Runoff

sewer 1

“A little water clears us of this deed.”

~ Lady Macbeth

With the current loosening of restrictions on water quality and pollution discharges to streams and rivers, it’s worth thinking about what clean water actually means. We should all be familiar with the hydrologic cycle, where water evaporates into the atmosphere, condenses and falls to the earth as precipitation, collects in rivulets and flows into the groundwater or surface water to ultimately evaporate again.

The precipitation can collect air pollution particles out of the air as it condenses and falls, and when water collects it can dissolve or pick up all kinds of materials in or on the ground. In addition, we intentionally and unintentionally discharge pollutants through our storm water and sewer discharges.

Natural vegetation and soils can intercept pollutants in the water, providing a natural cleansing of the flow. However, too much contamination can overwhelm the natural systems and result in the accumulation and further spread of the contamination.

In the U.S., in the late ‘60’s and early ‘70’s, we became conscious that water pollution needed to be addressed. (Public opinion on this was exacerbated by the Cuyahoga River catching on fire due to industrial pollution.) Far-reaching anti-pollution laws and regulations were passed to “restore and maintain the chemical, physical, and biological integrity of the nation’s waters,” and significant federal funding was provided to state and local governments to clean up their discharges.

Significant progress has been made in eliminating pollution from direct discharges and runoff over the last 40 years. We understood the relationship between clean surface waters and groundwaters and our own drinking water. Of course, if you dump sewage into a stream, you’re only passing it off to a downstream water user. While we in Colorado enjoy relatively unused water (except for some mining discharges), downstream users get to drink our leavings, diluted by other flows. (Note the apocryphal Coors motto: This ain’t no downstream beer!)

However, continued progress is not assured, as noted by reporter Jeremy Hance,  “On 3 August 2014, residents of Toledo, Ohio, woke to the news that overnight their water supply had become toxic. They were advised not only to avoid drinking the water, but also touching it — no showers, no baths, not even hand-washing … Boiling the water would only increase its toxicity while drinking it could cause “abnormal liver function, diarrhoea, vomiting, nausea, numbness or dizziness” Lake Erie, the source of Toledo’s water, is contaminated by discharges and runoff causing algae blooms. “The causes of the blooms vary, and in some cases are never known, but in many parts of the world they are being increasingly linked to climate change and industrialised agriculture.”

Progress has also been made in cleaning up our drinking water through treatment for organics, chemicals and naturally-occurring minerals. Water treatment plants also provide disinfection of the water supply to eliminate bacterial and some viral organisms, many of which pass through routine sewage treatment systems.

However, contamination can creep into the water supply after treatment, as shown by the Flint, Michigan problems with lead. Old water systems used lead piping, and in many places those components are still in place. A change in the source water, resulting in a different source water chemical make-up, resulted in lead in the old pipes being dissolved into the drinking water. The lead levels in the ‘treated’ water were significant and major disruption and health issues resulted.

We have made significant strides in combating direct discharges of pollutants to our waterways from municipal sewage and industries, but attention to indirect discharges is still required, as shown by the Lake Erie situation. Janet Marinelli reports, “More than 100,000 miles of U.S. rivers and streams are polluted by nitrogen and phosphorus, much of it from agricultural runoff.”

Stabilizing the stream sides with vegetation mitigates the erosion of soils and vegetation helps to remove contaminants and sediment from the runoff.

Marinelli explains, “As storm water runs off of farmland, it can wash away not only pesticides and soil but also nutrients such as nitrogen and phosphorus from commercial fertilizers and manure. These pollutants enter upstream waters, such as Beaver Run, and end up in larger water bodies like the Delaware, degrading water quality by promoting algal blooms that can harm aquatic species by depriving them of oxygen. They also create toxins and compounds in surface and groundwater supplies that can be harmful to human health.”

“According to the Environmental Protection Agency (EPA), more than 100,000 miles of U.S. rivers and streams have poor water quality because of nitrogen and phosphorus pollution, which the agency calls ‘one of America’s most widespread, costly, and challenging environmental problems.’”

However, buffering watersheds from agricultural runoff is a practical and relatively easily implemented option. “In Pennsylvania, an innovative program is showing farmers how to plant cash crops in buffer zones to help stabilize stream banks and clean up waterways.”

Marinelli notes that working buffers in Pennsylvania consist of three zones:

  • A strip of native woodland that stabilizes the bank with tree roots and enhances wildlife habitat.
  • Trees and shrubs that can tolerate periodic flooding and also provide products for profit or personal use. For example, black walnut, American hazelnut, pawpaw, American persimmon, and common elderberry.
  • A zone adjacent to crop fields or grazing lands, where mechanical harvesting is allowed. Candidate crops require slightly drier soils, such as blueberry and black raspberry, as well as decorative “woody florals” such as curly willow, wild hydrangea, pussy willow, and winterberry holly.

“In addition to edible fruits, nuts, mushrooms, and cut stems for the floral trade, advocates say, working buffers with beehives can produce income from honey. Depending on the location, working buffers can also yield high-value medicinal plants like ginseng and black cohosh. Mulberries and other trees can provide fodder for livestock, an attraction for dairy farmers.”

The perfect solution is, of course to quit putting pollutants on the ground, into the air or into the water in the first place and use our laws and regulations to keep everyone safe and healthy. What a thought!

Additional information:

Jeremy Hance, Lethal Algae Blooms — An Ecosystem Out Of Balance, January 4, 2020, The Guardian

Janet Marinelli , A Movement Grows to Help Farmers Reduce Pollution and Turn a Profit, March 12, 2020, YaleEnvironment360

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