Record Details
page 3-49
Digital Collections at BYU
| Field | Value |
|---|---|
| Title | page 3-49 Diamond Fork System Final Supplement to the Final Environmental Impact Statement, page 3-49 |
| Coverage | Electronic reproduction; |
| Format | 3-49 text/PDF |
| Rights | Brigham Young University; http://lib.byu.edu/about/copyright/generic.php Public Domain Public |
| Language | English; eng; en |
| Relation | Central Utah Project; Western Waters Digital Library; wetland resources riparian vegetation coarser sediments could gradually rebuild under the aggradation aggravation that would occur in this reach leading to the possibility of some pool development riparian vegetation would colonize some stream margins and channel bars under the proposed action but the riparian vegetation in this reach including some cottonwood trees and willows dominated by coyote willow is not expected to change dramatically coyote willow would grow into the streamside margins previously inundated by high summer flows and several other willow species likely would grow in small clumps near established willows of the same species there would be no measurable change in riparian vegetation width along the stream channel because it is entrenched and the change in water surface elevation would be within the root zone of existing riparian vegetation diamond fork creek is a gaining stream in this reach most existing cottonwood trees are perched above the boundary of the floodplain flood plain and likely receive water from upslope up slope areas as well as some recharge from high streamflows stream flows there is limited potential for new cottonwood establishment along the stream margins in this reach 34642.4 346424 346424 diamond fork creek below diamond fork creek outlet SVP irrigation flows in this reach have caused numerous changes in the stream system since 1913 this section includes a qualitative summary of the impacts of removing the irrigation flows and providing minimum strearnflows streamflows stream flows in this reach under the proposed action longterm long term watershed characteristics and vegetative cover would not be changed from baseline conditions streamflow strearnflow Stream flow would decrease in the summer and increase in the winter compared to baseline conditions see table 32 3 2 in chapter 3 section 32642 326421 32642.1 3264.2 326421 32642 1 sediment transport would be greatly decreased from baseline conditions see table 311 3 11 in chapter 3 section 336421 33642.1 33642 3364.2 336421 33642 1 average monthly stream temperatures would decrease from baseline conditions see table 310 3 10 in chapter 3 section 33642 336421 33642.1 3364.2 335421 336421 33642 1 strearnbank streambank Stream bank erosion would not change much from baseline conditions al though streamflows strearnflows stream flows under the proposed action would be lower during the summer compared to baseline flows the streambanks stream banks would continue to erode under flood flows daily freeze and thaw cycles and other erosion mechanisms the channel morphology from diamond fork creek outlet to brimhall canyon would remain fairly stable with minimal repeated lateral migration or excessive bank erosion the channel would continue to have a moderate gradient and remain partially entrenched some narrowing would occur under the lower flows and overflow channels likely would be dammed with sediments and no longer convey flow except during high spring runoff the streamside sediments would gradually rebuild in this reach from natural sources and reduced sediment transport capacity providing some opportunities for colonization by riparian vegetation under the proposed action the reduced flows and sediment transport would substantially alter the channel morphology in diamond fork creek from Brini brinl brimhall hall hail canyon to spanish fork river outlet this reach likely would continue to be unstable and dynamic with major changes in the channel associated with large floods the stream would continue to be oversupplied over supplied with sediment from channel storage tributary sources and eroding alluvial fans and terraces trihey and associates 1997a future major floods would send large amounts of sediment into the primary channel effectively plugging it and causing floodwaters flood waters to seek a new pathway the newly formed channel likely would have a straight course down the valley resulting in a significant change after each flood recedes trihey and associates 1997a riparian vegetation along diamond fork creek from diamond fork creek outlet to brimhall canyon would be largely unaffected by interim operation of the proposed action the existing cottonwood forests would continue to age with little or no woody species regeneration because of the limited floodplain flood plain area under the proposed action flows trihey and associates 1997a coyote willow would be the dominant riparian shrub to colonize the stream margins with other willow species growing in small clumps near existing stands sediments would be deposited 349 3 49 diamond fork system FSFEIS FS FEIS |
| Identifier | http://cdm15999.contentdm.oclc.org/cdm/ref/collection/WesternWatersProject/id/9851 |
