As it prepares for monsoon storms, the Arizona Department of Transportation is asking motorists and their passengers not to toss litter along highways. Why? Because the trash can block drainage grates or wind up in the nearly 60 pump stations that ADOT operates along Phoenix-area freeways.

Pump stations are designed to remove large volumes of water from freeways during storms, with individual pumps able to lift more than 12,000 gallons per minute. They are part of a vast and largely unseen drainage system that can keep freeways open during storms that overwhelm local streets nearby.

Pump stations typically have three to five pumps, driven by powerful engines, to lift storm water from inside the facilities and send it into nearby drainage channels or retention basins.

Motorists can help keep ADOT’s drainage systems operating at full capacity by helping to reduce litter and other debris that can obstruct drainage grates and catch basins that collect runoff, leading to standing water along a freeway.

Another way you can help: Report those you see littering on highways to the ADOT Litter Hotline. All that’s required is providing the vehicle’s license plate number and incident details by calling 1.877.3LITTER or visiting kazb.org. The owner will get a letter noting that someone was reported tossing trash from the vehicle, along with a free litter bag.

ADOT works to clear litter and other debris from pump stations and freeway drainage systems all year long. Piles of litter often have to be collected by hand and hauled out of pump station storage wells. Crews or contractors also use specialized vehicles to vacuum drainage pipes that lead to pump stations.

ADOT technicians also work year round to maintain pump stations and their engines, since storms and runoff are not limited to the summer months.

As monsoon season approaches, ADOT keeps an eye on weather forecasts to prepare for challenges associated with runoff. Localized storms that drop more than 2 inches of rain in an hour can tax any drainage system.

When litter and trash are clogging the system, and water starts to build in travel lanes, ADOT maintenance crews are called away from other duties to deal with blockages. That’s another reason to think before you toss that cup or can out a car window.