BALTIMORE (WJZ) — A grade of “C minus” is a long way from the honor roll, but because it represents the water quality in the Inner Harbor, it’s better than expected.

Alex DeMetrick explains–the harbor’s report card shows room for improvement.

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Monday morning’s rain offered graphic proof of what’s flowing into Baltimore’s Inner Harbor. And trash, washed off the streets into storm drains and streams, is just the pollution that’s visible.

Chemicals laid down by air pollution also break free and run off.

“Let’s face it, it’s about pavement and pollution. The more pavement you have, the more pollution you create,”  said Halle Vandergaag, Blue Water Baltimore.

And from numerous water samples taken over the course of last year, the pollution is graded.

The record card gave chlorophyll levels a “D minus,” dissolved oxygen “C minus,” water clarity “D plus,” nitrogen “C minus,” and phosphorus levels “C plus,” averaging out to an overall grade of “C minus.”

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“Which some people think is actually a higher grade than it deserves,” said Adam Lindquist, Waterfront Partnership.

Especially in light of last spring’s huge algae bloom and fish kill, following heavy rains.

But then summer saw drier than normal conditions, which helped the harbor.

“So when we have less rain, we actually have less storm water pollution, which is why this grade is slightly better than it would otherwise be. Although nobody’s claiming a ‘C minus’ is a great grade for the harbor,” Lindquist said.

At this point, weather is calling the shots. It will cost untold millions of dollars to slowdown what’s running off.

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Under state orders to improve storm-water runoff, Baltimore is finalizing the fees it will begin charging residents and businesses to pay for the work.