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<br />" <br />i <br /> -5- <br /> . South Platte River 100% <br />. . Laramie and North Platte Rivers 90% <br /> . Yampa and White Rivers 81% <br /> . Arkansas River 128% <br /> . Upper Rio Grande 176% <br /> . San MigueVDolores/Animas/San Juan Rivers 155% <br /> <br />It is important to remember the absolute numbers (inches of SWE) in addition to the relative numbers discussed <br />above. A high percentage that represents only a small absolute number of inches of SWE may not represent a large <br />risk, although for certain stream systems that snowpack may be a problem. To provide a little more information, <br />the table below relates the percentages of average listed above to inches of SWE, as of May 12,2005. <br /> <br />SWE % Risk Ranl!e . (1-10'" 10 - 20" '.20-30" . 30.:40" >.40". <br />120% - 140% - 7 3 - 1 <br />140% - 160% 2 4 - 2 2 <br />> 160% 3 10 2 3 1 <br /> <br />NOTE: The total number of SNOTELs with readings above 120% of average listed <br />in the table above (40SNOTELs) is less than the number of SNOTELs listed in the <br />earlier tables (46 SNOTELs); 6 SNOTELs are used to measure snowpack in two <br />basins at the same time, so they were deleted from the table immediately above. <br /> <br />The table immediately above demonstrates that there are a large number of SNOTELS with very high absolute <br />readings, including two stations with readings over 50". It should also be noted that some stations have continued <br />to experience new snow as recently as this week, so it is clearly possible for snowpack to increase in certain <br />locations, even this late. <br /> <br />. <br /> <br />Staff is also working on linking snowpack information to streamflow information. A GIS project is currently <br />underway to delineate subbasins within the major river basins. The maps of subbasins will include SNOTELs , <br />major streams, stream gages, county and municipality boundaries, all shown on the same maps. The most time- <br />consuming part of that project so far has been the delineation of sub-basins, but the expectation is that in late May <br />and early June the project will have progressed sufficiently to allow users to see quickly where the highest <br />snowpack is, where the stream systems and communities are downstream of that snowpack, and where the stream <br />gages are located that would allow measurement of that melted snow once it becomes runoff. A pilot <br />demonstration of that capability will be included in the staff presentation at the May 2005 Board meeting. <br /> <br />Staff will continue to monitor snowpack and streamflows on a regular basis through the rest of May and into June, <br />as appropriate. Updated and revised data can be provided to the Board at the time of the presentation. <br /> <br />F. Enhanced Snowpack Assessment (SNODAS) <br /> <br />The CWCB and the USBR are collaborating on the "Enhanced Snowpack Assessment" Project that uses modeled <br />snowpack from the Snow Data Assimilation System (SNODAS) and tailors and downscales model output to lKrn <br />resolution for Colorado's eight major river basins. The project uses the USGS eight digit Hue basins creating <br />about 44 sub-basins worth of data this aggregated back to the eight major river basins. The two major goals are to <br />1) develop quantitative snowpack numbers, and 2) link modeled snowpack to hydrologic models for streamflow <br />forecasts. Daily maps and two week animated maps for are online at: <br /> <br />. htto://www.usbr.l!ov/omts/rivers/awards/SNODAS/SNODAS CO hist.html. <br /> <br />Flood Protection. Water Project Planning and Finance. Stream and Lake Protection <br />Water Supply Protection. ConservaCion nanning <br />