Inland waterways are getting trashed. But there’s good news in the days of darkening water, according to a new report that claims at least 15 percent of the world's inland surface water areas are covered by protected areas. The global target for such protected spaces is 17 percent as set out in Aichi Target 11 of the Strategic Plan for Biodiversity 2011-2020 of the Convention on Biological Diversity (CBD).

There’s a big caveat to go along with this news, though. These protected spaces are not distributed evenly across the globe, still falling well below 17 percent in over half of the world's countries, a study from the European Commission Joint Research Centre (JRC) says.

The study, published in PLOS ONE, presents the first global assessment of the percentage of inland open surface waters that are in "protected areas and their transitions in these areas between three classes (permanent water, seasonal water, no water) from 1984 to 2015."

What defines a protected surface water area? According to the JRC, protected areas are areas that are designated and managed to help conserve nature. They are essential for conserving biodiversity and ecosystem services. The study defined inland waters as any stretch of water larger than 30 meters by 30 meters open to the sky, including fresh and saltwater.

These surface waters and wetlands provide vital habitats for many species, and key ecosystem services such as nutrient cycling, primary production, water provisioning, water purification and recreation. Although they are subject to increasingly significant human use and climate pressures, their conservation had not previously been comprehensively studied at the global scale.

Researchers wrote: "We therefore stress the importance of consistently-mapped PA polygons for accurate and comparable reporting of countries’ efforts towards conserving their habitat resources. Data completeness is being improved through systematic efforts by each of the countries providing information to the WDPA, and the constant efforts of UNEP-WCMC to improve this database mean that more accurate assessments will be possible in the future."

The researchers said they anticipate that the 17 percent global protection target for inland surface waters may be met by 2020, but they also called for much stronger efforts to ensure the effective conservation of water bodies within protected areas and the basins in which they are found.

"Changes in water availability (and thus in biodiversity) within protected areas also depend heavily on management outside, particularly extraction of water for agriculture, industry, urbanization, human consumption and dams whose upstream and downstream impacts are felt at the watershed level. Therefore, the changes reported reflect changes in hydrological regimes and water use both inside and outside protected areas."

Improved and integrated management planning of water resources from agriculture to water supply to cities will be required to conserve water habitats and their associated species, even if found within formally designated protected areas.

The study highlights the need to significantly increase efforts to protect these most valuable resources. It also presents a summary of surface water changes in those areas that are currently recorded as "protected."

"Dedicated and much stronger efforts are required to achieve effective conservation of formally protected water resources, given the trends observed and the multiple pressures to which inland waters are exposed in many parts of the world,” the researchers wrote. “The effective conservation of water habitats within protected areas will depend not only on management actions within individual protected areas, but also, and strongly, on the use of water resources in the unprotected landscapes in the basins in which the protected areas are found."

Around 27,000 terrestrial and coastal protected areas were analyzed.