The Santa Clara County Board of Supervisors voted unanimously Tuesday to enact an immediate moratorium on the establishment of medical marijuana dispensaries in unincorporated Santa Clara County, officials said.

Deputy County Executive Sylvia Gallegos said the moratorium is needed in light of San Jose's adoption on June 10 of new controls over marijuana dispensaries, leaving the county a likely place for pot dispensaries or cultivation sites to crop up, Gallegos said.

Board President Mike Wasserman said "the immediate moratorium allows us time to create a permanent ordinance, and at the same time fully analyze the impact on medical access to marijuana for compassionate use."

The board plans to conduct further analysis and weigh the impact that a permanent ban would have on compassionate use of marijuana for illnesses against the adverse effects of marijuana access for adults and children.

This moratorium will allow the County time to prepare zoning ordinance amendments to be presented to the Board at its meeting on August 5.

While there are no marijuana dispensaries or cultivation sites currently licensed by the county, San Jose's new law permits dispensaries to grow marijuana at a single site in the city, in the county or a county that borders Santa Clara County, Gallegos said.

The immediate passage of the moratorium prevents cannabis dispensaries and growing operations from cropping up within the county over the board's July recess, Gallegos said.

According to Gallegos, marijuana should be available for "those 1 percent to 2 percent of Californians who have a serious illness, such as glaucoma, HIV, or cancer."

Research by the county Department of Alcohol and Drugs Services showed that marijuana has a "unique impact on adolescents and young adults because of its effects on memory and executive functioning," Gallegos stated.

The department, in a report released in April, stated that the younger the user of marijuana, the greater the impact on their brain development and regular use can result in a permanent drop of 6 to 8 IQ points.

The county Public Offender office reported finding an association between the growth of unregulated pot dispensaries from a few years ago and a higher percentage of substance-related suspensions in the East Side Union High School District in San Jose.

In the 2011-2012 school term, substance abuse suspensions increased by 106 percent over the year while suspensions at the district's schools in general dropped by more than 28 percent.

While not all of the drug violations were for marijuana, "it was reported anecdotally that the vast majority of these incidents did, in fact, involve marijuana" and schools reported students were coming onto campuses "with baggies, pill bottles, and, in some cases, medical marijuana from the dispensaries," according to Gallegos.

She said that beyond the temporary moratorium, the county's administration has recommended that supervisors prohibit marijuana dispensaries in unincorporated areas.

Since 2009, six marijuana dispensaries opened in unincorporated county lands without land use approvals. Five closed within a month after being contacted by the sheriff's office and county code enforcers, while one dispensary was annexed to San Jose, according to Gallegos.

Deputy District Attorney Patrick Vanier, in a report, said federal and county investigators have discovered "multiple cartel drug trafficking cells operating within the county" and cartel members who were arrested have revealed, "how marijuana cultivation is a significant component to their overall business."

Mexican cartels, including the Sinaloa and Michoacan, oversee cultivations of both indoor and outdoor operations and engage in "human trafficking" by bringing in farm workers from regions they control, according to Vanier.

There has also been an increase in Vietnamese criminal street gangs distributing marijuana in the county, one being the Insane Viet Thugs found in 2010 by state narcotics agents to have operated grow houses and drug rings from San Jose to Vallejo, Vanier reported.

Gallegos referred to findings by the District Attorney's Office that San Jose dispensaries used up to 50 cultivators in California, some run by Mexican drug cartels.

Vanier, in a report on marijuana in the county, said the office had filed charges against 172 illegal marijuana grow operations within the county, 118 of them indoors and mostly in converted homes, from 2011 to 2013.

The 54 outdoor grows, found by the county's Marijuana Eradication Team, were usually located in remote unincorporated areas in foothills outside Milpitas, San Jose, Gilroy, Morgan Hill, Los Gatos, Los Altos, Saratoga and on public lands such as Henry Coe State Park.

Over the last three years, the sheriff's eradication team removed 355,005 marijuana plants and seized 1,838 pounds of illegal processed marijuana bud, mostly from outdoor cultivation sites, Vanier reported.