|
<br />..;. ,
<br />
<br />Instream Flow Recommendation(s)
<br />
<br />1 BLM's instream flow recommendation is for 1.80 cfs (May 1 - October 31) & 1.35 cfs
<br />(November 1 - April 30) (see BLM letter in Appendix A),
<br />
<br />-
<br />
<br />Land Status Review
<br />
<br /> Total Length Land Owners hiD
<br />Upper Terminus Lower Terminus (miles) % Private % Public
<br />headwaters Fourmile Creek 7,5 40 60
<br />
<br />This segment is approximately 60% public land and 40 % private land, 50% of the public land is
<br />managed by the BLM and 50% by the U,S, Forest Service (See Figure I),
<br />
<br />Biological Data
<br />
<br />The BLM has conducted field surveys of the fishery resources on this stream and have found a
<br />natural environment that can be preserved, As reported for this reach of stream in their
<br />September 25, 1998, letter to the CWCB, "The stream environment has experienced historical
<br />dredge mining activity but has made a remarkable recovery, Riparian vegetation has been fully
<br />established along the creek, stabilizing both the banks and the stream channel. Substrate, water
<br />quality and food supplies are good for salmonids, However, a paucity of pool habitat and lack of
<br />cover in some reaches are limiting factors, In addition, the Pikes Peak Granite, which erodes
<br />easily throughout this region, and from the nearby highway, has a tendency to fill pool habitat.
<br />Therefore, maintaining adequate flows is important for scouring pools, and for preventing late
<br />summer fish kills because of high stream temperatures, Fish surveys indicate that the reach
<br />supports a self-sustaining population of brook trout." (see BLM Fishery Survey in Appendix B),
<br />
<br />e Field Survey Data
<br />
<br />BLM and CWCB staff used the R2CROSS methodology to quantify the amount of water
<br />required to preserve the natural environment to a reasonable degree, The R2CROSS method
<br />requires that stream discharge and channel profile data be collected in a riffle stream habitat type,
<br />Riffles are most easily visualized, as the stream habitat type that would dry up first should the
<br />streamflow cease, This type of hydraulic data collection consists of setting up a transect,
<br />surveying the stream channel geometry and measuring the stream discharge, Appendix B
<br />contains copies of the field data collected in regards to this proposed segment.
<br />
<br />Biological Flow Recommendations
<br />
<br />The CWCB staff relied upon the biological expertise of the cooperating agencies to interpret the
<br />output from the R2CROSS data collected to develop the initial, biologic instream flow
<br />recommendation, This initial recommendation is designed to address the unique biologic
<br />requirements of each stream without regard to water availability, Three instream flow hydraulic
<br />parameters, average depth, percent wetted perimeter and average velocity are used to develop
<br />biologic instream flow recommendations, The CDOW has determined that by maintaining these
<br />three hydraulic parameters at adequate levels across riffle habitat-types, aquatic habitat in pools
<br />and runs will also be maintained for most life stages of fish and aquatic invertebrates (Nehring
<br />1979; Espegren 1996),
<br />
<br />e
<br />
<br />For this segment of stream, two data sets were collected with the results shown in Table 1 below,
<br />The two surveys are listed in the order of where they are located on the segment, starting from
<br />the most upstream survey to the most downstream survey, Table 1 shows who collected the data
<br />(Party), the date the data was collected (Date), the measured discharge at the time of the survey
<br />(Q), the accuracy range of predicted flows based on Manning's Equation (240% and 40% of Q),
<br />
|