BOARD00164 ‎(2)‎

• Board Meeting Date: 5/22/2007
• Description: OWCDP Section - Presentation by the Center for Resource Conservation - Impacts and Findings of the Slow the Flow Colorado Irrigation Inspection Program
• Board Meetings - Doc Type: Memo

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Results
Due to the different behaviors of the pre-inspection groups (households watering above
or below ET) it was very difficult to quantify the differences between the means for the
population as a whole. It was more informative to look at the pre-inspection groups
separately.

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When comparing the watering habits of properties that were watering above ET prior to
the inspection with their watering habits after the inspection, a statistically significant
reduction in water usage was observed. Results showed that in 200475% of participants
that watered at rates above ET prior to the inspection reduced their water usage after the
inspection. In 2005, 79% of participants that watered at rates above ET prior to the
inspection reduced their water usage after the inspection.

When comparing the watering habits of properties that were watering below ET prior to
the inspection with their watering habits after the inspection, the trend was to use more
water. However, these properties still watered either at or below the ET rates.

A non-statistical analysis of total outdoor gallons used by the various study groups in
relation to gallons needed to replace ET showed that:

The 2004 group as a whole fell short of meeting the ET rate by 2.6 million gallons in the
pre-inspection year (2003). In 2005, this group fell short of replacing ET by a little more
than 2.6 million gallons (a difference of approximately 56,000 gallons, or 2%.) It was
observed that 2/3 ofthe 2004 group were watering below ET prior to the inspection.

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The 2005 group as a whole watered beyond ET requirements by 5.8 million gallons in the
pre-inspection year (2004). In 2006, this group still irrigated beyond ET requirements,
but by 2.3 million gallons less. This is a 39% reduction in water use, and approximately 7
acre feet of water saved. It was observed that 2/~ of the 2005 group were watering above
ET prior to the inspection.

The cost of conducting the number of inspections in the 2005 group (751) was
approximately $57,000. Current estimates for the cost of infrastructure associated with
the development of water range from $12,000 to $17,000 per ac.ft. at a minimum. This
would indicate that this conservation program is a cost effective method to meeting water
supply needs.

Additional Considerations
The findings of this analysis can play an important role in helping water providers decide
which properties to target for irrigation inspection programs such as Slow the Flow
Colorado, as well as which alternative or additional water conservation measures,
incentives or programs could be considered.

Based on the results ofthis analysis, the reduction of water use attributed to programs
such as Slow the Flow Colorado will depend greatly on whether or not participants are
over-watering prior to receiving an inspection. However, without comparing water

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