This study examines the relative water demand and potential streamflow impacts of cannabis cultivation, residential use, and non-cannabis agriculture in rural northern California watersheds. While cannabis has received much attention for its potential impact on sensitive aquatic species, the relative contribution to overall water demand in watersheds where cannabis is farmed remains poorly understood. Using spatial and temporal analyses across multiple watersheds, this study assesses how water use for cannabis cultivation compares to other major water users in terms of total demand, spatial distribution, and interannual fluctuations. Cannabis was more rarely the top water user in a given catchment (1.6% of observations) than were residential users (34.6%) or non-cannabis agriculture (29.8%). Cannabis water demand was more seasonal, with greater interannual variability, and more evenly spread among catchments than other water use types. Residential and non-cannabis agriculture had the potential to impair streamflow at annual timescales, while cannabis water use impacts was only evident at the monthly scale. Overall, findings suggest that water demand for residential and non-cannabis agriculture has a greater impact on streamflow than cannabis, but that demands from cannabis may cause additive impacts when all uses are considered. Additionally, the potential for cannabis demand to cause streamflow alteration varied year-to-year, with greater potential for impairment during dry years. Given these dynamics, we recommend adoption of holistic approaches that manage all human water uses to protect sensitive natural resources in cannabis-producing watersheds.

Since the legalization of cannabis in California (USA), unlicensed cultivation has unevenly persisted. Spatial patterns are likely associated with a combination of physical and socio-political factors, though their relative importance remains unexplored. This study examines interannual growth and decline in unlicensed cultivation, the spatial patterns of relocation, redistribution, and clustering, and the relationship between unlicensed cultivation and potential environmental impacts. It uses multi-year spatial data (from 2018-2024) and Generalized Additive Models (GAMs) to conduct landscape-scale analyses of geographic trends, changes in cultivation density, and associations with physical and socio-political characteristics. We found that physical characteristics such as topography, building density, and remoteness were associated with changes in cultivation density, though the direction and magnitude of effects varied across periods. Socio-political factors, including enforcement intensity, fines, bans, and the presence of licensed farms, exhibited complex and sometimes opposing temporal patterns. Licensed farms were the single largest and most consistent predictor of reduced unlicensed cultivation (estimates ranged from -207.79 to -660.06 m2 per km2), suggesting that active participation in permitting regimes fosters stability, norm formation, and deterrence. In contrast, bans and enforcement alone often redistributed cultivation, producing "whack-a-mole" dynamics that increased volatility and, in some cases, environmental exposure. Environmental sensitivity emerged as a significant factor in later periods, with regulated counties showing reductions in cultivation in vulnerable areas, highlighting the potential for permitting systems to mitigate ecological impacts. These findings emphasize the importance of participatory, stable, and well-implemented regulatory frameworks for managing unlicensed cultivation and provide broader insights for formalizing informal or illicit resource use in varied socio-ecological contexts.

This chapter explores the sustainability of hemp by examining prevalent metrics such as water use, nitrogen input, and pesticide requirements, and offers a new metric: cultivation geography. While hemp has been lauded for its lower water and nitrogen needs compared to other crops and its potential for phytoremediation and bioenergy production, the novelty of this crop in emerging regions also highlights the need to understand where hemp is grown within agricultural and natural landscapes. The chapter therefore also presents a case study analyzing the geographic distribution of hemp farms in California, comparing them to THC cannabis and general crops. Based on several geographic impact metrics, hemp is more similar to general agriculture than it is to THC cannabis, yet is still situated in slightly more impact-prone areas than the former. This underscores the importance of mindful geographic expansion to enhance the environmental sustainability of the hemp industry.

