While we've stopped pollutants from many single sources, such as outlets from factories, we are a far cry from ending pollution from scattered sources like agricultural runoff. Can we turn back the clock to save our fish and ourselves from the toxic contaminants and invasive species we dump in our waters, not to mention preventing the waters from being siphoned to extinction by cities, agriculture and industry?
Contaminated Waterways Even treated sewage can contain hormone-disrupting chemicals from pharmaceuticals and laundry detergents sweep through treatment plants and into rivers, altering the reproductive abilities of fish. Not only can this lower their fertility, but estrogenic chemicals in the flesh and fat of fish caught downstream from waste-treatment facilities can cause human cancer cells to grow in vitro, as announced this April by researchers at the University of Pittsburgh Cancer Institute's Center for Environmental Oncology at the annual meeting of the American Association of Cancer Research.
Now, research into Atlantic salmon shows that hormone-disrupting chemicals may have played a major role in the near extinction of these fish. Salmon larvae exposed for 21 days to low levels of nonylphenol, which can end up in waterways from laundry detergents as well as from industrial discharge, face long-term health effects that threaten their survival.
Of course, banned polychlorinated biphenyls (PCBs) and pesticides remain threats. "Concentrations [of PCBs] are declining, but there are hot spots," notes Sarah Gerould, program coordinator of contaminant biology at the USGS. Children of women who regularly ate PCB-riddled fish from Lake Michigan have suffered from low birth weight and smaller head circumference, traits that can diminish IQ.
One or more pesticides have been detected in 97% of U.S. streams in urban and farming areas, half of all shallow groundwater aquifers in similar areas and 33% of all major aquifers, according to a USGS survey of 51 "hydrological systems" (mostly river basins with the streams, lakes, wetlands and groundwater they encompass) published in February 2007. Five percent of the shallow wells that provide drinking water in urban areas have pesticide concentrations above EPA human-health benchmarks. And long disused organochlorine pesticides (including DDT) still show up in nearly 90% of fish from urban and agricultural areas. Those pesticides found in levels that exceeded human health benefits include: frog-mutating atrazine, the possible human carcinogen cyanazine and the probable human carcinogen dieldrin (now banned) in agricultural areas; and dieldrin and diazinon, associated with lower birth weights, in urban streams. That doesn't boost confidence in swimming in the old water hole or tubing down the rapids. Endangered Species Just keeping water running naturally downstream can require court action. "The Endangered Species Act has been one of the most effective acts to maintain instream flows [water running at adequate levels]," says David Katz, lecturer at the Porter School of Environmental Studies at Tel Aviv University. But instream flows, a vital element of aquatic habitats, aren't always a priority. "[The act] focuses on preserving a species instead of a habitat," he notes. For example, the endangered silver minnow population of the Rio Grande, which reaches the Gulf of Mexico as a trickle because of overextraction, has simply been netted and moved upstream rather than officials restoring water to proper levels.
Still, perhaps there's hope for Washington state's Snake and Columbia rivers. In order to return to their native streams from the Pacific Ocean for spawning, salmon must climb past eight dams, a feat so few finish that Snake River sockeye have ended up on the endangered list. Under pressure from Judge James A. Redden of the Federal District Court in Portland to save the sockeye and other threatened Snake River salmon, local authorities are considering removing the dams to restore the natural flow of the river.
Invasives Non-native animals, plants and diseases pose another threat to waterway ecosystems. Two years ago, fish caught in Lake Ontario were found to have been infected with viral hemorrhagic septicemia (VHS), a virus previously known in European farmed fish. Spreading to other Great Lakes and eastwards, VHS has caused numerous die-offs and now poses a threat to over 40 species of fish, though not to humans. A coalition of 90 environmental groups argues that VHS came to the U.S. via transatlantic freighter, as did zebra mussels, and has called for a ban on ocean vessels in the Great Lakes.
Such quick action is called for. It only took a decade for zebra mussels to spread to all five Great Lakes and to the Mississippi, Tennessee, Hudson and Ohio river basins. Having brought about the near extinction of native unionid clams, the mussels now threaten larval fish and some invertebrates.
An invader of another sort plagues the East Coast: saltwater intrusion in underground aquifers as city wells pull up too much water from the ground. In Florida, Broward and Palm Beach counties are cutting lawn watering to once a week and may have to shut down some wells. Although the problem isn't new, the rising East Coast population is placing added pressure on groundwater systems, forcing some communities to build reverse-osmosis plants to strip the salt out of the water.
Being mindful of these concerns, however, doesn't require avoiding the fun of fishing, boating or swimming. Just check for advisories and leave behind you nothing but clean water and riverbanks.
What You Can Do
• Before you fish, check for advisories at http://map1.epa.gov.
• Don't transport invasives: When boating and fishing, drain live wells, clean vegetation off trailers, remove mussels from hulls and don't dump bait into lakes or rivers. Discard aquarium contents in garbage bags, not in storm drains.
• Don't waste water: Trim your showers to five minutes; for help bring an hourglass shower timer with you ($4.95; www.greenfeet.com). In addition to low-flow showerheads and faucet aerators, fix leaking taps indoors and out, and check your pipes for leaks (see www.thegreenguide.com/green_home).
• When refurbishing, purchase water-conserving appliances. Bathroom: Kohler Escale dual-flush, 0.8 gal./1.6 gallon toilets ($918; www.kohler.com, 800-456-4537); go water-free with a composting toilet such as Envirolet ($1,300 and up; www.envirolet.com, 800-387-5126) or MullToa 60 ($2,213; www.greenhomewellness.com, 613-698-6709). For more, see our Water Saving Appliances Product Report at www.thegreenguide.com/reports.
• Drink tap rather than bottled water, which depletes watersheds. Find out if your water contains any contaminants by asking your local water utility or go to www.epa.gov/safewater/dwinfo.htm. If necessary, filter; see "Three Steps to Clean, Safe Drinking Water."
• Choose non-polluting laundry products (see "Virtuous Cycles") and use organic lawn and garden practices (see "Grass Roots").
Source: National Geographic