Joseph Nyamumbo
Soc 220
Final Report

Potential Water Usage in Walla Walla's Urban Growth Area


I met with my supervisor, Robert Gordon on the first day to map out the internship objectives. We discussed at length about the internship. I told him I wanted an internship that would offer me an insight into city planning and management, which coincidentally was what he had planned. However, I have been working more on the planning aspect than the management aspect.

I was supposed to build, with the help of GIS staff, layers that will eventually be added onto the preexisting City of Walla Walla base map. I was then to create and add data on these layers to show the projected summary of water usage in the various residential zones .i.e. zones R-96, R-72, R-60 in the UGA. I was also required to project the UGA population, based on the current population growth rate of the City of Walla Walla. This population data will also be attached to its corresponding zone on the base map. Robert proposed that I ignore the third objective as he did not want population to drive the water demand. He alternatively suggested that I calculate how much area is undeveloped in the UGA using the GIS program (see table 3). Essentially the idea was to calculate how much water will be consumed per acre in the UGA (see table 3). The mathematics is shown on the accompanying excel file, which I also presented to Robert.

I will now go through each objective and give detailed information on the objectives and the progress I made in each objective.

My first objective was to establish water use profiles for the City’s standard planning zones based on current and established local use (see table 1). I compiled this data with the help of Darin Christen, who is the Water Quality Specialist at the Water Department. This water consumption data shows the amount of water used by residential and commercial entities per month. For my case and from talking to Darin, I assumed a standard consumption entity to be a single family. Multi-families and apartments skew the water usage data a little bit and thus they were ignored. My second objective was to project water use within the current city limits on current city zones. Later on, Robert Gordon decided that the new projections should only apply to vacant or underdeveloped lots in the UGA and not within the City limits.

My third objective and most important, was to predict using computer capabilities (excel) and available data how much water is needed to sufficiently supply the UGA. To fulfill this objective I had to learn how to calculate the areas for the different zones in the UGA using the City’s GIS system (see table 2-total UGA acreage). I calculated the total area to be 1952.77 acres. Learning to calculate the areas took me longer than anticipated. The area was to help me, as I mentioned, to calculate how much water is consumed per acre in the UGA –I came up with 1252 mg/acre, which was the one figure that Robert wanted (see table 3). Underdeveloped land was included in finding the total area that is developable. Underdeveloped land is considered land containing existing development and has additional development potential.

Most of the Urban Growth Area is currently considered primarily residential and therefore my standard analysis as aforementioned was based on residential households. There are already households present in the Urban Growth Area, which did not affect my projections because the new water projections only applied to vacant land. Robert and I made an assumption that 85% of the land in each UGA zone was developable and our data should reflect that assumption. It was easier calculating the total UGA and zone areas. I encountered a problem towards the end of the project however. The GIS system lacks tools to help calculate areas of isolated patches for the different zones (shaded areas in map). Calculating the areas would help calculate how much water will be consumed per acre in the undeveloped areas. The consumption per acre will then be projected for the next 15 years to evaluate if the City will have enough water for distribution. I have attached an excel sheet with formulas that attempt to achieve this objective.

In general the internship was involving. Four hours were barely enough to produce quality work. Gathering various data sets was complicated. At times the information was present; at times the information was unavailable in the City’s data base. It required further manipulations to collect the information I desired. If not computerized manipulations, I had to peruse the City’s old records to compile the data. An example of this is table 3. This data was not readily available. I had to compile it. Since the residential water usage and population data are collected by different departments, it took me longer than anticipated to gather all the necessary information to start projecting water use for the various zones in the Urban Growth Area. Water usage in the UGA undeveloped zones was the primary objective in this project- which was completed towards the end this project. Robert Gordon and Gary Mabley were very helpful in availing the information from the Census Department. Gary helped me understand the current and planned Urban Growth Area residential zones. These zones represent different sections of Walla Walla County. From what I learned, these sections are divided into either residential zones or industrial zones. For my case, I further assumed the water usage was based on residential zones in the UGA.

Another problem encountered in this internship was the availability of supporting staff. The department is busy and the staff thin. Making appointments with staff was often times difficult. Also, most of the staff was relocated to different offices in the middle of the project and often times to a separate far building. Robert, who was managing the entire project, was also leaving the department. Robert’s departure was obviously a big blow to the project. His knowledge, vision and ambition for this project were instrumental in directing the project. I nevertheless learnt to maneuver my way round these obstacles by intercepting staff whenever I saw them. In addition, the various terms/ field language used was unfamiliar but the terms became progressively familiar.


Value to community:

The population of Walla Walla County is growing. This study will help the City evaluate if it has enough water to satisfy the current water demand and the additional demand from people and industries moving into the county. This study may help reduce shocks that may arise from sudden increases in water demand or sudden shocks from a decline in water supply- emergency planning. The projections are intended to increase efficiency within the City planners and equally cater for low rainfall years. I learnt later too that this water projection in the UGA might in a way help control what type of development takes place in the UGA. It is my understanding that the city would rather have residential areas instead of industries in the UGA. Industries consume more water and if allowed to sprout in the UGA, it might drive water charges up as industries demand more water relative to residences. However, there are areas primarily set aside for industrial development.


This internship would be effectively done if performed by an intern with a solid knowledge and understanding of Walla Walla County. An understanding of the field language would increase grasping the information contained in the GIS program itself and the Walla Walla base map. In addition, prior experience with GIS system and Microsoft excel would be advantageous as most the final data will always be attached to the GIS Walla Walla base map. Microsoft excel is important in doing mathematical manipulations for the various data.

Good public and interaction skills may be helpful in order to help interact with the busy staff members.

This internship has no field aspect to it and that makes it a little bit monotonous. There is a lot of computer work to it.



1. The rate of water consumption in the UGA is equivalent to water consumption within the City.
2. The rate of population growth in the UGA will be constant at 1.2179%
3. Only 15% of the area in the UGA per zone is developed. That leaves 85% of the total area in each zone that is developable.
4. Lastly, water availability in Walla Walla will always increase.


Robert Gordon: City Lead
Darin Christen: Water Quality Specialist/ GIS
Gary Mabley: City Planner for the UGA




City Limits
(net acres)

County UGA
(net acres)

Total acres
Dwelling Units per acre
Weighted avg.