California has experienced increasing frequency and intensity of wildfire, with the five largest fires on record since 2018. Over the same period, licensed cannabis production has grown to a high-grossing industry, while remaining an important source of rural livelihood. Importantly, the geography of cannabis production overlaps with high fire hazard areas more than any other crop in the state. We developed and deployed a state-wide survey of licensed outdoor producers to determine direct and indirect impacts of wildfire, as well as how producers have responded to these threats. Quantitative and narrative data were subjected to statistical and thematic analyses, demonstrating key findings around fire-related losses, mitigation tools and techniques, and perceptions of risk. Producers experienced a range of impacts beyond direct burning, including reduced light (affecting grow rates), ash deposition (with impacts on product quality and saleability), and production disruptions. Producer responses to the threat of fire and smoke varied, in part affected by the costs of mitigation, yet some common strategies emerged. However, while most growers reported impacts from fire, these were often outweighed by concerns over other pressures on production and profitability. Our hope is that these findings around the experiences and concerns of California's cannabis producers will inform future research directions and provide the first steps toward policy interventions to better address the challenges of living with wildfire.

The licensed cannabis industry represents one of the top five most economically valued agricultural commodities in California, yet farming largely remains on remote, environmentally sensitive, "marginal" lands. Using mixed methods, this paper examines the determinants of this marginalization, their embedded elaboration, and their relation to historical policy regimes. We used Generalized Additive Models (GAMs) to determine the most important predictors of licensed cannabis industry development since the inception of a statewide licensing program in 2018 and to compare the distribution of licensed cannabis to other forms of rural agriculture, including vineyards and pasture, to understand landscape factors and environmental sensitivity of land uses. We found that a county's median income and the extent of traditional (non-cannabis) agriculture, as measured by the proportion of on-farm (non-cannabis) employment, were both negatively associated with its amount of licensed cannabis agriculture. Ethnographic data suggests that cannabis is often excluded from traditional agricultural areas, through formal local-level bans, restrictive zoning, high "prime" farmland values, and cultural exclusions from other powerful resource users. The resulting relegation to "marginal" lands foments conflicts with amenity land users and environmentalists, even as it partly supports "legacy" cultivators whose farms were established under prior policy regimes. Results suggest that cannabis is more likely to be grown under conditions that introduce regulatory hurdles, including farming on steeper slopes, with natural streams onsite, and without access to large groundwater aquifers for irrigation. Our findings suggest that failure to allow licensed cannabis farming in traditional agriculture regions has led to a self-fulfilling prophecy wherein cannabis cultivation is largely relegated to environmentally sensitive areas where cultivation activity has an elevated tendency for environmental impacts.

Illicit water use for irrigated agriculture can have substantial impacts on the environment and complicates water management decision-making. Water demand for illicit cannabis farming in California has long been considered a threat to watershed health, yet an accounting of cannabis irrigation has remained elusive, thereby impeding effective water policy for the state’s nascent legal cannabis industry. Using data obtained from both permitted and unpermitted cultivation operations, the current study applies novel water-use models to cannabis farms in Northern California to estimate their cumulative and relative water footprints. Our results indicated substantial variation in total water extraction volumes for cannabis farming between watersheds and that most cannabis water use was concentrated in a subset of watersheds, rather than evenly spread across the landscape. Water extraction volumes for unpermitted cannabis were consistently greater than permitted cannabis in the dry season, when streams are most vulnerable to impacts from water diversions. Results from scenario modeling exercises indicated that if all existing unpermitted farms were to become permitted and comply with regulations that prohibit surface water diversions in the dry season, nearly one third (34 of 115) of the study watersheds would experience a 50% reduction in dry season water extraction. In comparison, modest expansion of off-stream storage by all cannabis farms could reduce dry season extraction by 50% or greater in more than three quarters (96 of 115) of study watersheds. Combining diversion limits with enhanced storage could achieve dry season extraction reductions of 50% or greater in 100 of 115 watersheds. Our findings suggest that efforts to address the environmental impacts of unpermitted cultivation should focus on watersheds with greatest water demands and that programs that support expansion of off-stream storage can be helpful for reducing pressures on the environment and facilitating the transition of unpermitted farms to the regulated market.

