Below are some links that will be very helpful in your research.
General County info https://www.maine.gov/sos/kids/government/counties
Maine County Commissioners Association (With links to each specific county) https://www.mainecounties.org/maine-counties.html
Lakes / Ponds https://www.maine.gov/ifw/fishing-boating/fishing/fishing-resources/lake-survey-maps/index.html
Historical Societies https://www.maine.gov/sos/arc/organizations/histsoc.html
Maine Encyclopedia https://maineanencyclopedia.com/category/government/counties-government/
Highest points http://www.peakbagger.com/list.aspx?lid=13313&u=ft&hu=0&w=0&pt=prom
Cities and Towns https://maine.hometownlocator.com/counties/
Famous Mainers https://bangordailynews.com/2012/01/06/living/the-famous-faces-of-maine/ https://www.biography.com/search?query=maine Interesting county specifics https://raogk.org/counties/maine/#county
Maine.gov https://www.maine.gov/portal/index.html
HISTORY This is historical info written in the 1800s. Some of it requires some careful reading. Struggle with it for a while. It will help with describing the landscape of your county as well as with history and boarders. http://history.rays-place.com/me/
Tourist attractions. Choose a major city in your county and see what’s nearby. https://www.tripadvisor.com/Attractions
Interactive map with lots of information you may find useful. https://visitmaine.com/interactive-map
Name origins and much more info found here. https://www.ereferencedesk.com/resources/counties/maine/
UPSIDES AND DOWNSIDES INSPIRATION! Find local news publications here. http://www.abyznewslinks.com/uniteme.htm
USDA Data Search Tool https://www.nass.usda.gov/Quick_Stats/CDQT/chapter/1/table/9/state/ME/year/2017
US Census data search tool https://www.census.gov/quickfacts/fact/table/ME/IPE120218
Maine Colleges and Universities https://www.maine.gov/portal/education/colleges.html
Occupation, Education, Income https://www.maine.gov/labor/cwri/county-economic-profiles/countyProfiles.html