Water & Cannabis: Swami’s Report

The biggest concern for all farmers in California  right now is, of course, water. It seems that everyone is looking for someone else to blame. Clearly each of us in the exploding human population shares the responsibility.  Since 1970, the population of California has doubled. Today there are 38 million people in our beautiful state, 26 times the 1.45 million residents in 1900. More people simply use more water.

Nonetheless, many want to point the finger at cannabis growers. There have been many estimates of the amount of water cannabis cultivation requires. Who would know better than the growers themselves?  But we never get asked.

The Mendocino Cannabis Policy Council, along with the Emerald Growers Association, has polled numerous cannabis cultivators about their water usage.  From these results we derived, with great help from Casey O’Neill, a formula which is: 1 gallon per 1 day to produce 1 pound of cured cannabis flower buds (1:1:1).

So how much water does cannabis really use?

Our canvassing indicates that most cannabis farmers grow plants that average between 2 and 4 pounds. One eighth acre (50 ft  x 100 ft with 50 cannabis plants) would use 24,000 gal per season ( 8 months = 240 days) to produce fifty 2 pound plants (2 gal per day x 240 days x 50 plants) or 480 gal per plant. A two pound  plant divided into 1/8ths of an oz. yields 256 eighths. Thus the whole garden with 50 plants would  produce 12,800 eighths of an ounce. ( An eighth ounce is a standard retail unit like 1 pound of beef or 1 bottle of wine or 1 can of almonds.)

Each 1/8th ounce then requires 1.875 gallons (24,000 gal/12,800).   It has been widely reported that to produce a pound of beef requires at least 1500 gal of water. Wine uses between 180 to 400 gal per bottle*. Almonds need one gallon per nut or about 100 gal per can, broccoli takes about 5 gal per head, avocados about 75 gal per pound.

But, wait!  The same plant that produces 2 pounds of cured finished flower buds also produces at least 1/2 pound of “little bud” or “smalls” which farmers and dispensaries often donate to needy patients, sell at a steep discount or consume themselves as everyday smoke. It will also produce at least 1/2 pound of “trim shake”. The leftover smalls and the shake can then be processed to make concentrates, edibles, tinctures, salves, oils, etc. All that additional product, all that value added, with no additional water required.

The Calif Dept. of Fish and Wildlife published a report on cannabis growing in Mendocino and Humboldt, highlighting 3 typical valleys.  They concluded that there were about 26,000 plants in Outlet Creek Valley. The implied conclusion, based on an assumption of 6 gal of water per day per plant, was that cannabis was drying up the creeks.

A closer analysis points at a different result.  Using Fish and Wildlife numbers, which most farmers consider too high, 6 gallons a day for the peak growing season of 150 days of summer means 900 gal per plant, which is the same as a 3.75 pound plant for 240 days in our formula (1:1:1), which would require about 2 gallons per one eighth. If there were 400 sungrown plants in an acre (each with 10’ x 10’ canopy in a 200’ x 200’ area), 26,000 plants need 65 acres.

At 900 gal per plant per season, 26,000 plants use 23,400,000 gal per season, or 3,128,342 cubic feet of water  Twenty three million gallons equals 71 acre feet of water, which means that 12 inches of water falling on 71 acres would provide  enough water for the entire 65 acre cannabis crop of Outlet Creek Valley, as long as it is properly  captured  and stored in the rainy season to then be used in the dry months. Even in dry years Mendocino receives about 40 inches of rain, and Outlet Creek Valley covers 103,616 acres, according to Fish and Wildlife.

A questionable assumption in the report is that green house plants, with a canopy of 5’x5’, would use the same amount of water as sungrown plants. Nor does the report address the possibility that some greenhouse crops are “light dep” grows, which would be harvested in August and so use no water at all in the driest months. Missing entirely in the report is any identification of an individual garden’s actual source of water. There is no mention of storage tanks, ponds, springs, wells, or the possibility that water was captured in the rainy months and stored for use in July and August. The unsubstantiated assumption is that all the water came only from Outlet Creek, but the report does not mention the discharge flow of Outlet Creek at all. To demonstrate the effect of increased cannabis acreage they would have to show tables of water discharge at Outlet Creek over a period of 10 to 15 years.  I doubt such data exists.

The Fish and Wildlife report references only the monthly discharge of the Van Duzen River at Bridgeton in Humboldt County. Nevertheless, using their numbers, the flow at Bridgeton at the lowest rate in September (when most growers are actually cutting back on watering, as harvest begins for some strains in September), is 7 cu ft /sec or  4,502,960 gal  per day.  The 26 thousand plants at Outlet Creek use 4,680,000 gal for the whole month! At the driest time, one day’s flow would water all the plants for 30 days, that is 3% of the discharge, not 20%. The smart farmer knows the creeks always have low flow in August and accordingly captures and stores water for the dry season.

If there are 100 valleys in Mendocino County growing 30,000 plants, there would be a total of 3,000,000 plants in the county on 7500 acres needing 7844 acre feet of water which is 2,556,000,000 gal per season. In March, Van Duzen Creek discharges 1,286,560,000 per day; in June, it puts out 321,776,320 per day. Thus, in March, 2 days of flow would water Outlet Creek Valley for the season.  In June it would take 8 days flow for the whole crop.

If one were allowed to grow 400 plants per acre using 900 gal per plant it would need 360,000 gal per acre per season or 1.1 acre feet water per acre per season.

Mendocino County has approximately 16,500 acres of vineyards, using 25,000  gallons of water per acre per week over a 24 week season. This is 600,000 gal x 16,500 acres = 9,900,000,000 gallons or 30,381 acre feet of water, while Mendocino’s  entire cannabis crop uses 7844 acre feet, if there are 100 valleys growing.


The MCPC and the EGA promote responsible organic cultivation in harmony with our environment and  work to educate farmers about best practices.  The Mendocino Cannabis Policy Council has written a ballot initiative for the 2015 county election to have cannabis cultivation classified as agriculture and regulated as such and to establish an advisory board of cannabis issues to be selected by the Board of Supervisors.

Farmers who cultivate this magnificent healing herb conscientiously with love need to be protected as they work to sustain the environment and bring people pure medicine.

We love our mountains as much as the next person.


Swami Chaitanya

Member: MCPC and EGA

*(Vineyards produce about 2 to 10 tons per acre.  2 tons of grapes  produces about 4 barrels of wine which is about 1440 bottles. Water use: I acre grapes (about 2400 plants) uses 25,000-35,000 gallons a week.  6 months = 24 weeks total x 25,000 gal = 600,000 gal/per season / per acre. Vineyard acreage in Calif. has increased by 63% since 1985, from 350,000 acres to 570,000. Which means that their water use has likewise expanded by 63%.)http://www.wineinstitute.org/resources/statistics/article88


http://cetulare.ucanr.edu/files/82035.pdf  for vineyard water usage

http://www.colorado.edu/geography/class_homepages/geog_4501_sum14/Presentations/StExample-NCal%20Spr11.pdf gallons per bottle

http://www.winespectator.com/drvinny/show/id/5350, for bottles per acre,andhttp://www.napavintners.com/harvest/pdf/harvest_valley_facts.pdfhttp://www.huffingtonpost.com/2011/03/22/world-water-day-2011-cost-footprint_n_839189.html




http://bofdata.fire.ca.gov/board_business/binder_materials/2013/october_2013/marijuana_symposium/sbauer_impactsfrommarijuanacultivationboardofforestry.pdf for Outlet Creek 

http://edfc.org/wp-content/uploads/2013/12/MendocinoWebProfile02-11.pdf for Mendo vineyard acreage and 

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