Tag Archives: dust

Water Policy in California: Six Key Takeaways from the State Water Board’s New Cannabis Cultivation Policy

By Amy Steinfeld
No Comments

Cannabis is the most highly regulated crop in California, and the state just added another layer of regulation. This article breaks down the State Water Resources Control Board’s (SWRCB) recently updated Cannabis Cultivation Policy – Principles and Guidelines for Cannabis Cultivation (“Policy”) into six key takeaways.1 These guidelines impose new rules on cannabis cultivation activities that have the potential to impact a watercourse (stream, creek, river or lake). Most of these rules apply to cultivation of sun-grown cannabis, which is currently allowed in some form in 12 counties. Compliance with these new requirements will be implemented through the CalCannabis Cultivation Licensing Program.

  1. When developing farmland, hillsides should be avoided and erosion must be controlled.

The Policy provides specific rules for growing pot on undisturbed land. To prevent erosion, numerous limitations are placed on earthmoving and activities in sensitive areas, and cultivators are not allowed to grade hillsides that exceed a 50% slope.2

Cultivation prepping activities must minimize grading, dust, soil disturbance, erosion, and impacts on habitat, especially during the winter season.3 No vehicles or heavy equipment may be used within a riparian setback4 or watercourse,5 and cultivators must avoid damaging native riparian vegetation6 and oak woodlands.7 All farm equipment, fuel, and hazardous materials must be carefully stored away from creeks and sensitive habitat.8 The Policy also governs road construction.9

  1. Cultivators should avoid work in or near a surface waterbody.10

If a cultivator’s activities impact a river, stream, or lake, they must consult with the California Department of Fish and Wildlife (CDFW).11 Cultivators must maintain minimum riparian setbacks for all cannabis activities, including grading and ancillary farm facilities. Before grading land, a biologist must identify any sensitive flora or fauna, and if any is located, consult with CDFW and provide a report to the Regional Board.12 No irrigation runoff, tailwater, chemicals or plant waste can be discharged to a waterbody.13 Diversion facilities for the irrigation of cannabis may not block fish passage, upstream or downstream, and must be fitted with a CDFW-approved fish screen; new facilities are subject to all applicable permits and approvals.

  1. During the dry season, cultivators may not use surface water.

The use of surface water supplies in California requires a valid water right and the use of water for cannabis cultivation is no different.14 Anyone seeking to appropriate “water flowing in a known and defined channel” or from a watercourse must apply to the SWRCB and obtain a permit or license.15 Alternatively, a landowner whose property is adjacent to a watercourse may have a riparian right to divert the water for use on her land. Riparian users do not need permission from the SWRCB to divert water, but they must report water use annually.16

The biggest obstacle that growers face under this Policy is that they cannot divert anysurface water during the dry season—the growing season (April 1 through Oct. 31). It should be noted:

  • The seasonal prohibition of surface water diversion applies regardless of the nature of the water right or what has been historically used to irrigate other crops.
  • During the dry period, cultivators may only irrigate using stored water (see no. 5 below) or groundwater.
  • It remains to be seen whether a legal challenge will be brought against the state for their draconian prohibitions on irrigating cannabis during the six-month growing season. Because this prohibition applies to all watersheds in California, singles out one low-water use crop, and ignores established water rights, it is overly broad and may constitute a constitutional “taking” of property rights.
  1. During the wet season, surface water diversions must be monitored closely.

Cannabis-specific restrictions also apply during the wet season. From Nov. 1 to March 31, cultivators must comply with instream flow requirements and check in with the state daily. All surface water diversions for cannabis are subject to “Numeric and Narrative Instream Flow Requirements,” to protect flows needed for fish migration and spawning. To ensure diversions do not adversely impact fish flows, cultivators must also “maintain a minimum bypass of at least 50% of the streamflow.”17,18

While valid appropriative right holders may divert more than 10 gal./min. for cannabis irrigation during the wet season, riparian right holders are not allowed to exceed that diversion rate.19 All cultivators (including small diverters <10 acre-feet (“AF”)/yr) are required to employ water-saving irrigation methods, install measuring devices to track diversions daily, and maintain records on-site for at least five years.20 Cultivators must inspect and repair their water delivery system for leaks monthly,21 and inspect sprinklers and mainlines weekly to prevent runoff.22

  1. Cannabis cultivators may obtain a new water storage right for use during the dry season.

To address dry season irrigation limitations, cultivators are urged to store water offstream during the wet season, including rainwater, for dry season use. Growers may not rely on onstreamstorage reservoirs, except if they have an existing permitted reservoir in place prior to Oct. 31, 2017.23 Alternatively, small growers (storage is capped at 6.6 AF/yr) may benefit from the new Cannabis SIUR Program, an expedited process for cultivators who divert from a surface water source to develop and install storage offstream. Only diverters with a valid water right that allows for diversion to storage between Nov. 1 and March 31 qualify.

