Cannabis Enforcement Unit

Environmental Harm from Cannabis Cultivation

The Water Boards are concerned with the diversion and use of surface water and waste discharges that could harm the waters of the State. The following activities and environmental impacts are associated with cannabis cultivation:

  • Water Supply Issues: Illegal diversions and diverting a stream that harms beneficial uses and/or senior water rights holders.
  • Erosion and Sediment: Poorly maintained and constructed roads and excavation/development of cultivation areas are a major source of sediment pollution from soil erosion. Significant rain events can cause mass sedimentation and large-scale erosion. Sediment increases negative impacts to endangered fish species (salmonids) that cannot tolerate high water levels of suspended solids.
  • Wetland and Riparian Impacts: Draining a wetland, placing fill or excavating water-logged soils from a wetland; removing vegetation from the riparian corridor of a stream; and removing the tree canopy that provides shade to maintain the stream's temperature.
  • Soil Additives: Potting soil and mulch, amendments, fertilizers, and pesticides are stored improperly (outdoors and directly on the ground) or improperly applied, mobilized by runoff and discharged into surface waters.
  • Housekeeping, Trash, and Human Domestic Waste: Large scale cannabis cultivation operations typically generate household garbage, fuel and chemical containers, and other hazardous waste often left at abandoned sites. Human waste that is not properly collected and/or treated can contaminate nearby water supplies with bacteria and other pathogens.
  • Unpermitted Timber Conversion: Cannabis cultivators often do their own clear cutting to develop an open space for their grow sites without obtaining the appropriate permits or considering the environmental impacts. This results in deforestation and increased erosion due to loss of vegetative cover. Trees absorb CO2, removing and storing the carbon while releasing the oxygen back into the air.

Discharge of waste to waters of the State without a permit and/or any diversion and use of water without an appropriate water right may be subject to enforcement and possible penalties.


The Water Boards are developing a regulatory program to protect waters of the State from harmful activities from cannabis cultivation. The program will prohibit waste discharges from agricultural practices, land clearing and grading activities in rural areas and forests. Permits will cover medical marijuana (Proposition 215) grown on private land. Cannabis cultivation on public lands is illegal and may be subject to criminal prosecution. A permit obtained from the Water Boards does not approve or endorse cannabis cultivation.


In October 2015, the Governor signed into law three bills passed by Legislature (Assembly Bills 243 and 266, and Senate Bill 643) that create a licensing and regulatory framework for medical marijuana, collectively referred to as the California Medical Marijuana Regulation and Safety Act (MMRSA).

Best Management Practices for Growers

Program Development

Information for Cannabis Industry

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Coordinating Agencies

The California Water Boards are coordinating with these agencies to ensure that water quality and water supply issues from cannabis cultivation and its related activities are addressed.