With the forecast for sun and temperatures in the 80s or even 90s through late next week, the Minneapolis Park and Recreation Board (MPRB) that Minneapolis trees and lakes will be affected.
If you can, please water street trees near your residence; and know that algae growth is likely on many city lakes.
Helping thirsty street trees
Hot, dry weather can stress trees. This is especially true for trees under five years old, which includes many new or recently planted trees on city boulevards (the land between the sidewalk and the street).
MPRB plants thousands of trees every spring, and asks Minneapolis residents to remember that trees need water any time local rainfall is less than an inch in a week – from spring through summer and fall.
With an already dry spring, staff have begun overtime shifts to provide extra water for newly planted trees.
How you can help: This video demonstrates the best ways to water street trees.
Understanding lake algae
Hot, sunny weather rapidly warms the city’s lakes and promotes rapid growth of algae. MPRB has already received reports of filamentous algae at several lakes.
This type of algae forms greenish mats on the water surface and can be nuisance – but it also provides cover for aquatic insects, snails, and other animals that are valuable fish food.
Filamentous algae is sometimes confused with blue-green algae, which is a type of cyanobacteria. Both float on the surface of lakes and ponds, but there is an easy way to tell them apart: Try using a stick to lift the algae out of the water. Filamentous algae has a stringy consistency and clumps together when lifted.
MPRB begins monitoring water quality at beaches, including potential toxins, when life guard season begins: typically over Memorial Day weekend.
- MPRB resources on filamentous algae include Filamentouse Algae Fact Sheet
- Minnesota Department of Natural Resources (DNR)
Fish die-offs
Fast warming water causes stress for fish and leaves them more susceptible to illness. Certain disease-causing bacteria are always present in fish populations but seem to affect fish more often in spring, when they are already stressed from spawning.
When a fish-die off occurs, it is usually a small percentage of the total population that is affected. Panfish are most often affected, but occasionally northern pike can be susceptible. No fish kills have been observed this season in the Minneapolis lakes.
- More on fish kills and die offs (Minnesota DNR)