  1. Groundwater is less regulated, but cultivators should avoid drilling or using wells near waterbodies.

Groundwater is generally the recommended water supply for cannabis because, unlike surface water, it may be used during the dry season and is not subject to many of the restrictions listed above. It should be noted however:

  • Many groundwater basins are now governed by California’s Sustainable Groundwater Management Act (“SGMA”), which requires water agencies to halt overdraft and restore balanced levels of groundwater pumping from certain basins. Thus, SGMA may result in future pumping cutbacks or pumping assessments.
  • In some counties, moratoriums and restrictions on drilling new wells are on the rise.
  • Under this Policy, the state may step in to restrict groundwater pumping in the dry season in watersheds where there are large numbers of cannabis groundwater, wells located close to streams, and areas of high surface water-groundwater connectivity.24

In short, groundwater pumpers are at risk of cutback if the state deems it necessary to maintain nearby creek flows.Noncompliance can bring lofty fines, revocation of a grower’s cultivation license, or prosecution

Final Takeaways

This cannabis policy presents one of California’s most complex regulatory schemes to date. Before investing in a property, one must understand this Policy and have a robust understanding of the water rights and hydrology associated with the cultivation site. Growers looking to reduce permitting time and costs should invest in relatively flat, historically cultivated land with existing wells and ample groundwater supplies, or alternatively, grow indoors.

This article attempts to synthesize the maze of water supply and water quality regulations that make compliance exceedingly difficult; more detailed information can be found here. Noncompliance can bring lofty fines, revocation of a grower’s cultivation license, or prosecution. Growers are encouraged to contact a hydrologist and water lawyer before making major investments and to designate a water compliance officer to monitor and track all water diversions and water used for irrigation. Growers should also consult with their local jurisdiction regarding water use restrictions and stream setbacks before moving any dirt or planting cannabis.


  1. The Policy is available at: https://www.waterboards.ca.gov/water_issues/programs/cannabis/cannabis_policy.html (will go into effect on or before April 16, 2019.)
  2. Policy, Appendix A, Section 2, Term 4. The Policy defines “Qualified Professional” as a: California-Licensed Professional Geologist, including Certified Hydrogeologist and Certified Engineering Geologist, California-Licensed Geotechnical Engineer, and Professional Hydrologist. (Policy, Definition 72, p. 11.)
  3. Policy, Appendix A, Section 2, Terms 4 and 10.
  4. Policy, Appendix A, Section 2, Term 3.
  5. Policy, Appendix A, Section 2, Term 40.
  6. Policy, Appendix A, Section 2, Term 33.
  7. Policy, Appendix A, Section 2, Term 34.
  8. Policy, Appendix A, Section 2, Term 7.
  9. Policy, Appendix A, Section 2, Terms 15 to 29.
  10. Policy, Appendix A, Section 1, Term No. 41.
  11. Policy, Appendix A, Section 1, Term No. 3; see also 1602.
  12. Policy, Appendix A, Section 1, Term No. 10.
  13. Policy, Appendix A, Section 1, Term No. 326.
  14. Policy, Appendix A, Section 2, Term 69.
  15. Wat. Code §1225; See alsoWat. Code §1201 [providing that the state shall have jurisdiction over, “[a]ll water flowing in any natural channel” except water that is appropriated or being used for beneficial purpose upon land riparian to the channel.”]
  16. Wat. Code §§ 5100–02.
  17. Policy, p. 12.
  18. Policy, Attachment A, pp. 60, 63.
  19. Policy, Section 2, Term 78.
  20. Policy, Section 2, Term 82.
  21. Policy, Section 2, Term 95.
  22. Policy, Section 2, Term 99.
  23. Policy, Section 2, Term 79.
  24. Policy, p. 11.
photo of outdoor grow operation

How to Reduce Mold & Contaminants in Indoor, Greenhouse and Outdoor Grows

By Ketch DeGabrielle
No Comments
photo of outdoor grow operation

Controlling your grow environment doesn’t start when you germinate your first seeds, it starts before you build your grow. There are steps you can take that will have a significant impact on mold growth and contamination, and these will vary based on the grow environment you choose.

