Emerald Ash Borer (EAB)

UPDATE (9/5/25): Ward D Ash Tree Removals Begin in the Fall

Starting in September, the City of Watertown Forestry Division will begin managing ash trees in Ward D, where Emerald Ash Borer was first confirmed. Boulevard and public ash trees that are declining, unsafe, or poorly located will be removed, with final decisions made by the Forestry Division. Healthy trees in select areas will be treated during the 2026 treatment window and monitored as part of the City’s management plan.

What Residents Can Expect

Trees marked for removal will be taken down within weeks, and stumps will be cleared within a few months. Some ash trees will be treated to preserve shade and curb appeal. This balanced approach—removing some trees while treating others—will help soften the impact of EAB while giving new trees time to grow. The City’s long-term goal is to reduce ash species so that it makes up around 10% of Watertown’s overall tree canopy over the next 20 years.

Responsibilities

The City manages boulevard and right-of-way ash trees, including deciding which will be removed or treated. If a homeowner already paid to treat a boulevard tree, the City will continue limited treatments of the treated boulevard tree and will reevaluate them every couple years. When boulevard trees are treated, the City covers the cost and the trees will be tagged. Property owners are responsible for ash trees on private property, including their removal or treatment. A licensed arborist can help determine the best option. Boulevard trees are usually located between the sidewalk and the street. Questions can be directed to the Forestry Division at (605) 882-6260.

What is EAB?

Emerald Ash Borer (EAB) is a small green beetle that kills ash trees by blocking water and nutrients. In South Dakota, ash trees make up nearly one-third of public trees, so the impact is significant.

Infested trees typically die within two to four years. Common signs include canopy thinning, bark splitting, D-shaped exit holes, S-shaped tunnels, and heavy woodpecker activity. EAB has already devastated millions of trees across the country and is now present in our community. Watertown Forestry staff confirmed the presence of EAB in June 2025, verified by South Dakota State University.

Why It Matters in Watertown:

Without action, nearly all untreated ash trees will be lost within about ten years. This would mean neighborhoods would lose decades of shade, beauty, and environmental benefits overnight, as well as major removal costs to taxpayers all at once. The City’s long-term goal is to reduce ash species so that it makes up around 10% of Watertown’s overall tree canopy over the next 20 years.

What is the City of Watertown doing about EAB?

The City is taking a balanced approach instead of treating or removing all ash trees at once. What this means:

Boulevard/public ash trees that are unsafe, declining, or poorly located will be removed by the City.
Some healthy boulevard trees will be treated during the May–August treatment window and re-evaluated every couple of years.
If a homeowner has already paid to treat a boulevard tree, the City will continue limited treatment of select boulevard trees and will reevaluate them every couple of years.
Replacement trees will be planted with a more diverse mix of species. Call (605) 882-6260 to get on the replacement list.

This balanced approach protects our community's investment, maintains our quality of life, and ensures a healthier, more diverse urban forest for generations to come.

FAQs

Will we lose all ash trees?

Yes—unless they are treated with insecticide for the lifetime of the tree by a licensed arborist. Untreated ash trees are typically lost within about ten years of detection. In Watertown, some boulevard trees will be treated to preserve shade while new trees grow, but the long-term goal is to reduce ash so that it makes up less than 10% of the overall canopy in 20 years.

Why not remove them all?

If we cut every ash tree at once, neighborhoods would lose decades of shade, beauty, and environmental benefits overnight. Removing trees is also the most expensive part of EAB management. By treating healthy, well-structured trees, we can keep a larger percentage of our community's canopy in place while young replacement trees grow.

Why not treat them all?

Treating trees protects them for many years, but it requires ongoing costs and staff time. Not every ash is healthy enough, safe enough, or well-placed to justify the investment. By focusing treatments on select ash trees, we make sure those dollars provide the greatest benefit to the community.

How does this plan help the community?

By treating some trees and removing others, we keep about half of the ash canopy standing and healthy while new trees grow. This preserves shade and character in our neighborhoods, saves money by spreading out costs, and gives City crews a manageable workload.

What does this mean for me as a resident?

You’ll notice a gradual change instead of all the trees disappearing at once. Streets will stay greener, and the transition will be easier to live with. As replacements are planted, neighborhoods will have a healthier, more diverse canopy for the future.

What Should Property Owners Do?

If you have ash trees on your private property:

Identify them — ash trees have compound leaves with 5–11 leaflets and opposite branching.
Decide whether to remove or treat on private property. Contact a licensed arborist.
Take action early — waiting will increase costs and limit options.

For boulevard trees, no action is required from homeowners. Forestry staff will handle removals and treatments.

View All FAQs

Responsibilities: Boulevard vs. Private Trees

Responsibilities for managing ash trees differ depending on whether the tree is on public property or private property.

Boulevard/Public Trees (City responsibility):
The City makes the decision whether boulevard trees are removed or treated. Homeowners do not need to call or hire an arborist for these trees. If a homeowner has already paid to treat a boulevard tree, the City will continue limited treatment of select boulevard trees and will reevaluate them every couple of years.
Private Property Trees (homeowner responsibility):
Property owners are responsible for the ash trees in their yard. If you want to preserve a private ash tree, you must hire a licensed arborist for treatment. Treatments are only effective if applied May–August and repeated for the lifetime of the tree. If the tree is already in decline, removal is usually the safest option.

Planting New Trees

The City maintains a replacement list for boulevard trees removed from public property. To be added, call (605) 882-6260. Replanting depends on tree availability and budget; it may not happen in the same season as removal.

For trees on private property, residents are encouraged to replant on their own using species from the City’s recommended tree list to help rebuild Watertown’s canopy.

Firewood Reminder

Transporting firewood is one of the fastest ways EAB spreads. Once an area is confirmed to have EAB, firewood movement is restricted. Residents are urged to “buy it where you burn it” and follow all quarantine guidance. Click here for the quarantine guidelines.