PORTLAND -- An increase in medical marijuana gardens in Clackamas County is being welcomed by patients and advocates, while neighbors are alarmed and police are confused about how to handle it.

From January through July, the number of medical marijuana cardholders in the suburban Portland county jumped 23 percent, from 1,207 to 1,481, according to the Department of Human Services Oregon Medical Marijuana Program.

Statewide, officials have seen a similar 23 percent increase, from 15,927 to 19,646.

Even though the figures suggest more people getting the help they need, they raise concerns about more people abusing legal loopholes, more criminals preying on legal growers, and more problems for police officers and courts.

Paul Stanford, founder and director of the national nonprofit Hemp & Cannabis Foundation, says that law enforcement officials and the public are gradually accepting the benefits of medical marijuana.

"Across the board, we're seeing increasing support, and it's so important," Stanford said. "There are so many people who need medicine, but they don't want to break the law."

A marijuana garden that is tended cooperatively by several patients and caregivers who supply marijuana to cardholders who can't grow their own has produced a great deal of surplus marijuana that Stanford provides free and in strictly controlled quantities to patients in Clackamas and other counties.

"Of course, the real solution is to legalize (marijuana)," he said. "But for the most part, it's a positive change in understanding."

Yet the experience of cardholders tends to vary, depending on where they live. In Clackamas County, police contend some cardholders are abusing their rights by growing too much marijuana.

A June report by Oregon's High Intensity Drug Trafficking Area program -- a federal grant program administered by the Office of National Drug Control Policy -- states that the medical marijuana law has been consistently violated and is a major barrier to effective enforcement and prosecution.

From 2006 to 2007, the number of plants police seized jumped from 77 to 1,013 plants growing indoors, according to program figures.

During that same period, the number of outdoor plants seized jumped from 178 to 494, according to Chris Gibson, director of Oregon's High Intensity Drug Trafficking Area program.

Yet advocates such as Stanford say police often seize plants growing legally and that the claim that medical marijuana growers frequently abuse the system is only a campaign to curtail medical marijuana.

David Langshaw, a Milwaukie-area resident, has for four years been a cardholder and grown marijuana for himself and others.

Yet he knows that could mean law enforcement could show up on his doorstep at any time.

"People here have to watch out for that knock-and-talk stuff," he said. "I know my rights, but I worry about all those other people out there who think they have to show everything and answer all those questions."