Walter was born in Montana and moved to Idaho falls in 1915.

"Walter, a gentleman in every detail, was my boyhood and life long friend. Had he sat at King Arthur's round table he would have been the greatest and noblest of all the Knights. Our last fishing trip was about 1962 when Walt, his brother Harry, and myself climbed into my camper and went to Island Park on opening day. We had our limits of fish long before we were through fishing and spent considerable time in the afternoon just reminising and enjoying a leisurely trip home.
Sadness and melancholy crept into Walt's life when he lost his wife Althea after a few years of marriage. He later remarried. Walt was childless and loved little children so much. He would have been a wonderful father."
(taken from life history of Joseph William Tolley friend of Walt's)

1910 US Census Montana
Name: Walter E Mooney
Residence: Billings Ward 2, Yellowstone, Montana
Marital Status: Single
Race : White
Gender: Male
Father's Birthplace: Montana
Mother's Birthplace: Minnesota
Family Number: 36
Page Number: 2
Household Gender Age Birthplace
SELF Chas E Mooney M 31y Montana
WIFE Nellie A Mooney F 29y Minnesota
SON Walter E Mooney M 9y Montana
SON Frank L Mooney M 8y Montana
SON Harry L Mooney M 4y Montana

States Census, 1920 Idaho
Name: Walter Mooney
Residence: , Bonneville, Idaho
Estimated Birth Year: 1902
Age: 18
Birthplace: Montana
Relationship to Head of Household: Son
Gender: Male
Race: White
Marital Status: Single
Father's Birthplace: Montana
Mother's Birthplace: Minnesota
Household Gender Age Birthplace
SELF Charles E Mooney M 42y Montana
WIFE Nellie E Mooney F 39y Minnesota
SON Walter Mooney M 18y Montana
SON Frank L Mooney M 17y Montana
SON Harry L Mooney M 13y Montana
SON Albert S Mooney M 2y6m Idaho

1930 US census California
Name: Walter E Mooney
Event Date: 1930
Event Place: San Francisco (Districts 1-250), San Francisco, California
Gender: Male
Age: 30
Marital Status: Married
Race: White
Birthplace: Montana
Estimated Birth Year: 1900
Relationship to Head of Household: Head
Father's Birthplace: Montana
Mother's Birthplace: Minnesota
Household Gender Age Birthplace
Head Walter E Mooney M 30 Montana
Wife Aletna Mooney F 45 Iowa

United States Census, 1940 California
Name: Walter Mooney
Event Year: 1940
Event Place: Assembly District 25, San Francisco, San Francisco City, San Francisco, California, United States
Gender: Male
Age: 39
Marital Status: Widowed
Race White
Relationship to Head of Household Head
Birthplace: Montana
Estimated Birth Year: 1901
Residence in 1935: Same Place