Laserfiche WebLink
Results of Stream Realignment and Low Water Crossing Installation <br />As a result of the fairly low precipitation rates during the summer there were no additional <br />heavy flows that came down Coal Creek from the south. The sand veneer laid down in the upper <br />portion of the realignment had an opportunity to become at least somewhat vegetated. However, the <br />vegetation is more of an upland character rather than a streambed character. This may not be a <br />permanent condition however as most of the plants that invaded the sand are pioneer species well <br />suited to a sandy medium. Because the sand veneer is not very thick it is suspected that willow and <br />cottonwood will appear next and will become established provided no more sand arrives in the next <br />couple of years. If that can occur then sand encroachment may not be that much of a problem. <br />Elsewhere in this area the vegetation is continuing to develop well, both on the slopes and in <br />the stream bed. Even some of the cottonwoods in or adjacent to the streambed are becoming fairly <br />large. They probably would not survive a very large flood, but minor flooding should not bother <br />them. <br />Following are a couple pages of photos showing a comparison to what it was like when the <br />project began and what it is like today. As can be seen the main channel is holding well, but the old <br />main channel that was filled and revegetated is hardly even recognizable anymore. The trees in this <br />area, all of which are quite old, seem to have slowed a bit in their decline. That is probably more due <br />to better general moisture conditions than existed five or six years ago when the drought effects were <br />reaching a peak impact. Nevertheless this old grove will continue to decline. Now, however, <br />conditions have been created in the new topography to allow replacement to occur and it certainly <br />appears that replacement is occurring, albeit slowly. <br />Although the streambed contains a fair number of cottonwoods, as is true north of the road <br />crossing, it appears that willow is becoming more and more dominant in the actual streambed. This <br />is certainly not unexpected and it is suspected that this step is just one step in the process of the <br />vegetation becoming differentiated with more willow in the streambed and cottonwood along the <br />edges on somewhat higher ground where groundwater is accessible but the soil is well below <br />saturated. It is well known that the willows in the streambed are well adapted to living in saturated <br />soil while cottonwood cannot survive for long in those soils. <br />2010 Annual Report Coal Creek Wetland Mitigation Permit DA 198811488 Page 5