Put washed blueberries and water into a medium saucepan and mash the berries with a potato masher.
Bring the berries to a boil over medium-high heat and keep mashing until they’re broken down.
After they come to a boil, reduce the heat to medium-low and simmer for around 15 minutes, stirring frequently, until the berries are broken down into a sauce.
Place a fine mesh strainer over a large bowl and pour the berry mixture through the strainer, pressing as much of the liquid out of the berries as possible. Discard solids.
Pour the strained blueberry juice, lemon peel and sugar back into your sauce pan.
Bring the sauce to boil, then reduce the heat and allow it to simmer for around 10 minutes. The mixture will slightly thicken.
After the syrup has slightly thickened, pour the lemon juice into the mixture and heat for 1-2 minutes.
Turn off the heat and remove the lemon peel slices. Once cooled, transfer to a pint sized mason jar or 4 four-ounce jars.