Nob Hill Wellhead Protection Plan

The Nob Hill Water Association was formed in 1908 and was originally supplied water by the Pacific Power and Light Company who at that time was the owner of the water system for the City of Yakima. In the 1940s, the City of Yakima gained ownership of the portion of the system that served the City of Yakima from Pacific Power and Light Company.

In 1946 Nob Hill Water Association became independent of the City of Yakima. Presently Nob Hill Water Association has 6 wells, 5 reservoirs, and over 105 miles of largely asbestos-cement piping.

The 6 wells owned by the Nob Hill Water Association include:
  • Well Number 1, drilled in 1946, operated in emergency status, and pumping 1,400 gallons per minute.
  • Well Number 2, drilled in 1956, operated as a primary source, and pumping 800 gallons per minute.
  • Well Number 3, drilled in 1969, operated as a primary source, and pumping 2,250 gallons per minute.
  • Well Number 4, drilled in 1987, operated in emergency status, and pumping 500 gallons per minute.
  • Well Number 5, drilled in 1986, operated as a primary source, and pumping 2,150 gallons per minute.
  • Well Number 7, drilled in 1983, acquired in 2007, operated as a primary source, and pumping 1,200 gallons per minute.
The Association has total certified water rights in the amount of 8,882 acre-feet. The Association’s sources have historically provided high quality water.

Wellhead Protection Area Delineations
The Association's wellhead protection areas (WHPA) were delineated using an analytical model. The following table summarizes the acreage covered by each WHPA.

Analytical Model Area (Acres)

Source 6-Month
1-Year 5-Year 10-Year
Well No. 1
2.7 5.7 54.1 196.1
Well No. 2
6.0 13.1 185.3 604.4
Well No. 3
25.2 48.7 253.3 591.0
Well No. 4
1.9 3.1 12.8 24.4
Well No. 5
14.7 28.4 36.7 273.6
Well No. 7
23.4 46.2 233.7 465.3

Inventory of Potential Contaminant Sources

After delineating the WHPAs associated with the Association’s wells, an inventory of existing and potential sources of groundwater contamination was compiled and mapped. High risk potential contamination sources located near the Association's wells include hazardous substance handlers, underground storage tanks, and agricultural land which may be susceptible to pesticide use.

Contingency Plan

The Association's contingency plan consists of the following components:
  • Susceptibility Assessments: The Washington State Department of Health (DOH) has ranked all of the Association's primary wells as having a low susceptibility to contamination, except for Well Number 2, which was ranked moderate.
  • Source Deficiencies: The Association can currently meet the system maximum day demand with all sources in service as required by the DOH. However, if the largest well (Well Number 3) becomes contaminated, the City cannot meet its 20-year maximum day demand by approximately 1,000 gallons per minute. The The Association acquired Well Number 7 in 2007 in order to provide additional source redundancy and source capacity.
  • Emergency Response: The Association has developed an emergency response plan that includes an emergency call-up list and response procedures for spills, fires, and water supply contamination.
  • Short-Term and Long-Term Water Supplies: The Association currently has 2 interties with the City of Yakima which could be used in the event of contamination of a well. Additionally, there is the potential for future interties with the City of Union Gap. Interties represent the most appropriate short-term supply for the Nob Hill Water Association in emergency situations. Further use of interties, new source development, and groundwater remediation are the most appropriate long-term alternatives.

Local Management Plan

Local management efforts adopted by the Association include:
  • Posting of street signs at wellhead protection area boundaries
  • An annual school seminar program to promote wellhead protection and water education
  • Distribution of literature
  • Notification of residences and businesses within the Association's wellhead protection areas
View the Regional Management Plan page for more information.