Below is a roadmap to where each grow environment stands in terms of mold and contamination risk, and simple steps you can take to mitigate these factors.


The benefits of an outdoor grow are significant – using natural sunlight to grow plants is both inexpensive and environmentally sound. However, it allows the least amount of control and makes plants susceptible to weather conditions and outdoor contaminants including dust, wind, rain and insects. Depending on humidity and precipitation levels, mold can be a big issue as well.

Outdoor growing has obvious benefits, such as natural sunlight, but may also require extra steps to prevent contamination

When selecting an outdoor area for a cannabis farm, there are two important factors to consider: location and neighboring farmland. Geographical environments and sub-climates vary and once you have purchased land, you are committed, so be sure to consider these factors prior to purchase.

While arid desert climates have abundant sunlight and long growing seasons, flat, dry lands are subject to dust-storms, flash floods and exceedingly high winds that can damage crops. Conversely, more protected areas often have high humidity and rainfall late in the season, which can create huge issues with bud rot and mold. Neighboring farms also have an impact on your grow, so be sure to find out what they cultivate, what they spray, their harvest schedule and how they run their operation. Large farming equipment kicks up a lot of contaminant-laden dust and can damage crops by displacing insects to your farm if they harvest before you. Pesticide drift is also a major issue as even tiny amounts from a neighbor’s farm can cause your crops to fail testing, depending on what state you are in.

With outdoor grow environments always at the mercy of Mother Nature, any cultivator is wise to control contamination potential on the ground. Cover soil and protect your crop by planting cover crops and laying plastic mulch on as much ground as reasonable. In many cases it makes sense to irrigate uncultivated parts of your farm just to keep dust down.


Greenhouses are the future of cannabis cultivation. They allow growers to capture the full spectrum and power of the sun while lessening environmental impact and operating expenses, while still being able to precisely control the environment to grow great cannabis. With recent advancements in greenhouse technology such as automated control systems, positive pressure, geothermal heating or cooling and LED supplemental lighting, greenhouses are the future. However, older or economy greenhouses that take in unfiltered air from outside still have a medium amount of mold and contamination risk.

A greenhouse grow facility

Before building your greenhouse, study the area while taking into account climate, weather conditions and sun exposure. Excessively windy areas can blow in contaminants, and extremely hot climates make cooling the greenhouse interior a challenging and costly endeavor.

There are several simple operational tactics to reduce contaminants in a greenhouse. Add a thrip screen to keep insects out, thoroughly clean pad walls with an oxidizing agent after each cycle, and keep plants at least 10 feet from pad walls. Plan to flip the entire greenhouse at once so that you can clean the greenhouse top to bottom before your next crop. A continuous harvest in your greenhouse allows contaminants to jump from one plant to the next and reduces the ability to control your environment and eliminate problems at the end of a cycle. Lastly, open shade curtains slowly in the morning. This prevents temperature inversion and condensation, which can cause water drops to fall from the ceiling and transfer contaminants onto plants below.


An indoor environment offers ultimate control to any grow operation. Cultivators can grow high-quality cannabis with the smallest potential for yeast and mold growth. Unfortunately, indoor environments are extremely expensive, inefficient and environmentally costly.

An indoor cannabis operation set up (Image: Tall Trees LED Company)

With indoor grow environments, keeping mold and contaminants at bay comes down to following a regimented plan that keeps all grow aspects clean and in order. To keep your grow environment clean, change HVAC filters multiple times a month. It’s also important to install HEPA filters and UV lights in HVAC systems to further reduce contamination threats. Clearly mark air returns if they are near the ground and keep those areas free of clutter. They are the lungs of your grow. Also, stop using brooms in the grow space. They stir up a lot of contaminants that have settled to the floor. Instead, use HEPA filter backpack vacuums or install a central vacuum system. Set up a “dirty room” for anything messy on a separate HVAC system, and be sure to thoroughly clean pots after every harvest cycle.

Learn more about reducing mold and contaminants in an indoor or greenhouse grow in another article from our series: 10 Ways to Reduce Mold in Your Grow.