3.1 Winter Month Demand and Supply
Regarding the City’s future use of water Mr. Hickmann says the following:
…for six to seven months of the year the City will be able to meet 100 percent of its demand from the surface water supply in twenty years {A-14}
Comment: The City estimates that water use demand will approach 13.6 mgd (or 21 cubic feet per second or cfs) by 2030 (Table 30 of HDR Hydropower Report of 8/5/2011). Winter month demand in recent years has varied between 5 and 6 mgd. The new pipe capacity with the SWIP will be 13.6 mgd. Mr. Hickmann’s comments reflect a belief that demand will almost triple in the next 20 years. This assumption is convenient as it means that the hydropower revenues also grow rapidly.
Outside the irrigation season, which runs from April 1 to October 31st, there is a five-month period during which the City competes for stream flow in the creek only with the instream water right that is held by the State and was filed by Oregon Department of Fish and Wildlife. For the five non-irrigation months (not the six to seven months quoted) the City has the rights and water is available so that the City could meet 100% of its projected demand for 2030 of 21 cfs from Tumalo Creek. However, at present the City does not currently meet its winter need, which averages around 6 mgd, from its surface water system. Storms in the watershed create turbid flows that the City does not want in their system. As a result, when these events occur, the City does not take any surface water into its system at Outback. Over the last five years the City has, on average, had to avoid taking surface water 62 days a year. The majority of these days are during the winter or early spring months. The City has suggested that the membrane treatment facility will eliminate these shutdowns. This would not be the case if the City went with the less expensive UV (ultraviolet) treatment system.
Thus, it might be more appropriate to suggest that the City may be able to meet a large proportion of its future winter demands for 5 to 6 months. The turbidity of the creek and the junior nature of the City’s irrigation season water rights suggest Mr. Hickmann may wish to limit his enthusiasm in this matter.
3.2 Summer Months Supply and Demand
Regarding its use of surface water, particularly during the summer, Mr. Hickmann states:
“The City uses surface water as its primary source …. Surface water is supplemented with groundwater to meet peak summer demands {A-1, B-6}
Distribution of water rights by seniority occurs when flows are low to help protect the creek. When the City is placed under distribution, this is typically for less than two months of the year when this does occur. This is not a frequent and long term event which would make the surface water supply less reliable. {A-15}
Comment. Mr. Hickmann provides no evidence to support his assertion that “typically” this distribution occurs “less than two months” a year. In fact, an analysis of the City’s past use of surface water during the Irrigation Season indicates that the City’s water rights on Tumalo Creek are regulated at least a portion of each month for the period April through October (seven months). It is estimated that the City’s water rights on Tumalo Creek are regulated an average of 79% of the time during Irrigation Season, including over 90% of the time on average in the months of June through October. This finding suggests, that in planning for SWIP, the City has over-estimated its water right availability. This unduly pushes more costs on to the groundwater only alternative and overstates the revenues from hydropower when comparing SWIP to alternatives.
Note: The full analysis referenced will be included in the unabridged version of this document.
Next up: City Water Use and Tumalo Creek
