Colorado recorded its biggest recreational marijuana tax haul yet in April, topping more than $3.5 million in sales and excise taxes, according to numbers released Monday.

In all, the state’s recreational marijuana stores sold more than $22 million worth of product in April, likely boosted by the 4/20 marijuana holiday that brought hundreds of cannabis tourists to town. Overall, though, medical marijuana sales continued to outpace recreational sales, with lower-taxed medical-marijuana stores doing more than $31 million in sales during the month.

So far this year, Colorado has brought in nearly $11 million in sales and excise taxes on recreational marijuana. The total take of recreation and medical marijuana taxes and fees is nearly $18 million.

The new numbers were released on the same day that marijuana activists announced plans to sue the state over recreational pot taxes. According to a copy of the lawsuit sent to the media, the activists argue that the taxes are unconstitutionally high.

Shoppers at recreational marijuana stores pay 12.9 percent in general and special state sales taxes, as well as a 15 percent excise tax that is applied at the wholesale level.

The lawsuit argues those rates violate the constitutional provision voters approved in 2012, which specified that recreational marijuana should be taxed “in a manner similar to alcohol.” The activists say alcohol taxes are much lower.

Attorney Rob Corry, who is representing the activists, said he filed the lawsuit Monday.