"February 2010"

The objectives of this study were to: 1) Compile all aquatic macroinvertebrate survey sites within the Custer National Forest (Ashland Ranger District) as a continuing baseline survey and biological assessment; 2) Complete identification and analysis of macroinvertebrate samples collected in 2005 and 2006 that were not processed, 3) test the temporal stability of small spring macroinvertebrate metrics with multiple revisits to established reference sites; 4) Compile all sites sampled from 2004 to present into a comprehensive table of impaired and non-impaired reaches based on habitat and macroinvertebrate metrics; 4) Evaluate management practices that will benefit the long-term sustainability of community integrity at these sites (i.e., cattle exclusion fences, shorter rotational grazing). The goal of this inventory work is to facilitate the Regional Restoration Strategy by filling in gaps in existing data, locating rare elements on the landscape, and identifying opportunities for restoration and management actions. Riparian habitat assessments and macroinvertebrate surveys were performed at 52 lotic (spring/stream) sites and 26 lentic (prairie pools/stock pond/reservoir) sites within the Ashland District from 2004-2008. Four stream sites (3 spatially identical reaches and 1 site upstream ~50m) were revisited from 2004 to 2008 (Cow Creek upstream of the reservoir has 4 years of monitoring data) to evaluate the temporal stability of macroinvertebrate metrics for determining biological integrity. Macroinvertebrate Communities: Overall, 132 macroinvertebrate taxa were collected from all sites between 2004-2008 but no USFS species of concern (SOC) or species of interest (SOI) were discovered. A unique caddisfly, Philarctus quaeris that produces its case from snail shells was found in the Little Bear Creek pools in 2008; this permanent pool site maintains a high diversity of macroinvertebrates (32 taxa), including 5 snail species and many aquatic beetle taxa. The only stonefly taxa (Amphinemura cf. banksi) reported in the Ashland District was found at 3 of the most intact spring systems. Average macroinvertebrate taxa richness per lotic and lentic sites was 20 and 16, respectively, and the highest taxa richness reported was 53 at the Otter Creek 2004 site and 38 taxa at 2 spring sites. Using MT DEQs macroinvertebrate multimetric index (MMI) and the Spring Reference Indicator (O/E), 4 of the 52 lotic sites were ranked non-impaired (excellent biological integrity), 12 were slightly-impaired, 24 were moderately-impaired and 11 severely degraded. Cow Creek above reservoir, Parrish Spring, Prune (Charcoal) Creek Spring and Stocker Branch contain reference condition lotic spring macroinvertebrate communities. While there is no current standardized method for analyzing lentic macroinvertebrates, Cow Creek Reservoir, Mud Turtle Reservoir, and Poker Jim Pond contain highly diverse lentic macroinvertebrate communities, including 5 dragonfly and 5 damselfly species. Cow Creek Reservoir also remains the hotspot for herpetofauna with 5 species reported. In 2008, we sampled 26 sites for macroinvertebrates: 2 of these were site revisits (Cow Creek, Stocker Branch). Taylor Creek, ODell, Hazel Creek and Poker Jim Reservoirs were sampled for macroinvertebrates during the 2005 field season and were processed for this report with the additional funding. Community Integrity results from the habitat and macroinvertebrate surveys combined to rank the Cow Creek reach upstream of Cow Creek Reservoir the most ecologically intact site and the reference condition Northwestern Great Plains Spring Ecological System for the Ashland area, followed by Parrish Spring (2008), Prune Spring (2005), Stocker Branch Spring (2004), and the Charcoal Creek (Prune Spring) 2004 site. Lentic (stock ponds) sites with high macroinvertebrate diversity include Cow Creek Reservoir, Mud Turtle Reservoir and Poker Jim Reservoirs. We recommend choosing these as integrator and future monitoring sites and should be managed for their high diversity and integrity as Northwestern Great Plains Perennial Spring ecosystems. Additional sites that have high ecological potential to recover if cattle exclusion occurs include lower Charcoal Creek, Cow Creek below the reservoir, Davis Prong of EF Hanging Woman, Little Brian Spring #1, Brian Spring #2, Ash Creek Spring and Black Canyon Reservoir Spring

Includes bibliographical references (p. 20-21)

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