwater System Maintenance Agreement prior to the City granting final approval of any development plan or other development for which a Permit is required under this Title. The Stormwater System Maintenance Agreement shall be recorded in the office of the Deschutes County Clerk and shall run with the land.

Required Elements for Stormwater System Maintenance Agreement

The Stormwater System Maintenance Agreement shall be in a form approved by the City, and shall, at a minimum:

  1. Require the owner of the property, including successor owners, to maintain the stormwater system on the property so that the system continues to function as planned.
  2. Grant the City the right to enter the property at reasonable times with at least 24-hour notice except in instances of emergency to inspect the system and take corrective action.

Maintenance Responsibility

Property owners shall maintain in good condition and promptly repair and restore all structural and non-structural stormwater BMPS, and all necessary access routes and appurtenances (e.g., graded surfaces, walls, drains, check dams and structures, UICs, catch basins pipes, vegetation adjacent to the inlets and within the facility, erosion and sedimentation controls, and other protective devices).

Maintenance Records Required

The owner or other responsible party shall make at least annual inspections of the facilities and maintain records of such inspections. Stormwater BMP inspection, maintenance and repair records shall be retained by the owner or their designee for a period of five years, and shall be made available to the City upon request.

Maintenance Inspection by Stormwater Authority

The City shall retain the right to conduct periodic inspections for all stormwater BMPs, which shall be documented in writing. The inspection shall document any maintenance and repair needs, and any discrepancies from the Stormwater System Maintenance Agreement.

Whenever necessary to make an inspection to enforce any of the provision of this Title, or whenever the City has reasonable cause to believe that there exists in any building or upon any premises any condition that may constitute a violation of the provisions of this Title, City personnel may inspect building or premises at all reasonable times provided that:

  1. If the building or premises is occupied, City personnel shall first present proper credentials and request entry.
  2. If the building or premises is unoccupied, City personnel shall first make a reasonable effort to locate the owner or other persons having charge or control of the building or premises and request entry.
  3. The property owner or occupant has the right to refuse entry but, in the event entry is refused, the City may seek a warrant to authorize entry and inspection.

Routine or area inspections shall be based upon such reasonable selection processes as may be deemed necessary to carry out the objectives of this Title, including but not limited to, random sampling and/or sampling in areas with evidence of stormwater pollution, illicit discharges, or similar factors.

Failure to Provide Adequate Maintenance

In the event that the stormwater BMP has not been maintained and/or becomes a danger to public safety or public health, the City shall notify the responsible party personally or by registered or certified mail. The notice shall specify the measures needed to comply with the Stormwater System Maintenance Agreement, and shall specify that the responsible party has 30 days or other time frame mutually agreed to between the City and the responsible party, to complete the necessary measures to comply with the Agreement. If such measures are not completed, then the City may pursue enforcement procedures.

If a responsible person fails or refuses to meet the requirements of an inspection report or the Stormwater System Maintenance Agreement, the City, after 30 days written notice (except, in the event the violation constitutes an immediate danger to public health or public safety, 24-hour notice shall be sufficient), may correct a violation of the design standards or maintenance requirement by performing the necessary work to place the facility in proper working condition. This necessary corrective or maintenance work shall be performed at the owner’s expense.