DISCUSSION 



Flow reqime, physical characterist 

 stream norpholoqy of Beaver Creek, it's 

 tributaries to the lower Yellowstone Ri 

 to other southeastern Montana prairie s 

 is usually characterized by two hiqh-wa 

 larqest, occurs durinq late winter or ea 

 snowmelt runoff, while the second occur 

 with the sprinq rains. Flows for the s 

 represent an extremely low flow, while 

 averaqe. 



ics, chemical parameters and 

 tributaries and the small 

 ver were found to be similar 

 treams. Runoff in Beaver Creek 

 ter periods. The first, and 

 rly sprinq and represents lowland 

 s in later sprinq and coincides 

 treams in the study area in 1977 

 1978 is considered above 



Diptera is the most abundant and widely distributed qroup of aquatic 

 invertebrates in the Beaver Creek drainaqe. The invertebrate fauna 

 found in Beaver Creek and the tributaries are characteristic of intermittent 

 prairie streams. Distribution patterns in these streams are influenced by 

 the sluqqish water and their intermittent nature. Species which complete 

 their life history in one season appeared to dominate the invertebrate 

 fauna. 



Fishes found in the Beaver Creek drainaqe are similar to those found 

 in other eastern Montana streams (Elser et al . 1978, Elser and Schrieber 

 1978, Clancey 1977). Some exceptions particularly creek chub, Iowa 

 darter, brook stickleback and plains killifish were noted and their 

 distribution identified. In qeneral most species were distributed in 

 Beaver Creek in one of three ways: i.e. found only near the mouth, present 

 only in the headwaters, or distributed throuqhout (Fiqures 13 and 14). Those 

 species found only near the mouth were likely miqrants from the Little Missouri 

 River. Water temperatures, water quality and substrate in the upper reaches 

 favored those fishes found in this area. Other species existinq throuqhout 

 the creek are obviously tolerant of the entire ranqe of conditions and 

 habitats existinq there. 



Comparisons of fish numbers between stations were difficult to make 

 because samplinq conditions between stations varied qreatly. However, 

 for a qiven station, the numbers of each species sampled probably indicate 

 their relative densities. In addition, the abundance or scarcity of 

 certain species at a qiven station probably reflects the suitability of 

 habitat for those species involved. There seemed to be little uniformity 

 in species diversity of the ichthyofauna within the study area. Diversity 

 was qreater above the Montana-North Dakota boundary than below. Samples 

 were not taken frequently enouqh nor were they of adequate size to allow 

 a completely quantitative assessment. 



Observations suqqest that sauqer, walleye and channel catfish 

 utilize Beaver Creek for spawninq. The importance of this stream to 

 maintaininq the fish populations of Lake Sakakawea and the Little 

 Missouri River is unanswered. The lack of anqler returns of taqqed fish 

 indicates an under-utilized resource. This is not unexpected since 

 fishinq pressure is low reflectinq the sparse human population density of 

 the area. 



■75- 



