Laserfiche WebLink
<br />!' - <br /> <br />. <br /> <br />. <br /> <br />. <br /> <br />STATE OF COLORADO <br /> <br />Colorado Water Conservation Board <br /> <br />Department of Natural Resources <br />1313 Sherman Street, Room 721 <br />Denver, Colorado 80203 <br />Phone' (303) 866-3441 <br />FAX, (303) 866-4474 <br /> <br />Q <br /> <br />Bill Owens <br />Governor <br /> <br />MEMORANDUM <br /> <br />Greg E. Walcher <br />Execuhve Director <br /> <br />TO: <br /> <br />Peter H. Evans <br />CWCS Director <br /> <br />Colorado Water Conservation Board Members <br /> <br />FROM: <br /> <br />Dan McA uliffe <br />Depu ty Director <br /> <br />Tom Browning <br /> <br />DATE: <br /> <br />May 15,2000 <br /> <br />SUBJECT: Consent Agenda Items 4-4.a and 4-4.b, May 22-23, 2000, Board Meeting - <br />Approximate Hydrology Guidelines <br /> <br />EXECUTIVE SUMMARY <br />Consent Agenda Items 4-4.a and 4-4.b include 2 regional regression equations that can be used to <br />estimate approximate lOa-year peak flow values for unstudied or approximate floodplains in the <br />Dolores River basin and in the eastern portion of the San Juan River Basin in Colorado. The 2 <br />equations are part of the CWCB's "Guidelines for Determining lOa-year Flood Flows for <br />Approximate Floodplains in Colorado" (Guidelines). The Board, during previous meetings, <br />approved regional regression equations in the Guidelines for the South Platte River Basin and <br />Arkansas River Basin. <br /> <br />DISCUSSION <br />CWCB staff has developed regional regression equations to estimate lOa-year peak flow values for <br />unstudied or approximate floodplains in Colorado. The regional equations were developed using <br />statistical analyses on existing (published) hydrology information that has been previously <br />designated and approved by the Board. The regional equations use the drainage area of the basin as <br />the independent variable, and peak flow as the dependent variable. This technique allows CWCB <br />staff and others to compute lOa-year peak flow values for the purpose of meeting the CWCB's <br />"Rules and Regulations..." for the designation and approval of approximate floodplain studies. <br /> <br />Dolores River Subregion: <br />This subregion includes the Dolores River mainstem and its tributaries in southwestern Colorado. <br />Streams in this subregion are located in portions of Dolores County, San Miguel County, Montrose <br />County, and Mesa County. Major tributaries in this subregion include the San Miguel River, <br />Naturita Creek, and West Dolores River. The subregion is bounded as follows: <br />