The Clean Water goal captures the degree to which local waters are unpolluted by human-made causes.
The current score indicates that there large opportunities for improvement. This goal scores highest when the contamination level is zero. Reducing the inflow of chemicals, nutrients, human and animal wastes and trash requires remedial actions at every level of society as well as adjustments to behavior on an individual basis.
Overall, the Clean Waters goal has increased modestly since 2012. The global score has, on average, increased by one fifth of a point every year since 2012. This increase is likely due to a decrease in human derived pathogens in waterways (more people have access to improved sanitation facilities), and a decrease in land-based nitrogen input associated with manure and fertilizer application.
The Clean Waters goal includes 4 categories of pollution: chemical pollution (modeled from: vessel pollution, runoff from impervious surfaces, and agricultural pesticide/herbicide use), nutrient pollution (modeled from: Nitrogen from agricultural fertilizer use and manure production), pathogen pollution (estimated from: untreated sewage), and trash pollution (based on observational ocean survey data). For the trash and chemical categories we only have data for one point in time so these categories will influence each country’s score, but they will not capture change over time, even though we know change is occurring. However, the nutrient and pathogen categories are regularly updated and changes in score over time will mostly reflect changes in these pollution categories.
We estimate the amount of nutrient pollution entering the ocean from land based agriculture using a series of fairly complex models and large amounts of data. But, we can get a general idea of what is happening by looking at country inputs of N as reported to FAO. We model N inputs from synthetic fertilizer and manure from agricultural systems. Other inputs that we do not include are from aquaculture and human wastewater.
The amount of N applied to crops in the form of synthetic fertilizer is about 9x greater than the amount of N excreted by animals. However, the proportion of N from each category that ultimately ends up in the ocean will depend on a large number of variables, such as how the manure is treated and used.
For synthetic fertilizers, the past 10 years have witnessed about a 5% increase in fertilizer use (2010/2011 vs. 2018/2019), however, the trend varies dramatically by country. Some of the countries with the largest coastlines and most fertilizer use have actually witnessed a decrease in fertilizer use. For example, mainland China which uses nearly 30% of global fertilizer has decreased their fertilizer use by 8% in the past 10 years. The United States has decreased their fertilizer use by 2.3% over the same period, which actually results in a fairly substantial decrease in global fertilizer use because they account for about 11% of global fertilizer consumption. Germany has decreased their fertilizer use by an impressive 21% during the same period. Of the 166 countries reported by FAO, 55 of them have had a decreasing trend in fertilizer use from 2010-2019.
The input of nitrogen from livestock (including chickens and pigs) has increased over 8% during the past 10 years; however, once again there is much variation among countries. Of the 202 countries reported by FAO, 78 had decreasing inputs of N over the past 10 years. Notable examples include a decrease of over 8% in South Africa and 6% in New Zealand (2010/2011 vs. 2018/2019).
There have been dramatic changes in the number of people that have access to basic sanitation for wastewater. During the past 10 years (2011 to 2020), the global population has increased by about 10%, but the number of people who have access to basic sanitation has increased by nearly 27%. Most, but not all, countries have increased the number of people with access to basic sanitation, but the biggest improvements occurred in India, China, Indonesia, Pakistan, and Brazil.