• Combine maple syrup, salt, water, lemon juice and zest in a stainless steel 3-quart or larger stock pot and stir to combine.
• Add the blueberries and bring to a boil over medium high heat. Cook for 2 minutes, stirring constantly, to prevent burning.
• Reduce heat to low. Leave as is for a chunkier syrup or use a hand-held blender to create a smoother, thicker syrup.(Note: you can use a regular blender or food processor, but you'll need to be very careful transferring the hot syrup from the pot and back.)
• To Freeze: Let syrup cool and then transfer to freezer-safe containers. Label and use within a year.

To Can:

• Prepare boiling water canner, jars and lids while the blueberries are coming to a boil. Keep jars warm by keeping filled with hot water and bring canner to just a gentle simmer.
• Once syrup is ready, ladle hot syrup into one hot jar at a time, leaving a 1/4 inch headspace. Remove air bubbles, wipe rim, and attach lids, screwing band until just fingertip tight. Place jar in simmering water canner. Repeat until all jars are filled.
• Bring water to a boil and process both pint and half pint jars 15 minutes, adjusting for altitude.
• Turn off heat, remove lid and let jars sit in canner 5 minutes. Transfer jars to a towel lined surface and let cool 12-24 hours.
• Check lids to make sure they sealed, label and store in a cool dry place. Use within 18 months.
• Once syrup is opened, store in the refrigerator for 1-2 weeks.