Brownell Springs was the City's sole water supply for more than 50 years, (1926 through 1977). Located on 22 acres of City-owned land on the north face of Lenhart Butte (approximately 6 miles east of Sandy) these springs consistently produce 250 to 350 gallons per minute (360,000 to 500,000 gallons per day). Peak flows tend to occur in August and September - the opposite of what one might expect. We assume that there is a lag between the time that winter precipitation enters the geologic formations under Lenhart Butte and the point at which the water emerges from the Springs.
Most of the land above the site is privately owned timberland. Brownell Springs is considered a groundwater source - therefore no filtration is required. The City performed quarterly testing for Giardia and Cryptosporidium cysts in 1992 and 1993 to demonstrate that the Springs are not influenced by surface runoff. Water from the Springs is disinfected with chlorine and then conveyed by gravity to the City.
Brownell Springs produced over 141 million gallons of water in calendar year 2010 - about 36% of the City’s total supply. These springs produce high quality water. Finished water turbidity is consistently in the range of 0.045 NTU (Nephelometric Turbidity Unit (NTU) a measure of the clarity of water.) Turbidity in excess of 5.0 NTU is just noticeable to the average person. The EPA standard is 0.3 NTU.
The DEQ/DHS Source Water Assessment Report for Brownell Springs can be found here (watch out 17 MB file - requires Adobe Acrobat). A hard copy is available in the government document section of the Sandy Public Library