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ENB-4.09 - Sewer and Drainage System User Charges Administrative Rules

Administrative Rule Adopted by Bureau of Environmental Services Pursuant to Rule-Making Authority



1.  Applicability

2.  Purpose

3.  Definitions

4.  Regulatory Authority

5.  Residential Sanitary Sewer Volume Billing Guidelines

6.  Commercial Sanitary Sewer Volume Billing Guidelines

7.  Stormwater Management User Fee Billing Guidelines

Appendix A – Background Information

These are administrative rules for the Bureau of Environmental Services (BES) Sewer and Drainage System User Charge Program. See the Explanatory Information section in Appendix A for applicable code citations, policies, and other information relating to these rules.



1.  Applicability

Sanitary and drainage system user charges must be paid by any person who discharges to the City’s separate sanitary, combined sewer system, separate storm or drainage system.


2.  Purpose

The purpose of these rules is to describe the means used for assessing fair, equitable and appropriate utility bills and to implement Portland City Code (PCC) Section 17.36.050.


3.  Definitions

These rules use terms defined in the PCC Chapter 17.36 and the following:

A.  “Billing period” means a regular period of time for which sewer service charges are billed.

B.  “Class average sewer billing” means an average water usage for residential customers used to bill sewer volume when a winter average use cannot be established. Class average rates may be adjusted due to days of service used, meter failure, the use of a non-metered water source, the use of a water supplier located outside City ofPortland, or if no historical water use data is available.

C.  “Commercial customer” means a ratepayer who owns a property identified in county tax records as a commercial use.

D.  “Metered sewer volume” means the measured actual usage on a water meter used to bill sewer volume for commercial and residential customers during the winter average billing period.

E.  “Minimum sewer volume charge” means that if a residential account uses a 0, 1 or 2 centrum cubic feet during its winter average billing period, a minimum class average volume will be billed but at a lower rate than the class average rate.

F.  “Mixed Use” means a mixture of residential and commercial uses on the same tax lot. The ratepayers for such properties will be billed at the commercial sewer rate unless water usage is metered or billed separately.

G.  “Residential customer” means a ratepayer in possession of property identified in county tax records as residential including single-family and multi-family uses.

H.  “User” means a person who uses property that is connected or discharges to the City sanitary sewer or stormwater management system or receives services from either system.

I.  “Water Unit” means the unit of measurement of water supply consumed by the user, commonly in 100 (or centrum) cubic feet (ccf) units.


4.  Regulatory Authority

Sanitary and drainage system user charges are authorized and governed by the following City authorities:

A.  Section 11-302 of thePortlandCity Charter;

B.  PCC Chapter 3.13 which authorizes creation of administrative rules; and

C.  PCC Sections 17.36.050 and 17.36.080 which authorizes the creation and collection of user charges.


5.  Residential Sanitary Sewer Volume Billing Guidelines

Residential accounts are billed sanitary sewage discharge volume based on the actual water use during the winter billing period and an average winter water use during all non-winter billing periods. The amount of data needed to establish a winter, class, or minimum-use average depends on the billing frequency.

A.  Winter Billing Periods. BES will base winter average usage on water meter-read data during the period of November 1 through April 30 for residential customers. Assigning a winter average will be based on actual meter-read data, or in the absence of actual water meter read data, a class average is used for the following billing frequency as established by the City’s Water Bureau:

1. Monthly Billed Accounts. Winter averages are calculated using water use from the first five billing periods after November 1st.

2. Bi-Monthly Billed Accounts. Winter averages are calculated using water use from the first two billing periods after December 1st.

3. Quarterly Billed Accounts. Winter averages are calculated using water use from the first billed period after February 1st.

B.  Other Billing Periods. For all non-winter billing periods an average use will be assigned to a residential account based on water used during the winter billing period, historical data, or an established class or minimum water use. In all cases actual use will be used to bill sewer volume if lower than the assigned average. Water use is determined by City ofPortland meter reads, contracted meter reads from outside City water districts, or estimated water use based on past use or a class average use.

C.  Class Average. All accounts for which the City does not receive meter reads to verify water use (such as well accounts) are assigned a class average to bill sewer volume.

1.  A class average is assigned for:

a.  New accounts started after the winter billing period; or

b.  Existing accounts that have insufficient meter reads or historical water use data to determine an average winter water use.

2.  The current class average for all residential accounts is 5 ccf per month per dwelling unit.

D.  Minimum Use Average. Accounts billed for 0, 1 or 2 ccf during the metered winter average water use will be assigned the following winter averages based on billing frequency:

1.  Monthly Billed Account. Metered winter average water use of 0 ccf will be assigned 2 ccf minimum use average per billing period. Multi-family monthly billed accounts will be assigned 2 ccf per dwelling unit per billing period.

