This project evaluated the economic impacts of Eurasian watermilfoil on property values as well as quantified the role of water temperature and other lake characteristics in determining Eurasian watermilfoil abundance.
Background:
Aquatic invasive species (AIS) cause both ecological and economic damage, and climate change influences these effects. This project provided critical information on the impacts of invasive Eurasian watermilfoil (EWM) under both current and future conditions by 1) quantifying the effects of EWM invasion on property values, 2) predicting lake-specific EWM distribution and abundance under current conditions, and 3) assessing the risk of EWM invasion in Minnesota under future climate scenarios.
Findings:
MAISRC researchers quantified the economic impact of EWM invasion by analyzing sales prices for lakefront properties in Minnesota from 1990 to 2019. Their findings indicated that, on average, property values declined by nearly $30,000 (an 11% decrease) following an EWM invasion, though uncertainty in this estimate was high. The effect on property values increased over time; the most significant declines were observed 15–20 years post-invasion (an average decrease of $50,000), compared to a more modest decline of $4,000 within the first 1–10 years.
Using statistical models, researchers linked EWM presence and abundance to lake characteristics, including water temperature, allowing them to estimate both the current risk of invasion and the potential risk under future climate conditions. Their analysis showed that EWM presence and abundance increased with rising water temperatures up to a certain threshold, beyond which very high temperatures negatively affected EWM growth. As temperatures warmed, the risk of EWM invasion was projected to increase for many Minnesota lakes, though in some cases, extreme temperatures could lead to decreased risk. Predictions at the highest temperatures carried greater uncertainty due to extrapolating beyond the range of prior observations.