-- documents Feed--
-- All of Bhamgov Feed --

Storm Water Credits

Print this page
Text resize increase font size decrease font size
General Methodology

The Storm Water Utility Fee will be apportioned to all properties in the City that contribute storm water into the City’s sewer system, from both surface runoff and underground footing drain inflow.

Runoff Potential & ESWU

The runoff potential for a typical single family residential property is defined as a “standard unit”, called an Equivalent Storm Water Unit (ESWU).  Other types of properties are assigned a multiple of the “standard unit” by dividing their particular runoff potential by the “standard” runoff potential.  The ESWU’s are totaled for all the properties being assessed, and each property’s share of the total is determined by dividing their particular ESWU by the total of the ESWU’s. Information about runoff potential and ESWU determination can be found by following the following links:

Storm Water Utility Fee

The storm water utility fee rate per ESWU will be determined each year for both major drainage districts in the City:  Evergreen Farmington District and South Oakland District.  A particular parcels Storm Water Utility Fee will be the current Storm Water Utility Fee Rate times the ESWU value for that property.  Refer to the Major Drainage District Map for more information.

For 2019, the Storm Water Utility Fee Rates per ESWU on an quarterly basis are:

Evergreen Farmington District (EF): $50.25 per ESWU
South Oakland District (SO): $62.75 per ESWU

Storm Water Credits & Appeals

Property owners will have a means appealing their ESWU determination or for having their storm water utility fee reduced (credits) when they employ methods for reducing the amount of runoff generated by their property that enters the sewer system.  For more information on storm water appeals, follow the link to Storm Water Appeals or go the the Storm Water Appeals Application. For more information on storm water credits, see the information below or view the Storm Water Credit Application.


Storm Water Utility Credits

Certain credits are offered to provide the opportunity for property owner’s to reduce the amount of storm water that enters the sewer system from their property.  Methods for runoff reduction that rely on infiltration will require the property owner to conduct a Percolation Test at the location of the infiltration feature to verify that the existing soils can adequately receive the infiltration. View the Soil Infiltration Testing Protocols in Appendix E.

The following credits are offered for single-family residential (SFR) properties and non-SFR properties, with the associated annual base credit value:

Rain Barrels SFR/Non-SFR $15 2 years
Rain Garden/Bio-Swale SFR/Non-SFR $20* 5 years
Infiltration Trench/Dry Well SFR/Non-SFR $25* 5 years
Cistern SFR/Non-SFR $25* 10 years
Pervious Pavement SFR/Non-SFR $10 (200-300 Sq.Ft.)
$20 (300-400 Sq.Ft.)
$30 (>400 Sq.Ft.)
10 years
Disconnect Footing Drain SFR/Non-SFR $40 10 years
LID Building Measures Non-SFR ESWU reduction N/A
LID Site Measures Non-SFR ESWU reduction N/A
Enhanced Retention Non-SFR ESWU reduction N/A

Those credits marked with an asterisk (*) will be multiplied the relative size of the parcel the improvement makes on the property, provided that the improvement truly captures at least 50% of the impervious area that is draining directly to the sewer system, according to the following schedule:

Classes A & B 1.0
Class C 1.6
Class D 2.4
Class E 3.2
Class F 4.6 

Improvements to non-SFR properties will be calculated on an individual basis, depending on how the improvement impacts their overall runoff factor. The size of the credit will be based on how much impact the measure will have relative to the overall size of the storm water fee being charged for the particular property the credit is being applied for. 

When considering an improvement that would qualify for a credit, it is important to consider how the improvement will be located.  A sample Class B lot layout that shows how a base property with an ESWU of 1.0 can be found under Class B SFR Example.  The drawing shows how the front half of the property typically drains to the street, while the back half drains to the rear yard, where it tends to percolate into the ground (unless the property has been improved with a rear yard drainage system).  Installing rain barrels or a rain garden in the rear year, for example, under these conditions, may not qualify for a credit, as it will not make any meaningful reduction in runoff.

No credits will be issued to single-family residential  (SFR) properties for runoff reduction measures that were already in place prior to January 1, 2017.  The fee values calculated for each Single Family class were based on the entire district’s total runoff as it existed at that time, and cannot be changed retroactively.

Storm Water Credit Application

All credits must be applied for by the property owner, and approved by the City Engineer. Design requirements for each type of credit can be found by following the links to each in the table, as well as criteria for meeting variable credit values. Approved credits will go into effect in the following yearly cycle, and some require periodic renewal. The City has the right to revoke any credits given if the information provided is discovered to be false or if use of the measures are discontinued.  To apply for a Storm Water Credit, complete the Storm Water Credit Application and return it to the Engineering Department, along with Percolation Test results and any supporting documentation, plans, sketches, pictures or calculations.  To view the LID manual, which is Appendix E, follow this link. Applications submitted with incomplete or inaccurate data will not be approved.

