On March 6, 2023, City Staff presented background on the Emerald Ash Borer (EAB) pest; a review of the City’s 2017 EAB Plan; the current status of EAB and boulevard trees; and three scenarios for moving forward with an updated EAB Plan.  The three scenarios were as follows:

• Scenario #1: Proceed on the City’s current trajectory.
• Scenario #2: Increase treatments and remove infested & untreatable trees.
• Scenario #3: Remove all ash trees.

The pros and cons of each approach were discussed in detail; the primary driver for all scenarios is public safety.  The status of EAB in parks and natural areas, particularly near pedestrian walkways was also discussed.  City Staff was directed to prepare a general assessment of EAB along walkways and natural areas; and to bring back a more aggressive (more tree removal) EAB Plan which also prioritizes public safety.

Once the general approach to moving forward has been decided, many other details will need to be further developed including: the detailed approach to removal and/or treatment; education and outreach to residents and property owners; enforcement of nuisance trees; and a yearly tree sale and reforestation efforts.

Per City Council direction, City Staff proposes a Scenario #4 that is both aggressive and keeps public safety as the focus. While it is unclear exactly how many ash trees are within public ownership (boulevards and parks) without a complete survey, based on recent field visits, we estimate a total number of ash trees that will need to be removed by the city at approximately 4,200. Staff recommends that the city continue to utilize treatments as a management tool and begin an aggressive five-year tree removal plan. We would continue to treat trees that are currently being treated and treat any remaining ash that are treatable over 12” DBH. We propose to treat the 2020 cohort (~250 trees) and up to 1250 more trees if they are treatable. The number of additional treated trees will depend on the level of infestation and condition rating of the trees this spring and summer.

There is an immediate need this year, 2023, to remove trees that are infested in the boulevard, in parks, and along trail corridors. We estimate this would result in the removal of up to 200 trees. Beginning winter 2024, The City would remove, on average, 800 trees a year for the next five years. Removals will happen in winter months to avoid damage to city roads and ensure compliance with federal protection of the Northern Long-eared Bat.

During recent field visits, pest infestation appeared to be consistent in parks with infestation levels in the boulevards with two exceptions: Jim Bell Park Preserve and Pine Knoll Park. The trail corridor in Jim Bell had the highest concentration of heavily infested trees, which will be a part of the priority hazard mitigation this year. Monitoring by city staff will be instrumental in identifying infested ash to prioritize removals.

The city is transitioning from “generally infested” to “heavily infested” as pest population is coming to a peak and will soon affect most ash trees in the city regardless of location. Staff recently attended the Shade Tree Short Course, a conference focused on urban forestry with staff from surrounding municipalities and local agencies in attendance. Engaging with staff from surrounding communities, and attending sessions focusing on EAB, confirmed staff’s sense of urgency as we are behind in managing this pest. Most communities have been actively removing or treating since the discovery of the pest in Minnesota many years ago.

A summary of expected costs to follow Scenario #4 is as follows:

Prices are based on assumptions of number of treatable trees for years 2023, 2024 and 2025. Removal costs assume 800 tree removals a year, on average, starting in 2024. We assumed an average removal cost of $1000 per tree. The figure of $1000 per tree is averaging the lower costs of trail corridor trees that won’t need stumps removed and brush can be left or processed on site. Removing 800 trees a year is very aggressive compared to other municipalities.

Staff suggests Solid Waste fund balance be used for the 2023 costs; and that a funding approach for 2024-2028 be developed. 

Approve Emerald Ash Borer Plan