Running waters need to be envisioned as the arteries of the landscape that connect the dry land with the source of life in the oceans. It is not only that they create the foundation of life, but also stand out for their high diversity and constant change.
- Running water ecosystems belong to the most severely human-impacted habitats on Earth
- Of more than 3,500 species currently threatened worldwide, one-quarter are fish and amphibians.
- In freshwaters, the projected decline in species diversity is about five times greater than that of terrestrial ecosystems. This rate is similar to the historical great extinctions.
- It has been suggested that some 30-35% of all freshwater fish species are already extinct or in serious decline worldwide (Stiassny 1999). Ninety-three percent of these occurred during the last 50 years, indicating extinction of freshwater fish as a serious and accelerating global trend.
- Environmentally insensitive hydropower generation is devastating to the flora and fauna of rivers and streams.
- In urban areas rivers are frequently over-engineered and devastated beyond recognition (e.g. Los Angeles River, Onondaga Creek in Syracuse, NY). Paved river beds, undersized bridges, culverts, storm water facilities, insufficient road drainage and unregulated development in the flood plain are the consequences of inadequate planning that causes billions of dollars in damage annually.
- Lack of standards for river management is also a reason that restoration efforts are ineffective. Of one billion dollars spent annually on river restoration, more than half is unaccounted for and leads to ecological failure.
- Polluted sediments, high mercury levels, caffeine, antibiotics and endocrine disruptors are substances present in rivers that pose serious risks to human health.
- In Northeastern United States thousands of dam relics turn rivers into disconnected warm ponds leading to the extinction of species in rivers and oceans. Dam presence and dam failure is a source of eminent danger to people and causes high and perpetual maintenance efforts.
- The Western and Southern United States, which experienced an era of unlimited growth, face serious water shortages for the expanding populations (especially in desert cities such as Tucson and Las Vegas), which increases the pressure on already dramatically stressed resources.
- In places like Georgia, rather than increasing the efficiency of consumption the response to dramatic water shortage is to construct many new headwater reservoirs at high environmental cost in addition to already existing monumental impoundments.
- It is expected that global change will further increase damage to aquatic biology by higher summer air temperatures, a longer summer season, and lower minimum flows together with more frequent and severe floods. One such extreme event was demonstrated in 2005 by an unprecedented drying of vast, perennially flooded areas of the Amazon River that created massive fish kills and undercut the livelihood of many people.
- Besides the loss of the natural heritage of fish and mussel fauna, or recreational opportunities, we may face the loss of ecological services such as access to clean water, livelihoods, and personal safety.
Despite these dramatic circumstances, the majority of the public, as well as the world decision makers, seem to be unaware of the problems and severe consequences this may have for life on the planet. Our society finds a great comfort believing that what has been accomplished with the introduction of the Clean Water Act (i.e. less polluted waters) secured a sustainable future for our rivers and streams, as well as water supplies. This traditional, very narrow view of aquatic ecology does not capture the core issues such as lack of water, channel alteration, dams or invasive species, which may be as destructive as water pollution.
A myriad of processes (hydrological, hydraulic, geomorphic, sediment transport, thermal, biological and chemical) provide a framework within which ecological and biological functions support life. Establishing a direct link between biological and environmental change turns out to be a particularly difficult engineering task, because it requires not only integration of sciences, but also complex mathematical models capable of describing these functional relationships. Considering the urgency of the problem, as well as the high complexity and variety of research topics related to running water ecosystems, scientists studying them are disproportionately few in numbers and scattered around the world. Moreover, many of these scientists (fluvial geomorphologists, habitat modelers, river ecologists and water quality scientists) are highly specialized and work through different disciplines on aspects of the same ecosystem: rivers. This specialization holds true for professionals: we have water quality specialists, water resources specialists, fish biologists, limnologists, hydraulic engineers and similar. The same is reflected in our laws, which very commonly regulate either flows or water quality as separate entities.