The Hennepin County Board has awarded more than $250,000 in grants to cities and schools to expand the county's tree canopy and attack the emerald ash borer problem.

The county initially started the program to address the borer problem, which has hit trees in about half the county, said Jen Kullgren, a forester with the county.

The invasive tree pest is projected to kill all of Hennepin County's 1 million ash trees, which make up 15 percent of the tree canopy — defined as those areas shaded by trees.

"It's a slow-moving pest and it's continuing to spread," she said. "Some people are saying it won't be an issue after this harsh winter, but that's just not true."

The grants will be used to establish new canopies as well as remove and replace diseased ash trees. County officials studied which areas were lacking in tree cover, and found Brooklyn Park and north Minneapolis to be at the top of the list. Some of the reasons for the disparity were lower-income residents and higher numbers of rental properties, said Kullgren.

The board awarded a total of 26 grants to cities as small as St. Bonifacius and Tonka Bay, schools and affordable housing developments. A grant of $5,000 was made to the YMCA's Day Camp Christmas Tree in Minnetrista.

Brooklyn Park received the largest grant of $33,462, which it will use to improve the city's existing tree canopy.

In awarding the grants, the County Board prioritized areas with sparse tree cover and higher disparities in air quality, health, income and housing.

A key goal of Hennepin County's canopy program is to manage the ash borer issue.

Minnesota has approximately 1 billion ash trees, more than any other state in the country, according to the state Department of Agriculture. Kullgren said the tree-killing insect was first noticed in St. Paul but reached Hennepin County a short time later.

The pest since has spread to 17 counties in Minnesota and throughout the country, she said.

"We try to encourage grantees to focus on tree diversity so we don't put all of their eggs in one basket," she said.

Hennepin appears to be one of the first counties to offer tree canopy grants. The state had a similar grant program that it ran through the Department of Natural Resources, she said.

The county has an outreach program to promote the tree grants, and encouraged schools to apply so that students become the next stewards of tree canopies, Kullgren said.

New trees provide many benefits to communities, she said. They provide shade for streets, sidewalks and buildings, and that reduces energy use. Trees also decrease health issues like asthma and cardiovascular problems, and studies have shown they have a positive impact on mental stress.

David Chanen • 612-673-4465