Laserfiche WebLink
<br />large increase in ground water flow and ground water levels during June 2003 led to the large <br />water table rise and sharp increase in stream flow. <br />Chemically the stream appears nearly identical to water discharging from the north and <br />south side ofthe spring area, and in late June considerable surface water flowed into the study <br />site from the east. The Spring Creek wetland and creek appear to be controlled completely by <br />ground water flow from the hill slopes east of the study site. <br />Maintaining ground water flows sufficient to saturate the sedge zone of the spring slopes <br />is critical to the persistence of these plant communities. These high ground water levels <br />occurred only when Spring Creek flows were near its peak of 10 cfs. Thus, maintaining ground <br />flows sufficient to produce stream flows of approximately 10 cfs is critical for maintaining the <br />wetland communities at the spring. <br />Since ground water is recharged by snowmelt, and the movement of this ground water <br />pulse takes 1-3 months to flow through the study site, maintaining an intact watershed with <br />natural ground water recharge and flow processes is essential for the continued functioning of <br />the spring. In addition, ground water levels have to rise several feet in the early summer to <br />create the saturated and anaerobic conditions that will maintain the native plant communities of <br />the springs, and prevent the further invasion of exotic plants. Flows of 0.5 to 2 cfs are base <br />flows, as demonstrated by this study. Flows of2-5 cfs are common on the ascending or <br />descending limb of the summer hydro graph. But much larger flows, likely of 7 -15 cfs occur on <br />most years, and support the stream channel characteristics, and wetland vegetation. <br />Suggested Hydrologic Criteria for Protecting Spring Creek Wetland: <br />1. Stream flow is a function of ground water flow at this site, and not the reverse. To <br />protect the wetlands ground water flow must be protected. Thus, ground water <br />extraction in the watershed above the spring complex could negatively effect ground <br />water flow to the wetlands and thus to the Spring Creek. <br />2. Because Spring Creek is supported by ground water flows from the region of the <br />study site, the flow of Spring Creek that would protect the spring ecosystem complex <br />is the ground water/stream flow that creates seasonally high water tables throughout <br />the spring complex. These water levels, which occurred in late June and early July of <br />2003, were greater than 10 cfs. <br /> <br />14 <br /> <br />. <br /> <br />. <br />