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Posted at 10:45 AM ET, 05/20/2009

The Scoop on D.C.'s New Wet Weather Fee

Wx and the City

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If you own property in the District, you may be wondering what that new charge is on your water and sewer bill this month. On May 1, the D.C. Water and Sewer Authority (WASA) changed the way it bills sewer charges by lowering the existing sewer rate and adding a new Impervious Surface Area billing charge (PDF). The previous sewer rate was helping to finance the three large underground storage tunnels and other parts of the District's Combined Sewer Overflow Long Term Control Plan. The new impervious surface area fee will do the same, but the charge will now be collected according to the area of impervious surface on each property.

Rain water is just rain water until it hits the ground, and snow is just snow until it melts. Once this water starts moving over the ground, it is labeled "stormwater." Stormwater that is not absorbed by plants or infiltrated into soil runs off over impervious (manmade, non-porous) surfaces that do not easily absorb water. Then, it flows into local waterways, carrying pollutants with it. In older sections of the District, during the majority of D.C. rainstorms, stormwater first mixes with sewage before reaching the rivers.

Keep reading for the inside scoop on D.C.'s new stormwater fee...

Stormwater runoff and combined sewer overflows are major sources of water pollution in Rock Creek and the Anacostia and Potomac Rivers. The federally mandated Long Term Control Plan is a $2.2 billion project that will help reduce the amount of untreated stormwater and combined sewer overflows going into these waterways.

I recently spoke with representatives from WASA to get the scoop on the new charge. Before this month, the CSO fee was included within the sewer rate. Now, they will be separate. The sewer rate will decrease from $3.47 to $3.31 per Ccf (100 cubic feet) and a separate impervious surface charge will be added to the bill, based on the amount of impervious surface area an individual property contains. Properties that have more impervious surface and therefore produce more stormwater runoff will pay more. For example, a building with a large parking lot will be charged more than a building of equivalent size with vegetation. Some customers will even see a decrease in their net sewer charges.

The new charge will be calculated using an Equivalent Resident Unit, or ERU, which represents about 1,000 square feet of impervious surface area. WASA has determined each property's ERUs using GIS survey data recorded over the past few years. The new charge will be $1.24 per ERU - a rate that will increase annually. Businesses will be charged the number of ERUs that equate to each 1,000 square feet of impervious surface area on their properties, but residents will be charged only one ERU for now. All city and federal properties will also be charged, with the exception of public streets.

WASA is still designing the first tunnel. Construction of all three tunnels is due to be completed by 2025. The tunnels are huge, big enough to fit a metro train.

"We expect the CSO reductions to be 96 percent overall in the Anacostia and Potomac rivers and Rock Creek," explains Pamela Mooring of WASA's Office of Public Affairs. "When we started in 2005, the volume of CSOs was approximately 3,254 million gallons per year. As of this year, we have reduced to nearly 2,490 million gallons per year. Once the tunnels are constructed and operational, we expect to still have a ... combined volume of about 138,000,000 gallons per year."

WASA is working with the District Department of the Environment (DDOE) on an incentive program, so that property owners may receive credit for implementing low impact development/environmentally sensitive design projects that retain stormwater, such as green roofs and rain gardens, on their properties. DDOE also charges a stormwater fee that is a separate line item on the water and sewer bill - it is passed through to DDOE, who manages the District's stormwater.

We can't blame the weather for this; precipitation is innocent. But, we can reduce our city's impact by influencing what happens to the rain once it hits the ground. Here are some tips from WASA that anyone living or working in the metro area can do to help reduce stormwater runoff pollution in our waterways:

* Don't throw trash and yard waste in neighborhood storm drains or catch basins -- deposit them in the appropriate cans.
* Don't throw trash on city streets or in alleys.
* Report clogged storm drains or catch basins by calling the D.C. WASA Emergency Line at 202-612-3400.

Thanks to Pamela Mooring, Yvette Downs and Michele Quander-Collins from WASA for providing information for this article.

Related links:

More information and frequently asked questions

Impervious Area Charge Rate Change Calculator
Stormwater and Sewage: The Fate of D.C. Rainfall

By  |  10:45 AM ET, 05/20/2009

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