Good Morning Sandy, 

Thank you for contacting the U of M Extension Service. 

Please click on the following link about white grubs: https://extension.umn.edu/yard-and-garden-news/white-grubs-return-snow-recedes

Have you inspected the soil under the turf and are you sure it is grub damage? This information states: 

• Healthy turf can tolerate some level of Japanese beetle feeding (about 10 larvae per square foot). 

Here is another link about grub damage: https://extension.umn.edu/news/white-grubs-threaten-minnesota-lawns-identification-and-treatment-tips

This information states: 

Signs of white grub damage include irregular patches of dead or dying grass that look like drought stress. This damage is evident even after watering or rainfall. Moderate damage shows dead turf with few roots when pulled up.

In viewing your photo, the damage is not "irregular patches of dead grass", it appears to be consistently most of the yard. 

We had a drought the last half of last summer. Was the grass watered? 

Have you had a soil test? Here is a link and forms for soil testing: https://extension.umn.edu/managing-soil-and-nutrients/soil-testing-lawns-and-gardens

I will also mention the newer alternatives to lawn turf grass. Turf grass is a sterile environment for nature. Various chemicals applied to the turf grass makes it additionally toxic to our pollinators. Our insects and pollinators are becoming extinct at an amazing rate.

Please click on the following links:

https://extension.umn.edu/lawns-and-landscapes/planting-and-maintaining-fine-fescue-lawn

https://extension.umn.edu/landscape-design/planting-and-maintaining-bee-lawn

Here is a link about turfgrass seed: https://extension.umn.edu/lawn-care/buying-turfgrass-seed-minnesota-lawns

We do not recommend specific chemicals or companies. You would need to read the labels of any pesticide to see if it is safe to apply near a water body. 

Good Luck!