2.  Bi-Monthly Billed Accounts. Metered winter average water use of 0, 1 or 2 ccf will be assigned 5 ccf minimum use average per billing period. Multi-family bi-monthly billed accounts will be assigned 5 ccf minimum use average per dwelling unit per billing period.

3.  Quarterly Billed Accounts. Metered winter average water use of 0, 1 or 2 ccf will be assigned 7 ccf minimum use average per billing period. Multi-family quarterly billed accounts will be assigned 5 ccf minimum use average per dwelling unit billing period.


6.  Commercial Sanitary Sewer Volume Billing Guidelines

All commercial accounts are billed sanitary sewage discharge volume based on measured or estimated use. Methods for measuring or estimating sewer volume can include effluent meters, process inflow meters or water meters, historical water use, measured discharge, or other methods approved by the City. Metered water not entering the sewer system can be deducted from the determination of sewer volume if it qualifies under one of the following:

A.  Sub-Meters. There is a properly installed internal sub-meter and meter usage reporting procedures are followed according to the City’s Sub-Meter Program guidelines. Sewer credits given through the sub-meter program are applicable to commercial and industrial accounts only. Approved sub-meters installed for monitoring water use or flow must be installed, operated and maintained by the user.

1.  Flow monitoring. All flows generated and entering the sewer system from a source other than water supplied by the City water system must be metered.

2.  Account set-up. All sub-meter credits start once all program requirements have been met by the customer, such as application, meter type/installation, etc. In cases where an applicant can prove that a meter has been installed and has been functioning correctly, and there is sufficient data the Director may allow a one-year back credit.

B.  Estimates. Water provided by the City and not discharged to the sewer system can be estimated if metering is impractical and the method of estimation is based on other verifiable measures approved by the City.

1.  Cooling towers. In cases where it is not feasible to meter all flows from a cooling tower, the Director may allow up to 80% credit of the make-up water instead of metering the tower’s discharge.

C.  Extra-Strength Charges. Commercial and industrial users will be charged an extra-strength charge for excess Biological Oxygen Demand (BOD) or Total Suspended Solids (TSS) in addition to sewer volume charges as detailed in Administrative Rules ENB 4-25 and the annual rate ordinance.


7.  Stormwater Management User Charge Guidelines

All stormwater management user charges are determined by existing impervious area on developed property. Total billed impervious area is determined by actual impervious area measurements or a flat charge based on property use standards. Stormwater drainage system service user charges are a set rate calculated based on 1,000 square feet of impervious area.

A.  Stormwater Drainage System Services User. A stormwater management user charge customer is a person who has the right to possession of a property, and directly or indirectly benefits from stormwater drainage system services provided by the City. Public roads are deemed to be open to the general public, and not in the possession of a person.

B.  Residential Stormwater Charges. Residential stormwater management users are billed a flat rate based on an average impervious area for each housing type determined through County tax records under property description:

1.  Single-family residential         2,400 square feet

2.  2-unit multi-family (duplex)    2,400 square feet

3.  3-unit multi-family                 3,000 square feet

4.  4-unit multi-family                 4,000 square feet

5.  5-unit multi-family or larger    Based on measured impervious area.

C.  Commercial Stormwater Charges. Commercial stormwater charges are based on measured impervious area.


APPENDIX A – Background Information


Sanitary sewer user charges are collected according to the following guiding principles

•  BES maintains and operates a fair and accurate system of billing ratepayers for BES services.

•  BES is responsible for explaining and confirming the accuracy of billing information.

•  BES calculates sanitary sewer and stormwater drainage service rates necessary to fund BES operations using formal cost of service ratemaking principles adopted by City Council in 1977.

Residential Sewer Volume Billing Guidelines

All sewer volume charges billed are based on an average or actual water usage whichever is lower.

Section 4.A. The billing cycle for properties is determined on initial set up of new user water and sewer accounts with the City ofPortland. Accounts are established by the City’s Bureau of Water Works based on the frequency of meter reads and the amount of usage by the site. In general, the majority of users are on a quarterly billing period. Bi-monthly billing periods are used for properties officially outside ofPortland, such as for residences in Rockwood. Monthly billing periods are predominantly used for large customers or for customers requesting monthly billing periods.

The class averages and minimum use averages will be determined in the annual Sewer User Rate.


Signed by Environmental Services Director September 29, 2004.
Filed for inclusion in PPD September 29, 2004.
Amended by Bureau of Environmental Services Director June 13, 2007.
Amended by Director of Bureau of Environmental Services February 26, 2013.