Storm Water Credit Values

The value of any credit is to incentivize the effort to reduce runoff, and is not direct compensation for the actual volume of runoff that may or may not be removed from the sewer system in any given period of time or amount of precipitation as a result of the effort.  As more and more property owners employ measures to reduce runoff, the City as a whole will benefit from reduced volumes of storm water that must be treated, and the costs associated with that treatment paid by the City.

ESWU Reductions

Certain non-SFR properties, especially public, institutional, commercial, retail and multi-family parcels will have the opportunity to construct Low Impact Development (LID) measures or enhanced storm water retention on the property that can potentially reduce the Storm Water Utility Fee.  LID measures that reduce the impervious areas on a property or promote infiltration will have a direct impact on the calculation of the ESWU value for the property after re-development.  An example of this for a hypothetical site can be seen at ESWU Reduction Example.  A property owner that elects to use the ESWU reduction for their property will not be eligible for other storm water credits.


General Property Categories

Properties in the City are considered to be part two general categories – single-family residential (SFR) or non-single-family residential.  Non-single-family residential properties include two-family residential, multifamily residential, institutional (public properties, schools and churches), public recreational, commercial, business, office, and parking.

The following maps highlight these general property categories in the City:

SFR Categories

Due to the variability in lot sizes across the City, the single-family residential (SFR) category is divided into six classes based on the total area of the parcel in order to group similarly developed properties together:

Class A 0.125 acres or less
Class B 0.126 to 0.250 acres
Class C 0.251 to 0.500 acres
Class D 0.501 to 0.750 acres
Class E 0.751 to 1.000 acres
Class F 1.001 acres or larger

“Standard Unit”

The most numerous type of property in the City is the Class B SFR, which is considered to be the “standard unit” for determining ESWU’s.  The Class B SFR properties comprise of nearly 50% of the number of parcels in the City.   The runoff potential for the “standard unit” is 4,317 square feet, which is equated to an ESWU value of 1.

ESWU’s for SFR Properties

The ESWU for each of the six lot-area categories for SFR properties is based on the average runoff potential for that category.  For each group, the total impervious surface and pervious surface areas were summed up, and then divided by the number of parcels. Those areas were entered into the runoff potential equation to determine the average runoff potential for each category. The ESWU for each category is calculated by dividing the average runoff potential for each by 4,317 square feet. All single family residential properties in each of the lot-size category are assigned the same ESWU for that category.  The ESWU values for the single-family residential categories are summarized in the following table:

SFR Class A (0.125 acres or less) 3,166 0.7
SFR Class B (0.126 to 0.250 acres) 4,317 1.0
SFR Class C (0.251 to 0.500 acres) 6,714 1.6
SFR Class D (0.501 to 0.750 acres) 10,553 2.4
SFR Class E (0.751 to 1.000 acres) 13,904 3.2
SFR Class F (1.001 acres or larger) 19,744 4.6

All single family residential properties within each of the lot-size categories are assigned the same ESWU for that category.

ESWU’s for Non-SFR Properties

The ESWU for all other, non-SFR properties, is based on the unique runoff potential for each particular property. The impervious surface area and pervious surface area for each of these properties is measured, and the runoff potential is then calculated for each. The runoff potential value is divided by the “standard unit” runoff potential value of 4,317 square feet to calculate the ESWU value for the parcel. An example of this for a hypothetical site can be seen at ESWU Example.

The impervious area measurements for certain properties were verified by analyzing the aerial imagery of the individual parcel instead of relying on the computer-analyzed impervious surface data.  Parcels for verification included all City-owned properties and those with an ESWU over 4.4 as initially determined by the computer-analyzed impervious surface data.

Important Documents and Information on the Storm Water Rate Change


The City of Birmingham maintains a sewer system, which includes the disposal of storm water.  When it rains, water that is not absorbed into the soil runs into the storm drains in the street.  That storm water, once collected in the drains, travels through a vast system of sewer pipes, and is eventually disposed of and purified before being released into the Detroit River by the Detroit Water and Sewer Department (DWSD), currently known as the Great Lakes Water Authority (GLWA).Residents of the City who are connected to the sewer system pay a fee for this service.  In fact, even the City of Birmingham pays into this fund, because the City owns property that is connected into the sewer system.  The City gets a bill from the Water Resource Commission for Oakland County (WRC) for the disposal of this storm water.  In turn, the WRC gets a bill for this stormwater from the former DWSD, now the GLWA.  When the City gets the bill from Oakland County, the City calculates how much each property owner is responsible for, and bills each household that uses the sewer system.

