in the creek decreases just below its confluence due to several imgation withdrawals in 

 the area of the over-wintering facility. In addition, Dutchman Creek is diverted above its 

 natural confluence into a reservoir, which empties into Lost Creek and another irrigation 

 ditch. From visual estimates, the discharge in this ditch (running to the north of Station 

 7) often greatly exceeded the discharge in Lost Creek particularly in July and August 

 when irrigation demand was high. These withdrawals are responsible for the downstream 

 trend of decreasing discharge seen in Fig 1. The increase in discharge at Station 8 is 

 likely due to groundwater and surface return flow from water that has pooled in extensive 

 wetlands below the Dutchman dike and resurfaced as flow in the natural channel of 

 Dutchman Creek and numerous seeps feeding Lost Creek. Overall, Lost Creek did not 

 exhibit the typical downstream increase in flow during runoff in reaches below Station 2 

 where intensive irrigation (which includes storage behind Dutchman dike) moderated the 

 effect of high spring flow. 



Temperature also exhibited a downstream trend as mean summer values increase 

 downstream (see Fig. 2). Note that this apparent increase is likely the result of diurnal 

 variation in temperature, since downstream stations were sampled at times as much as 6 

 hours later in the day than upper stations. No historic temperature data exists for 

 comparison. Flow alteration may also be responsible for the downstream increase in 

 temperature since decreasing discharge volume reduces the heat absorbing capacity of 

 the creek. In addition, the stream reach between stations 8 and 9 has a marked lack of 

 shade-providing woody vegetation, and station 9 exhibits the largest temperature increase 

 between sites from a mean summer value of 14.0 C at station 8 to 17. 1 C at station 9 

 (Note: these sites were sampled within one hour of each other). In the future, diurnal 

 temperature should be assessed in Lost creek with continuous data loggers. 



Turbidity, TSS, and pH are summarized in Table 2 . Turbidity measurements 

 were low, with the exception of one sample date on which turbidity samples were 

 inadvertently frozen, creating a floe. TSS was also low for most sites (<20 mg/1) with 

 highest values measured at Stations 2 and 9. Irrigation diversions appear to have had a 

 positive effect on TSS, providing an opportunity for suspended material and sediment to 

 settle behind diversions like those located above Stations 4 and 7. These diversions, 

 which have depressed peak spring flows may have kept TSS at a minimum. Conversely, 

 Station 2 is not located downstream from any major diversions and exhibited the highest 

 values for TSS with a mean of 49 mg/1 and a peak of 1 73 mg/1. Station 2 is also located 

 along a higher gradient reach than are lower stations, since Lost Creek shifts from a B3/4 

 channel type into a C4 type as it enters the area of the Ueland ranch - roughly between 

 Stations 2 and 4 (Rosgen, 1996). As mentioned above, much of Lost Creek's bed load is 

 comprised of sand and fine sediment , mainly as a result of eroding and slumping banks, 

 with the stream bottom in several reaches composed largely of bank materials. 



Nutrients 



Table 3 presents the results of nutrient samples gathered from May to August of 

 1999. Load calculations were not possible for stations 3 and 6 since discharge was 



