More than half of the country’s rivers and streams are in poor biological health, unable to support healthy populations of aquatic insects and other creatures, according to a new nationwide survey released Tuesday. The Environmental Protection Agency sampled nearly 2,000 locations in 2008 and 2009 — from rivers as large as the Mississippi River to streams small enough for wading.

Nearly 200 films from 50 countries will be screened in Washington this month as part of the annual Environmental Film Festival. This year’s theme is rivers, those bodies of water that are simultaneously vital for human survival and vulnerable to human progress.

The salinisation of rivers is a global problem that affects to countries all over the world and it causes a high environmental and economic cost, and poses a high risk to global health.

Groundwater provides drinking water for millions of Americans and is the primary source of water to irrigate cropland in many of the nations most productive agricultural settings. Although the benefits of groundwater development are many, groundwater pumping can reduce the flow of water in connected streams and rivers -- a process called streamflow depletion by wells.

Scientists are now using high-tech solutions to provide real-time forecast of the dangers of river floods caused by climate change and human activities to help avoid disasters. Not all countries are equal in the face of floods.

Ever heard of triclosan? As an antibacterial and antifungal agent, it is used in everything from toothpaste, to soaps, socks and trash bags. While the US Food and Drug Administration, the Environmental Protection Agency, and the European Union all regulate triclosan, the chemical is not monitored and often gets absorbed into sewage sludge after wastewater treatment.

The impacts of global warming are often described in the context of human activities or how it will affect charismatic megafauna and visible landscape features.

With negotiations at an end, WWF Director General Jim Leape today issued the following closing statement about the Rio+20 summit: "This was a conference about life: about future generations; about the forests, oceans, rivers and lakes that we all depend on for our food, water and energy. It was a conference to address the pressing challenge of building a future that can sustain us.

As the climate gets warmer, so do the rivers and lakes that power plants draw their cooling water from. And that is going to make it harder to generate electricity in decades to come, researchers report. In an article in the journal Nature Climate Change, scientists measured temperatures now and projected what they would be at midcentury.

Rivers and streams in the United States are releasing substantially more carbon dioxide into the atmosphere than previously thought, according to researchers publishing their results in the current issue of the journal Nature Geoscience. Their findings could change the way scientists model the movement of carbon among land, water and the atmosphere.