California (USA) supports the largest legal cannabis market in the world, yet faces increasing risk from wildfire. While anecdotal evidence of impacts to cannabis crops has been documented during recent extreme fire seasons, the economic losses resulting from smoke exposure and other indirect effects (e.g., ash fall, mandatory evacuations, power outages) are not well understood. We conducted an online survey of licensed cannabis farms across the state, reporting wildfire impacts on cannabis crops from 2018 through 2021. We summarized regional variation in reported cannabis crop losses, fit a hierarchical multinomial model to assess the effects of proximity to fire and smoke exposure on crops, and trained a random forest model to make impact predictions for all state-licensed outdoor cannabis farms. We found that cannabis farms experienced wildfire-related crop losses across all cannabis growing regions in 2020, but that northern regions experienced particularly high crop loss across all four study years. We also found that exposure to wildfire smoke was a stronger predictor of reported impacts than proximity to wildfire. The output of our random forest model suggested substantial impacts for the cannabis industry in 2020, with predicted crop losses between 4.54% and 21.61% statewide, and between 9.09% and 42.83% in the northernmost counties. Estimated potential economic losses in 2020 and 2021 were as high as $1.44 billion and $970.04 million, respectively-losses which themselves exceed annual values of many of California's other agricultural commodities. Together our results indicate substantial impacts of wildfire for the California cannabis industry as a whole. We suggest that more attention be given to strategies for mitigating cannabis crop losses from wildfires, especially in light of increasing fire occurrence and severity under climate change.

At the intersection of climate change and rural development, wildfire has emerged as a threat to agriculture in the Western United States. This nexus is particularly problematic for the rapidly developing cannabis industry in California, which includes farms located outside of traditional agricultural zones and within landscapes potentially more prone to wildfire. With the goal of determining whether cannabis is uniquely vulnerable to direct wildfire impacts (in terms of crop loss to burning), we integrated fire hazard severity zone (FHSZ) data, wildfire perimeters, and future burn regime projections in relation to the location and cultivated area of cannabis farming. We then applied descriptive statistics and generalized additive models (GAMs) to compare the location of licensed cannabis farms to other agricultural types in California, including grapes, pasture, and all other general crops combined. We found cannabis farming was located more often in high and very high FHSZs and closer to wildfire perimeters than any other agricultural type. GAM estimates of likelihood of occurrence in high and very high severity zones were highest for cannabis, even after accounting for spatial clustering of farm types, although there was no reliable difference in predicted distances to wildfire. Cannabis more often occurred in projected (from 2020 to 2100) wildfire hotspots than all other agricultural types, with GAM estimates affirming a reliably higher likelihood of cannabis in future hotspots than pasture or general crops. Our findings highlight cannabis' particular vulnerability to wildfire in California and may in fact underestimate wildfire risks given the potential indirect impacts of smoke to crops and farmworkers, which were not evaluated in this study. In light of the sector's growing economic importance in the state, these vulnerabilities should be considered in future cannabis and rural development policies.

As permitted cannabis farming in California continues to expand statewide, including in ecologically sensitive watersheds, an improved understanding of water-use practices is needed. Existing evidence suggests widespread reliance on groundwater wells for cannabis irrigation may result in streamflow depletion, yet our understanding of where and why well use for cannabis is most prevalent is currently limited. Here, we use California state cannabis permitting data to address four important information gaps regarding well use by cannabis farming: (1) the prevalence of groundwater wells as an irrigation source for regulated cannabis farms statewide, (2) the extent to which groundwater use occurs outside of regulated groundwater basins, (3) the most useful predictors of whether a farm will rely on groundwater for irrigation, and (4) the potential well use from cannabis farms that are currently unpermitted. Well use by cannabis farms is common statewide, with percentages in excess of 75% among permitted farms in nine of the 11 top cannabis producing counties. In eight of these 11 counties, more than one quarter of farms using wells are located outside of groundwater basins subject to state groundwater use regulations. We found that cultivation area size was a positive predictor of well use, while annual precipitation and on-farm stream network density were negative predictors, highlighting the influences of water demand and surface water availability. The output of a machine learning model trained with data from permitted farms in Northern California suggests that the majority (60%) of unpermitted farms are likely to use groundwater wells if they follow the same patterns as the regulated industry. Our results suggest that proactive steps be taken to address groundwater use in cannabis regulations in California and call for further research into the effects of groundwater use on streamflow, especially outside of large groundwater basins.

