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I I I I I I I I I I I I I I I I I I I Future Urban Landscape Water ReQuirements An analysis of the per acre water requirements of bluegrass is shown in Table 2. Bluegrass water requirements are used as a basis for estimating total annual water requirements because bluegrass is the most water consuming planting in the landscape. Tree and shrub plantings, and other turf grass varieties, generally have a lower water requirement. So, using a presumption of bluegrass for all landscape plantings, is not only conservative but make the analysis simpler. Although bluegrass is the most water consuming planting in the landscape, it is also quite drought tolerant as is shown by recent research conducted by Dr. Tony Koski with the Horticulture Department at Colorado State University. Dr. Koski has noted: "We know, pretty confidently, that bluegrass can tolerate season-long drought here in Colorado (that is, no irrigation for an entire summer). My thinking is that it is better to let the turf remain dormant coming out of spring, rather than greening it up with some irrigation and then letting it become dormant AGAIN by withholding water. Of course, when the bluegrass is finally irrigated again (and/or we get some late summer monsoon precipitation) it will take awhile for it to get back to good/great turf condition. And there will be some turf loss, but HOPEFULLY not enough to be a problem. Overseeding is always an option if the turf is too thin. I have bluegrass here on campus that has not been irrigated at all for at least 14 years. It doesn't look the best after all of that time - but it is still hanging in." Table 3 utilizes the landscape water requirements from Table 2 and projects the total water requirement for the landscape plantings noted by month for a normal (average) year. Landscape treatments, and the areas of each, are estimated based on other land developments in the region. Water availability is also presented in Table 3 with the early season versus late season requirements separated. So, July has two columns in case some of July falls in the early season and some in the late season. Under Lake Canal, the normal situation is that the direct flow right would be available until July 1SI, so it is assumed that no early season water is available in July. Note that the early season water requirement of 2,311 AF compares favorably with the availability of 7,800 AF from Lake Canal's direct flow right and a surplus of more than 5,000 AF is projected during a normal year? The late season water requirement of 2,998 AF can be compared to the water availability of 2,390 AF from reservoirs plus approximately 2,560 AF from augmented wells for a total of 4,950 AF. It should be noted that having late season water availability greater than water requirements is possible because of an assumption that the open space areas planted in native grasses would not be fully irrigated in the late season, even in a normal year, considering the limited supply of late s~ason water. It would also be possible to completely withhold irrigation from open space areas. This, in fact, would be the first level of drought response. A philosophy or sorts is inherent in this approach and does present enormous flexibility for the minor or moderate drought condition. The direct flow, 3 This water surplus could be taken to water court in consideration of the change potential or it could be available for exchanges with other entities. Aqua Engineering, Inc. June 7, 2004 Canal Modernization Feasibility Study - 6 -