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I e Memorandum Oxley and Jarrett August 19, 1993 Page three SOMETHING TO CONSIDER (WHAT ABOUT RAINFALL INFORMATION?) On my table you may note what appears to be a contradiction with a thought implied earlier in this memo. It is the listing of rainfall as a key parameter under the "Watershed Conditions" methodology. There are two facts that could imply that rainfall information would not be considered in our efforts and that snowpack information would be the only precipitation information we would consider: 1) The values for rainfall flows are the lowest of the three sets of flow values calculated by the Corps of Engineers. 2) We are looking at an area that is either in the mountains or very close (depending on how you look at it). Despite those facts, I don't agree with the conclusion that we should not consider rainfall information. I would like to have both of you examine the revised version of the NOAA Atlas rainfall map that Mark Sawyer and I prepared to see what it tellS us about microclimates in Clear Creek County. If you weren't aware of it, we obtained precipitation data for the NWS stations in and around the county from the State Climatologist's office at CSU, performed a Log-Pearson ill analysis for each station and determined 24-hour rainfall values. We then revised the isohyetallines on the NOAA Atlas map to assure consistency with the values we had calculated at those stations. Even if we conclude that rainfall is an unimportant consideration in flood hydrology in Oear Creek County, I still believe that our rainfall map tells us something useful about the hydrologic differences in the county's subregions. That is all a long explanation for why I included rainfall as one of the key parameters on the attached list LET'S MOVE ON There is one piece of information which I have not addressed in my table: the sources of data. Can you help with that part of the table and with any revisions, deletions and additions to what I have done so far? Make sure that the final list of "key parameters" that we prepare includes parameters that can actually be mapped by us. Assure that the data sources on our list are really available and that they are valid so we can be certain that our objectives are achievable. Because I feel that this project has been around since the last century (or maybe longer) and still is not done, I propose that you revise my table and send it back to me by September 7, 1993 (the day after Labor Day). Maybe we can do all of the real work before we're deep into the winter of 1993 -1994.