Long Pond was first developed as a water supply by Frank Jones, a brewer and entrepeneur, who in the late 1880s built Hotel Sorrento, a 100 room hotel with a 50 room annex, by the harbor in Sorrento. He hoped it would become "a playground for the rich and wealthy" and, in order to supply the guests with "pure water", he piped water for six miles through a iron pipe from Long Pond to the hotel. An 1890 hotel brochure includes an analysis of the purity of this water as an advertisement to the guests.
In 1902, Frank Jones died and in 1906 the hotel burned down. The Ewing family of Sorrento subsequently bought the property, including the water supply. To manage the water supply, they created a private company, the Long Pond Water Company. The photo below shows a stock certificate issued by the company.
Water originally simply ran downhill from Long Pond to a reservoir on High Head (next to the Treasure Island road)- - no pumps, no procedures except for chlorination. What is left of the original reservoir is shown below:
At some points along the path to the old reservoir, the elevation is high enough that you can see Mount Desert in the distance above the trees.
In the late 1980s, updates to the Safe Drinking Water Act required water companies to install new treatment and purification systems. Private companies did not qualify for the grant money and low cost federal loans necessary to make these improvements affordable to customers. Therefore, the stockholders of the Long Pond Water Company in 1990 dissolved their company and transferred its assets and management to a "quasi-municipal district" (a public corporation or district created under Maine law to deliver limited public services such as water supply) formed by the towns of Sullivan and Sorrento, the Long Pond Water District.