Marijuana plants grow in a massive tomato greenhouse being renovated to grow pot in Delta, British Columbia, that is operated by Pure Sunfarms, a joint venture between tomato grower Village Farms International, and a licensed medical marijuana producer, Emerald Health Therapeutics.

Ted S. Warren/AP

Denver officials are planning to clear thousands of marijuana convictions prosecuted before its use became legal in the state.

Colorado was among the first states to broadly allow the use and sale of marijuana by adults, but cities elsewhere have led the way on automatic expungement of past misdemeanor marijuana convictions.

A spokeswoman for Mayor Michael Hancock said Tuesday that city officials are still working on a plan to review the low-level convictions deemed eligible, an estimated 10,000 convictions between 2001 and 2013.

Denver officials, including the city attorney, are developing the right approach with the district attorney's office, said Theresa Marchetta, Hancock's spokeswoman. The mayor may issue a sweeping executive order or direct city staff to work with legal authorities and clear the cases individually, she said.

Ashley Kilroy, executive director of the Office of Marijuana Policy, added that the mayor is ready to move on from an era of marijuana prohibition. 

"The mayor feels very strongly that no one should be saddled with low-level marijuana convictions that are no longer illegal," Kilroy said.

She reiterated that planning is still in the early stages, and no timeline to start or complete the process has been set. 

San Francisco, San Diego and Seattle announced their efforts early this year, framing the work as an attempt to repair years of damage on people who found that a misdemeanor conviction could bar them from jobs, housing and financial resources.

Minority and low-income communities have been particularly hurt by those barriers, Hancock said in a statement.

"This is an injustice that needs to be corrected, and we are going to provide a pathway to move on from an era of marijuana prohibition that has impacted the lives of thousands of people," Hancock said in a statement.

Eleven states and the District of Columbia now allow broad marijuana use, and Colorado state lawmakers have begun tackling the issue. California this year passed a law requiring the state Department of Justice to identify marijuana convictions eligible for erasure or reduction and provide lists to local district attorneys.

"It's a long time in coming," said Art Way, director of the Drug Policy Alliance's Colorado office.

Colorado lets people petition courts to remove low-level offenses including possession from their records. But advocates said that can become expensive and time-consuming, and district attorneys can challenge the requests.

CPR News reporter Joella Baumann contributed to this story.