A River and Its Water: Reclaiming the Commons - Part 15
15th in a series
“Compared to a star, we are like mayflies, fleeting ephemeral creatures who live out their lives in the course of a single day.”
- Carl Sagan
“The mayfly lives only one day. And sometimes it rains.”
- George Carlin
I remember the first time I waded into a shallow stream with an entomologist many years ago. He scrambled about, looking under rocks, picking up bunches of dead leaves, and examining logs – enthusiastically identifying for me the bugs and other tiny organisms that seemed to be everywhere. He told me that by analyzing the numbers and species of what he called “macroinvertebrates,” he could learn much about the health of the water.
He showed me a mayfly, which lives in larval form for up to a year or more in the streambed, until it becomes an adult and flies off in search of a mate. The life span of an adult female is rarely more than 24 hours, and one species lives fewer than five minutes.
Thankfully, their value to scientists is not tied to their longevity. Mayflies are extremely sensitive to pollution. If a stream has a lot of them in larval form, it’s a sign the water is clean. In fact, he continued, we can evaluate a stream’s health by the relative abundance of different kinds of these microscopic organisms. Some bugs – sow bugs, water striders, beetles – live happily in polluted waters. But others – mayflies, caddisflies, stoneflies – live only in healthy streams.
This was astonishing to me. Clean water? With all those bugs in it? That’s not how I ordinarily drink it.
A stream with no living things in it, he said, is a dead stream.
In states – such as Pennsylvania and West Virginia – where coal mining was a major industry for decades, even centuries, there are a lot of dead streams. The reason is acid mine drainage, the toxic runoff of highly acidic water and heavy metals from abandoned mines, which has left more than 7,000 miles of Pennsylvania’s streams biologically dead. It is, notes the Department of Environmental Protection, “the number one water pollution problem in Pennsylvania.”
“You can walk in it and not even slip,” said Katie Semelsberger, Land Manager of the Altoona, Pennsylvania, Water Authority, about the Kittanning Run, “There is nothing that grows in it.” Kittanning Run meanders across the Allegheny Plateau as it makes its way into the Susquehanna River and eventually Chesapeake Bay, which annually receives over 100 million pounds of acid discharges and sediments that are contaminated with heavy metals from the abandoned mines.
This is one more reminder that a stream is an ecosystem; it is not a pipe. As Robin Vannote and his colleagues noted in the River Continuum Concept, biological communities are continually adjusting to changes in the physical, chemical, and biological conditions as the stream flows from its headwaters to its mouth. One of the astonishing results of this is that a stream can actually clean its own water – if we will let it. This is part of the “ecosystem services” streams provide, services that can save consumers and taxpayers billions of dollars. Just think of the value to all of us of a stream that is teeming with fish, as opposed to a stream that has no fish at all. It's amazing what Mother Nature can do all by herself.