http://www.digitaljournal.com/news/environment/are-legal-marijuana-sales-adversely-affecting-the-environment/article/486670

Are legal marijuana sales adversely affecting the environment?

Posted Feb 25, 2017 by Tim Sandle
The progressive legislation across the U.S. in allowing the legal cultivation of marijuana is helping many people with defined medical conditions. However, the expansion of growing cannabis plants is having an environmental impact.
Cannabis will go on sale in pharmacies within eight months in Uruguay  following the granting of lic...
Cannabis will go on sale in pharmacies within eight months in Uruguay, following the granting of licenses to two companies to grow cannabis for commercial sale
Pablo Porciuncula, AFP/File
The possible extent of environmental damage in relation to cannabis plant cultivation has been called out by researchers from the University of North Carolina at Chapel Hill and Lancaster University in the U.K. The researchers have made a request to U.S. federal agencies to undertake in-depth studies to gather data relating to the environment in relation to legal cultivation farms and facilities.
As to why the researchers are concerned, this relates to the expansion in growing cannabis plants and the impact this is having on local agriculture. Expansion is set to continue, as an example, in Colorado alone, sales revenues have reached $1 billion. This is now on par with grain farming in the state. Interestingly, by 2020 one estimate pitches that country-wide legal marijuana sales will generate more annual revenue than the National Football League.
The focus of the new research is with cannabis being the type of crop that requires high temperatures (25-30 °C for indoor operations) along with other important environmental controls such as a strong light source, highly fertile soil and large volumes of water. A typical cannabis plant requires twice as much water as vines used for cultivating grapes. With this the researchers argue that cannabis cultivation has a major environmental impact due to the relatively high water and energy demands. In addition, the process of cultivation carries the risks of contaminating water, air, and soil.
Conditions are worse with illegal crops. With this the researchers looked at an illegal marijuana plantation in northern California. At this facility the rates of water extraction from streams were deemed to be a significant threat to aquatic ecosystems. Moreover, high levels of growth nutrients and pesticides were traced into the local environment and posed a risk to aquatic wildlife.
A further area that requires research, the scientists argue, is air pollution especially with regard to worker health. There have been no major studies as to the impact on the health of the personnel who tend to cannabis farms. This is likely to increase in importance as farms become larger.
One of the researchers, Dr Ashworth commented: “This is an industry undergoing a historic transition, presenting an historic opportunity to be identified as a progressive, world-leading example of good practice and environmental stewardship."
The research has been published in the journal Environmental Science and Technology. The research study is titled “High Time to Assess the Environmental Impacts of Cannabis Cultivation.”