Laserfiche WebLink
<br />o <br />C-:"l <br />1'':: <br /> <br />:."'" <br /> <br />~ <br />-.J <br /> <br />Category: <br /> <br />Duration: <br /> <br />Frequency: <br /> <br />Purpose: <br /> <br />3, <br /> <br />Category: <br /> <br />Flow> 5,000 cfs during runoff period. <br /> <br />A minimum of 2] days between March] and July 31. <br /> <br />Flows> 5,000 cfs for 2] days or more need to occur in 50% of the years <br />on average for the period of record 1929-1993, Maximum number of <br />consecutive years without meeting at least a flow of 4,850 cfs (97% of 5.000 <br />cfs) within the 65-year period of record is 4 years, <br /> <br />Flows of 5.000 cfs or greater for 21 days are necessary to clean backwaters <br />and maintain low-velocity habitat in secondary channels in Reach 3, thereby <br />maximizing nursery habitat for the system, The required frequency of these <br />flows is dependent upon perturbating storm events in the previous period, <br />requiring flushing in about 50% of the years on average. Backwaters in the <br />upper portion of the nursery habitat range clean with less flow but Illay be too <br />close to spawning sites for full utilization, Maintenance of Reach 3 is <br />deemed critical at this time because of its location relative to the Colorado <br />pikeminnow spawning area (RM 132) and its backwater habitat abundance. <br /> <br />Flow >2,500 cfs during runoff period, <br /> <br />A minimum of 10 days between March land July 31. <br /> <br />Flows> 2,500 cfs for 10 days or more need to occur in 80% of the years <br />on average for the period of record ]929-]993, Maximum number of <br />consecutive years without meeting at least a flow of 2.425 cfs (97% of 2,500 <br />cfs) within the 65-year period of record is 2 years, <br /> <br />Flows above 2,500 cfs cause cobble movement in higher gradient areas on <br />spawning bars. Flows above 2,500 ds for 10 days provide sufficient <br />movement to produce clean cobble for spawning, These conditions also <br />provide sufficient peak flow to trigger spawning in Colorado pikeminnow, <br />The frequency specified represents a need for frequent spawning conditions <br />but recognizes that it is better to provide water for larger flow events than to <br />force a release of this magnitude each year, The specified frequency <br />represents these tradeoffs, <br /> <br />Timing of the peak flows noted in A throu,gh D above must be similar to <br />historical conditions. and the variability in timing of the peak. flows that <br />occurred historically must also be mimicked, <br /> <br />Mean peak flows in the habitat range (RM 180 and below) must be within 5 <br />days:!: of historical period mean, which was May 31, <br /> <br />Duration: <br /> <br />Frequency: <br /> <br />Purpose: <br /> <br />E. <br /> <br />Category: <br /> <br />Timing: <br /> <br />SJRIP Biology Committee <br />February 1999 <br /> <br />8-7 <br /> <br />Executive Summary <br />Flow Repo~ <br />