Stop population growth

I agree 99 percent with Cliff Terry’s article, “Unless we control population growth, we’re only delaying Bay’s decline,” [April 2000] on the need to “control population growth” in the area. My disagreement is only with one word! In Terry’s “goals,” he lists “Explore acceptable measures to SLOW watershed population growth.” Why not say “STOP” population growth?

Until we as a region — and a nation — are willing to adopt measures to STOP POPULATION GROWTH, some say “stabilize the population,” we will continue to lose the battle to save the Bay.

Terry’s suggested measures are excellent. More people mean more natural environment converted to homes, more sewage, more roads, more schools, more malls, more sediment and other runoff to the Bay, etc etc.

We must face up to the limits to growth — not only in numbers of people but in material consumption — if we are going to leave our grandchildren a functioning Bay with all of its beauty and productivity.

This calls not only for a local population stabilization policy but a NATIONAL policy to stabilize the U.S. population. Currently, the U.S. population policy is essentially for continuous growth, which means continuous population pressure on the Bay region.

I am glad to have people like Cliff Terry raising this issue. We need more individuals supporting the types of measures Cliff Terry proposes.

Barbara D. Hays
Population activist
PA Chapter Sierra Club

If a tree falls in a stream…

In the article, “3 centuries of settlement take toll on water quality” [May 2000], in the section on Forestry, I find it ironic that forestry management is blamed for the lack of an abundance of large woody debris in streams when, as every forester and logger knows, or should know, the Best Management Practices imposed by the State of Maryland require that in streamside management zones, any tree that is felled must be dropped away from the stream and no tops or other large woody debris may be allowed to remain in the stream.

Perhaps the freshwater fisheries scientists in the Department of Natural Resources need to get together with the soil and erosion control experts in the Department of the Environment.

In the Urbanization section, I was equally surprised to read that yellow fever and malaria were considered waterborne diseases spread by raw sewage. While it is true they are transmitted by specific, but different, species of mosquito, they are not normally considered to be waterborne in the sense that cholera can be.

The more common, and far more serious, public heath effects of poor sewerage and sewage treatment, combined with a lack of domestic cleanliness and plumbing, were such once common enteric diseases as typhoid fever and dysentery. They were never as dramatic as, but over the long run much more lethal than, the episodic cholera.

John B. Blake
Frederick County
Forest Conservancy District Board

Shedding light on anecdote…

This is a response to the anecdote that appeared in “Demands of growing population intensify drought’s effect on water table” [Past is Prologue, September 1999].

The clear sky on a sunny day appears blue primarily because of Rayleigh scattering. Particles must be smaller than the wavelength of light to Rayleigh scatter. Most of the clear sky scattering is caused by density fluctuations at the molecular level in air itself.

Gases and liquids are amorphous and, as the molecules move about, their densities fluctuate on the molecular level. These density fluctuations scatter the light.

In crystals, because of the regular, fixed pattern of their atoms, molecules or ions, Raleigh scattering is very weak.

The intensity of Raleigh scattering varies as the inverse fourth power of the wavelength of light. Thus, blue light is scattered about six times more intensely than red light is, giving us the blue sky. Of course, very small particles also scatter blue light more efficiently than red light, which is why the setting sun appears red on a murky day. But most of the light scattered by the sky on a clear day is not from dust motes but from molecular density fluctuating in the atmospheric gases themselves.

Light is scattered in the sky from an air column many tens of miles high. This scattered light will shine directly down a very long tube and maintain its brightness. There is no way that the Rayleigh scattering from directly above can be blocked simply by being down a well and yield a dark, starry sky. I looked up a the blue sky today through a 7-foot long tube and the sky appeared just as bright as without the tube.

Rayleigh scattering is polarized, especially at 90 degrees from the sun. So, if you were wearing Polaroid sunglasses, the sky would appear darker, but not dark enough to see any stars.

But enough of this whining. I enjoy reading“Past is Prologue” in the Bay Journal and appreciate the good work everyone at the EPA Annapolis office are doing to restore the Bay and Maryland’s tidal waters.

George B. Wilmot

Bryans Road, MD

…And, ye author offers a humble retraction

We learn with what tenacity our beliefs persist, Mr. Wilmot!

This winter, grasping your scholarly letter, I carried a ladder down into Middle Valley at my place on Osborn Cove and hung it precariously from the rim of the old dug well casing there. I descended and, hanging on for dear life inches above that icy water, cast my eyes upward. No stars revealed themselves to my gaze, though the sky was a clear cerulean blue. The well was clearly not deep enough.

During the month when I was on emergency assignment at the Patuxent oil spill, an immense cooling tower at the Potomac Electric Power Company’s Chalk Point Power Plant was temporarily decommissioned for maintenance. With permission, I took my camera into that astounding 600-foot tall and cavernous chimney, adjusting the lens to “infinity” and ready to disabuse Mr. Wilmot forever of his mistrust. The battery died and the shutter jammed at that instant. I will still see the stars, says I, and lifted my eyes. George B. Wilmot was absolutely right: I saw only bright blue sky.

I talked to my longtime colleague and EPA scientist Joe Macknis about this and he commented on how often in life our clearest memories can distort the truth. “I remember distinctly,” Macknis said, “making an incredible basketball jump shot during one game and I was so high I was looking down on the hoop. The recollection is so clear! But I know with equal certainty that I never could or will jump that high.”

How careful the presumed historian must be with pitfalls like this throughout mankind’s record on this planet, whether one’s beneath the rim of a basketball hoop, or the rim of a well!

Dr. Kent Mountford