At the intersection of climate change and rural development, wildfire has emerged as a threat to agriculture in the western United States. This nexus is particularly problematic for the rapidly developing cannabis industry in California, which includes farms located outside of traditional agricultural zones and within landscapes potentially more prone to wildfire. Using fire hazard severity metrics, current and historical wildfire perimeter data, and future burn regime projections, we compared the location of licensed cannabis farms in California to other agricultural types, to determine if cannabis is uniquely vulnerable to wildfire. We found that cannabis farming was located closer to wildfire perimeters and more often in high fire hazard severity zones than other agriculture. Over the last 50 years, the distance between cannabis farm locations and fire perimeters decreased significantly, and projected burn regimes for the remainder of the century place cannabis farms at greater risk than other agricultural types. Our findings highlight cannabis’ particular vulnerability to wildfire in California. In light of the sector’s growing importance in the state, and given potentially direct and indirect consequences (e.g., human health risks, socioeconomic impacts), these risks should be considered for the development of future cannabis and rural development policies.

Conventional industrial agriculture in the United States (US) displays a number of recognizable characteristics. Market competition in agriculture, as compared with other sectors, tends to be particularly severe due to the large number of farms, their geographical dispersion, limited options for product differentiation, and the perishability of many crops, which inhibits farmers' ability to choose when to sell. Until 1996, cannabis production in California occurred outside of legal systems. In 1996, California voters approved the Compassionate Use Act (CUA), decriminalizing use and cultivation of cannabis for medical purposes. Fear of detection placed informal limits on farm size, especially on private property where plants could be tied to owners and property seizure and arrest was a real threat. The allowance of medical cannabis cultivation after 1996 affected production dynamics. Legal-medical protections, particularly physician recommendations, made it less risky to cultivate, thus fueling an expansion of the number of cultivators.

The cannabis industry in California is attempting to transition from an international epicenter of unpermitted production to one of the world’s largest legal markets. This formalization process will likely establish new centers of production outside the state’s historical cannabis-producing regions, with implications for local communities and the environment. In this paper we analyzed how cultivation regulations and land characteristics correlate with the geographical development of permitted cannabis production centers in California. We used permit data from the first two years of California’s statewide cannabis regulatory program to document geographic variation in cannabis production and farm characteristics (prevalence of onsite residence, non-landowner farming, county zoning classifications, size of cultivation area). We also used multilevel regression models to analyze whether geospatial characteristics likely to be relevant to environmental regulations (size of parcel, average slope of parcel, density of stream network, land cover type) were associated with farm size (cultivation area) or the likelihood of a parcel being enrolled in the state program. We found that a small number of large farms represented the majority of the permitted cultivation area, with the top 10% of largest farms comprising 60% of total cultivated area statewide. The counties with the most growth in permitted cannabis cultivation area also had the highest rates of tenant (non-landowner) farming and lowest proportions of farms with permanent onsite residency. Farms in these counties were almost exclusively sited on parcels zoned for agriculture. On a statewide scale, parcel size was a reliably positive predictor of enrollment, while average slope and stream network density had reliably negative effects. The same relationships held in predicting cultivation area, together suggesting that the development of the newly-formalized cannabis industry in California may be responsive to environmental regulation. Our results suggest two divergent paths of industry development: one in which smaller farms, which often pre-date legalization, navigate regulations in more remote and rugged regions and a second comprising large farms, which are often newer and operate in areas more favorable to meeting environmental requirements of state and county policies.

