Lewis and Clark County Mask Mandate no longer enforced, businesses may still require for service MTN file Lewis and Clark County Mask Mandate no longer enforced, businesses may still require for service By: John Riley and last updated 2021-05-07 20:13:20-04 HELENA â Lewis and Clark Public Health (LCPH) announced Friday the facemask requirement in Lewis and Clark County will no longer be enforced following the signing of Montana House Bill 257 by Governor Greg Gianforte. Businesses can still require customers to wear a mask in their place of business and may deny service to those that do not follow store policies.