Currently, storm water costs are included in the overall sewer rate charged to all users of the water and sewer system.  The amount a user of the system pays for storm water is based on the amount of water that is consumed based on a water meter.  This system has been in place for a very long time and is the methodology that is used by many similar cities with combined sewer systems throughout the state.  The City is separated into two sewage disposal districts:  George W. Kuhn and the Evergreen-Farmington. For FY 2014-2015 the amount the City was charged for storm water was approximately $1,222,000 for the George W. Kuhn and $1,029,000 for the Evergreen-Farmington districts for a total of $2,251,000.  This cost is then allocated to each user based on the above referenced method.

In 1998, the Michigan Supreme Court decided a case, Bolt v City of Lansing, which dealt with the City of Lansing using its water/sewer bills to raise revenue unrelated to the actual usage. Bolt held that raising revenue through the water/sewer bill was an unconstitutional tax. Bolt also held that cities may use water and sewer bills to pay for the disposal of storm and sanitary sewage, but the charge had to be proportional to the actual usage.   The Bolt case has evolved to now stand as a challenge to municipalities in determining the appropriate methodology for a city to use when apportioning storm water disposal fees to its residents.  The decision resulted in a change in the law as to how cities like Birmingham should divide that fee amongst its residents. One of the factors the Court in Bolt determined is that the storm water disposal fee must be in proportion to the amount of water that enters the sewer system from each parcel or lot in the city.

Bolt v City of Lansing

A property owner challenged Lansing’s newly imposed storm water utility fee, arguing that the fee was a tax levied without voter approval in violation of the Headlee Amendment to the Michigan Constitution. Lansing imposed the storm water fee on virtually all properties in the city to pay for the city’s storm water and sanitary sewer separation project costs as permitted under state statute.

The Michigan Supreme Court ruled that the storm water service charge imposed by Lansing was unconstitutional and void on the basis that it was a tax for which voter approval was required and not a valid use fee.  The Court established three criteria for distinguishing between a fee and a tax:  1) a user fee must serve a regulatory purpose rather than a revenue-raising purpose;  2) a user fee must be proportionate to the necessary costs of the service;  and 3) a user fee must be voluntary – property owners must be able to refuse or limit their use of the commodity or service.  The Court found that the charge failed to satisfy the first and second criteria.

Over time, additional rulings from the Michigan Court of Appeals have helped further define the ruling in the Bolt case as to the specifics of how storm water charges are allocated. What these rulings from the Court have demonstrated is that the billing methodology used by so many communities in the State must be changed as the ability to divide the storm water disposal fee that the cities get charged from the County based on water consumption is no longer an acceptable practice.  As a result, several cities, including Birmingham, have been served with class action lawsuits challenging this methodology resulting from a recent decision by the Michigan Supreme Court.   Other class action lawsuits that have recently been filed on this issue include:

Panzica v City of Jackson 2001
Wolf v City of Ferndale 2014
Wolf v Birmingham 2014
Schroeder v City of Royal Oak 2014
Kish and Bannon v City of Oak Park 2015
v Oakland Township 2015
v City of Dearborn 2016
v City of Detroit 2016
v City of Taylor 2016
v City of Canton 2016
v Westland 2016

City Actions

Going forward, the City is required to implement a new billing methodology beginning January 1, 2017 for storm water utility fees in accordance with a court order.  This new method will be based on several factors such as storm/rainfall rates, topography of each parcel of land in the City, size of each parcel and how much pervious v impervious surface exists on each lot.  To assist in this effort, the City engaged the services of the engineering firm Hubbell, Roth & Clark (HRC) to develop a storm water utility fee apportionment study to develop an acceptable methodology to charge storm water fees.

HRC has been involved in designing and maintaining the City’s water, sewer and storm water systems for several decades and is very familiar with the City’s infrastructure.  The City has been working with HRC for the past several months in the development of this new method.  HRC will present their Storm Water Utility Fee Apportionment Report at the City Commission meeting of October 27th to introduce the proposed change in billing methodology.

In conjunction with the development of the Apportionment Report, the City has also been working with the Michigan Municipal League (MML), as well as, State Representative Mike McCready, in the development of state legislation to address the creation of a storm water utility fee.  Recently, House Bill 5991 was introduced by Representative McCready to the House and was referred to the committee on Local Government.  The City has modeled its ordinance after this legislation and is required to have the new methodology in place by January 1, 2017 to comply with a court order to change from the current methodology.