There is growing concern over the impacts of cannabis farms on the environment and water resources in particular, yet data on cultivation practices and water use patterns have been limited. Estimates of water use for cannabis cultivation have previously relied on extrapolated values of plant water demand, which do not account for differences in cultivation practices, variation across the growing season, or the role of water storage in altering seasonal extraction patterns. The current study uses data reported by enrollees in California's North Coast Regional Water Quality Control Board Cannabis Program to model how variation in cultivation practices and the use of stored water affect the timing and amount of water extracted from the environment. We found that the supplemental use of stored water resulted in a seasonal pattern of water extraction (water withdrawals from the environment) that was distinct from water demand (water applied to plants). Although water input to storage in the off-season months (November through March) reduced water extraction in the growing season (April through October), farms generally did not have sufficient storage to completely forbear from surface water extraction during the growing season. The most important predictors of storage sufficiency were type of storage infrastructure, type of water source, and farm size, with the likelihood of sufficiency decreasing with increasing cultivation area. As of 2019, state cannabis regulations require forbearance from surface water diversions from April through October. To comply, farms relying on surface water must either develop storage, reduce water demand, or seek alternative water sources, such as groundwater. Our findings indicate that water extraction from farms using groundwater wells generally occurs during the summer dry season and highlight the need to assess their potential impacts to connected surface water in streams. Finally, given that the current study was based on data exclusively from permitted cannabis farms, additional data from unpermitted operations would enhance our overall understanding of cannabis water-use practices and consequences for the environment.

Cannabis is an emerging agricultural frontier, but due to its quasi-legal status its environmental impacts are poorly understood. Where cannabis is irrigated by groundwater, pumping can lead to streamflow depletion in surrounding streams which may impair other water users or aquatic ecosystems. Here, we investigate the impacts of groundwater pumping for cannabis irrigation at the scale of the watershed, the individual well, and the stream segment, and contextualize by comparing with residential groundwater use. Combining mapped cannabis cultivation and residential structure locations with grower reports of irrigation water sources, we develop distributed estimates of groundwater pumping and associated streamflow depletion caused by cannabis and residential users within the Navarro River Watershed in Northern California (USA). An estimated 73% of cannabis cultivation sites and 92% of residential structures in the watershed rely on groundwater, and groundwater abstraction leads to streamflow depletion during late summer when groundwater is a critical source of baseflow to ecologically important streams. However, streamflow depletion caused by cannabis cultivation is dwarfed by the impacts of residential use, which causes >5 times as much streamflow depletion and is concentrated close to ecologically important stream segments. Focusing on cannabis, a small number of wells (<25%) cause a disproportionate amount of depletion (>50%), and significant predictors for impacts of a well are the annual pumping rate, the distance to the closest stream, and the transmissivity between the well and the stream. Streamflow depletion increases nonlinearly when pumping occurs within 1.2 km of streams, and most cannabis and residential groundwater use is within this critical distance. Given the rapid increase in cannabis cultivation, these results indicate that potential streamflow depletion from groundwater irrigation of cannabis is a current and future concern, and will be superimposed on top of significant depletion already occurring due to residential use in the region studied.

Water use by cannabis cultivators represents an emerging threat to surface flows in Northern California's sensitive watersheds. To date, however, no data has been available to formally assess where cannabis sites source their water. This study analyzed data from annual reports, covering the year 2017, submitted by 901 cannabis cultivators enrolled in the Cannabis Waste Discharge Regulatory Program administered by the North Coast Regional Water Quality Control Board. The analysis identified cannabis cultivators' most common sources for water extraction, monthly patterns for each water source and differences between sites compliant and not compliant with the cannabis program. The most commonly reported source of water was wells (58% of sites), with most extraction from wells occurring during the growing season (April through October). Surface water diversions (22% of sites) and spring diversions (16% of sites) were the most common sources after wells, with extractions from these sources distributed much more evenly across the year. Although nearly one-third of noncompliant sites (33%) used wells, this source was more than twice as frequently reported among compliant sites (68%), indicating that wells may become increasingly common as more sites become part of the regulated cannabis industry.