Betty M. Foster collection on Save Eagle/Castle Rock

Betty M. Foster relocated to Boise, Idaho, in 1957; she and her family moved into a house on Hillview Drive in the East End Neighborhood. In 1990, she became aware of Morningside Heights, a proposed 177-unit subdivision along Castle Rock Ridge, north of her neighborhood. The Boise City Planning and Zoning Commission granted a conditional use permit on March 27, beginning a years-long conflict between the developers and concerned citizens.

Betty, along with members of the East End Neighborhood Association (EENA), opposed the development due to worries about school overcrowding, traffic, geologic problems on the hillside, and the area’s importance to native tribes. The Shoshone-Bannock and Shoshone-Paiute tribes opposed development on the ridge near a rock outcropping—known to the tribes as Eagle Rock after Chief Eagle Eye—because of the area's importance as an ancestral burial ground and place of spiritual significance.

After several years of negotiations, the developer, Boise City, the EENA, and the tribes settled in 1993. The settlement allowed 34 acres of the ridge to be developed while preserving a 50-acre tract for open space. The City paid a $500,000 down payment for the 50 acres, with the EENA responsible for raising the remaining $75,000.

Betty created the Save Castle Rock fundraising committee to collect donations by the January 1996 deadline to secure the purchase. After the land purchase, the committee continued collecting donations, which were eventually used for trail signage. In 2009, Betty raised money to purchase a tribute stone at Chief Eagle Eye Reserve, formerly Quarry View Park.