[5][6] In the 1990s, the entire 15,000-acre area south of Little Table Mountain and east of Highways 41 and 45, including Sumner Hill, started being called "Rio Mesa".

[7] In a subsequent lawsuit, the Rio Mesa developers won a $25 million judgment against a national title insurance company for failing to defend their access to the river through Sumner Hill.

[10] In 1983, the County of Madera approved the creation of Sumner Hill as a residential subdivision, on the condition that a security gate and perimeter fence were installed.

[2] Early Sumner Hill residents included members of the Peck family, who were fourth-generation farmers in San Joaquin Valley.

[2] The two-lane road leading to Sumner Hill passes vineyards and pastures,[5] and citrus orchards are also visible in the surrounding area.

[8] Sumner Hill residents filed a lawsuit in 2006, after the developers tried to prevent them from accessing the San Joaquin river bottom by installing gates and hiring security guards, and invited the general public to enter their subdivision.

"[9] The case Sumner Hill Homeowners' Association, Inc. v. Rio Mesa Holdings, LLC has also been cited for affirming that "an interest as small (or large) as a simple right-of-way easement can serve as a basis for a slander of title suit.