Which of the following is not a symptom of watermilfoil encroachment?

Watermilfoil encroachment is a significant ecological issue often associated with various negative impacts on waterways and surrounding properties. The correct answer reflects the fact that an increase in property value is not a symptom of watermilfoil encroachment.

In direct contrast, the presence of invasive species like watermilfoil usually leads to a decrease in property values due to its negative effects on recreational activities and aesthetic appeal. Invasive watermilfoil creates dense mats of vegetation that can obstruct swimming and make boating difficult, which can diminish the attractiveness of waterfront properties to potential buyers.

Additionally, watermilfoil can lead to declining water quality by deteriorating the natural ecosystem of water bodies and disrupting local flora and fauna, further negatively impacting properties adjacent to affected waters. Overall, while the other options directly relate to the detrimental effects of watermilfoil, the assertion that property values would increase in such circumstances does not hold true within the context of its encroachment.