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Man watering Marijuana plants. Source: Huffington Post
Man watering Marijuana plants. Source: Huffington Post

Several months ago, the Torres Martinez tribe announced that they will be growing medical marijuana on tribal lands in the near future.[1] The income from this growing operation could provide the Torres Martinez tribe, and the surrounding area, with a much needed economic boost.[2] However, large-scale growing of the water-intensive marijuana plant may pose an environmental risk in an area already gripped by drought.

While federal drug regulations limit the availability of academic research on marijuana growing and its impacts, literature published by growers[3] estimates that 100-200 gallons of water are needed to produce one pound of marijuana leaves. The table below shows how this compares to other agricultural products common in California.[4]

Agricultural Product Gallons of Water per Pound
Beef 1875
Rice 287
Marijuana (100-200)
Grapes 80
Lettuce 31

From the table, we see that marijuana is relatively water-intensive, not nearly as much as flood-irrigated plants, such as rice, but more than many other common crops. If the Torres Martinez tribe’s marijuana growing operation expands significantly over the next few years, what effect will it have on the limited water resources in the Salton Sea area?

The tribe has set aside 47.2 acres of land for marijuana cultivation, and tribe members have stated in interviews that they plan to pursue an organic, indoor hydroponics system. Based on the production rates of marijuana farming,[5] if the tribe were to use all 47 acres of their growing land for indoor marijuana farming, they could produce 860,000 pounds of marijuana annually, using more than 100 million gallons of water per year. This could have a huge impact on the limited groundwater supplies in the immediate area, but pales in comparison to the overall scale of agriculture in the Imperial Irrigation District (IID).

The IID receives 3.1 million acre-feet per year from the Colorado River[6] and 97% of that water is used for agriculture. That’s almost a million million gallons of water for agriculture every year—or about half of the entire volume of the Salton Sea. Out of those million million gallons of water, approximately 40% eventually ends up draining into the Salton Sea.[7][8] That means that the water the Torres Martinez tribe would need to grow marijuana on their entire growing acreage would account for only 0.01% of the current water use of the IID. How can 100 million gallons of water, especially in a desert, be such a small fraction?

One possible answer is alfalfa. Mainly used as livestock feed, alfalfa requires 160 gallons of water per pound produced,[9] similar to marijuana. While less than 50 acres has been set aside for marijuana by the Torres Martinez tribe, over 140,000 acres of alfalfa[10] are currently growing in the IID. Alfalfa alone accounts for 0.7 million acre-feet of water every year, more than 20% of all the water in the entire IID. While we should not discount the effect of this new marijuana agriculture plan on local water supplies, it provides a good opportunity to step back and look at how much water is used for agriculture, and how that affects the Salton Sea, and California as a whole.

–Written By Katherine Muller

[1] Newkirk, Barrett. “Torres Martinez tribe to grow medical pot on tribal land.” Desert Sun. 12 March 2015. http://www.desertsun.com/story/news/local/2015/03/12/torres-martinez-tribe-grow-medical-pot-tribal-land/70195366/

[2] Armitage, Lynn. “Hitting Pot Jackpot? Tribe Starts Medical Marijuana Cultivation.” Indian Country Today Media Network. 21 April 2015. http://indiancountrytodaymedianetwork.com/2015/04/21/hitting-pot-jackpot-tribe-starts-medical-marijuana-cultivation-160089

[3] O’Neill, Casey. “How Much Water Does it Take to Grow Cannabis?” The Ganjier. 2 July 2015. http://www.theganjier.com/2015/07/02/how-much-water-does-one-marijuana-plant-need-to-grow/

[4] Creelman, Ian. “How Water Intensive Food Choices Impact California’s Drought.” Ecology Global Network. 29 August 2014. http://www.ecology.com/2014/08/29/water-intensive-food-impact-california-drought/

[5] Caulkins, Jonathan P. “Estimated Cost of Production for Legalized Cannabis.” Working Paper. RAND Drug Policy Research Center. July 2010. http://www.rand.org/content/dam/rand/pubs/working_papers/2010/RAND_WR764.pdf

[6] “Water Transportation System.” Imperial Irrigation District. http://www.iid.com/water/water-transportation-system

[7] Salton Sea Authority. “The Salton Sea.” The Salton Sea. San Diego State University. http://www.sci.sdsu.edu/salton/Salton%20Sea%20Description.html

[8] Krantz, Timothy. “Salton Sea, California.” Encyclopedia of Earth. 23 August 2008. http://www.eoearth.org/view/article/155840/

[9] Putnam, Dan. “Strategies for the Improvement of Water-Use Efficient Irrigated Alfalfa Systems.” California Alfalfa and Grain Symposium. 10 December 2012. http://alfalfa.ucdavis.edu/+symposium/proceedings/2012/12-04.pdf

[10] “Crop Rank and Acreage.” Imperial Irrigation District. 2014. http://www.iid.com/home/showdocument?id=9759