WSET.com - ABC13Know Your Sources by Sean Sublette

I saw an interview with a prominent local businessman recently. He made some assumptions about hydrology and watersheds that are, sadly, quite inaccurate. I began to wonder how many other people hold the same misconceptions.

Being an environmental scientist (atmospheric science is among its many sub-categories), I have a number of colleagues who are professionals in hydrology and watersheds. I sought them out for some fact checking.

The businessman's statements are in quotes.

"Farming is where 90 percent of runoff pollution comes from. Ninety percent of phosphates and other nutrients come from farming."

Admittedly, while farming runoff is substantially high, it is not 90%. Use the Chesapeake Bay as an example. Agriculture is responsible for 60% of the sediment that ends up there. Urban and suburban runoff account for 19%.

However, a closer examination of the type of material going into the Chesapeake tells a different story.

First, agriculture accounts for 45% of the phosphorus going into the Chesapeake. Other human influences account for 52%. These include municipal and industrial wastewater (21%) and urban/suburban runoff (31%).

Second, while agriculture (chemical fertilizers, manure, and agricultural deposition) account for 43% of the nitrogen into the Chesapeake, 56% comes from other human sources: industrial and municipal deposition, industrial and municipal wastewater, developed lands, and septic systems.

Also, the rate of runoff is much higher over developed areas. In some cases, that rate can be 1000 times higher than grassy or forested areas.

 "Artificial ponds or lakes do a better job of collecting runoff than parking lot filters. Experts say lakes and ponds are the best way for nutrients and pollution to settle and absorb into the ground before getting into streams and rivers."

 While artificial ponds, also known as settling basins, are helpful, they are not considered the best option. Managing storm water by simulating natural processes, such as infiltration, is much better at minimizing the transport of pollutants into streams, rivers, and ultimately the Chesapeake.

 "The James River does not even drain into the Chesapeake, it comes in below the Bay, so it's a stretch to say it impacts the Bay."

Consult a map. While most of the water in the Bay originates from the Susquehanna River, to say the James plays no significant role is patently false. Tides oscillate, storms pass, and ocean currents change. All of these mechanisms work to mix materials from the James River throughout the volume of the Bay.

"I think the notion that water off a parking lot is somehow worse [is false]… I don't know the science… we probably go overboard in doing more than we have to do to make sure we don't have a negative impact."

Reflect on that second statement for a moment. "I don't know the science."

Upon observation, water running off of parking lots carries substantially more pollutants than water running over grassy areas. Petroleum immediately comes to mind. Watch the water running into a storm drain sometime, and you will notice the rainbow tint to the moving water. That is leaked oil from motor vehicles.

There are local people, available for consulting, whose profession is environmental science. It is their career and life's work. They have designed tests and run experiments. These experiments are repeatable and produce similar results.

Is it the businessman's responsibility to listen to what a professional scientist, and by extension, the scientific consensus, has to say? If scientists have physical evidence from repeatable experiments, is it appropriate to show some respect for their work, or is it okay to be dismissive and place a derogatory label on them?

That is a question each one of us will have to answer for ourselves.

Look up the Aral Sea in central Asia, or the air pollution in Beijing and Mexico City. Those are not directions I am prepared to go.

I encourage you to do your own research. Spend some time at N.C. State: http://www.soil.ncsu.edu/programs/stormwater/.