Executive Summary 



Project goals of the Aquatic Survey and 

 Assessment of the Slim Buttes Region include: 1) 

 to sample and assess aquatic community integrity 

 based on macroinvertebrate, fish and habitat 

 sampling, 2) to identify and interpret key 

 community indicators found at the sites, using 

 standardized protocols and biotic thresholds, and 

 compare these against reference condition 

 standards at the watershed-level and local-reach 

 scale. 



Riparian habitat assessments, water quality 

 parameter measurements, and fish and 

 macroinvertebrate surveys were performed at 16 

 lotic (stream) sites and 2 lentic (ponded) sites 

 within the Slim Buttes Region of the Little Missouri, 

 Upper South Fork Grand and Upper Moreau 

 watersheds. Seventeen of these sites had fish, and 

 all had macroinvertebrates. Two other visited sites 

 were dry. Three longitudinal sequence stream sites 

 were sampled in the Little Missouri and South 

 Moreau rivers; while 2 sequential sites were visited 

 in the North Fork Moreau, South Fork Grand and 

 Jones Creek basins. Biological community integrity 

 was calculated at all sites using Fish Integrated 

 Biotic Indices (IBFs) and Observed/Expected 

 Models (O/E), as well as macroinvertebrate multi- 

 metrics (MT MMI). Site summary descriptions 

 based on the overall community integrity and site 

 observations are included. 



Habitat Evaluations. Highest site habitat scores 

 using both the EPA RBP (200 max. score) and 

 BLM (24 max. score) habitat assessment methods 

 were measured in the South Fork Grand River 

 basin. South Fork Grand River sites #1 & 2 had 

 reference site conditions for a Great Plains Prairie 

 Stream with EPA RBP scores of 1 88 and 189, 

 respectively. Most stream sites visited in the Grand 

 River basin had higher than average landscape 

 integrity measured at the local reach scale. Two of 

 the 3 sites in the Little Missouri River basin ranked 

 excellent for a Medium-Large Prairie River. The 

 North Fork Moreau River site #2 had the highest 

 integrity of sites visited in the Moreau River basin. 

 Sites in the South Fork Moreau River scored 

 lowest in habitat integrity. The South Fork Moreau 



Site #3 near Hoover showed moderate 

 improvement in habitat integrity from upstream 

 sites, but the water quality parameters showed 

 impairment. The water quality parameters 

 conductivity and turbidity consistently increased at 

 the downstream reaches of a stream series. 



Fish Communities. Overall, 22 fish species (16 

 native/6 introduced or exotic) from 6,227 individuals 

 were reported from all visited sites. Average fish 

 species richness per site was 8, and the most 

 diverse sites were the 3 reaches of the Little 

 Missouri River, with 14 species (1 1 natives). 

 Fathead minnows were collected at 16 of 1 7 (94%) 

 fish presence sites. The next highest frequency of 

 occurrence (FO) is the introduced green sunfish at 

 1 of 1 7 sites, and the sand shiner and black 

 bullhead at 9 of 1 7 sites. Using Montana's Prairie 

 Fish IBI, 6 of the 17 fish sites were ranked non- 

 impaired (good to excellent biological integrity), 6 

 were slightly impaired (moderate integrity) and 5 

 were moderately impaired (poor biotic integrity). 

 No sites were ranked severely impaired by the Fish 

 IBI. The O/E scores agreed with the IBI scores in 

 most cases, except for the smaller Prairie 

 Intermittent Streams; the O/E ranked Campbell, 

 North Fork Moreau # 1 and Crooked Creek as 

 unimpaired (0/E=83.3), while the IBI ranked them 

 as slightly to moderately impaired (IBI=62, 52 and 

 49, respectively). 



Macroinvertebrate Communities. Overall, 118 

 macroinvertebrate taxa were reported from the 

 Slim Butte 2006 assessment sites. Average 

 macroinvertebrate taxa richness per site was 29 

 and the highest taxa richness reported at 2 sites 

 was 50 taxa. Using the Montana DEQ 

 macroinvertebrate multimetric index (MMI), 9 of 

 the 1 8 sites were ranked non-impaired (good to 

 excellent biological integrity), 6 were slightly 

 impaired and 3 were moderately impaired. South 

 Fork Grand River sites # 1 & #2 had reference 

 condition macroinvertebrate scores for a Great 

 Plains Prairie Stream with DEQ MMI scores of 

 75.7 and 69.8, respectively. Most stream sites that 

 contained riffle areas scored much higher with the 

 MMI than sites with exclusively pool areas. Sites 



IV 



