Nebraska Public Power District (NPPD) has monitored fish populations annually (except 1998) since 1993 on the Niobrara River in Nebraska, in the vicinity of Spencer Hydropower Project before and after  flushing  or  sluicing  activities. These activities could alter water quality in the river downstream, which can negatively impact fish populations. Intensive sluicing-monitoring studies coupled with operational adjustments indicated minimal impacts were occurring to fish populations in the vicinity of the hydro. Long-term diversity and abundance of fish species has been a historical concern, so annual fish sampling has continued through the present. Of the 13,063 fishes in 26 species sampled below the hydropower complex, six species composed approximately 96.5 percent of the total sample. The most common species sampled were sand shiner, Notropis ludibundus (38.6%); red shiner, Notropis lutrensis (34.0%); flathead chub, Hybopsis gracilis (12.2%); carpsuckers, Carpiodes spp. (5.6%); bigmouth shiner, Notropis dorsalis (3.9%); and channel catfish, Ictalurus punctatus (2.2%). Over the nine-year period, catch-per-unit-effort trends indicated no significant increases or decreases among years sampled and the respective species collected. Fish CPUE was not significantly affected by short-term annual sluicing

Chrisp, Ed Y.

Gutzmer, Michael P.

King, Justin W.

Overhue, David P.

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Transactions of the Nebraska Academy of Sciences and Affiliated Societies Nebraska Academy of Sciences 2002 FISH SPECIES-RICHNESS TRENDS IN THE NIOBRARA RIVER, NEBRASKA, BELOW THE SPENCER DAM Michael P. Gutzmer Nebraska Public Power District, mgutzmer@newcenturyenvironmental.com Justin W. King Nebraska Public Power District David P. Overhue Nebraska Public Power District Ed Y. Chrisp Nebraska Public Power District Follow this and additional works at: https://digitalcommons.unl.edu/tnas  Part of the Life Sciences Commons Gutzmer, Michael P.; King, Justin W.; Overhue, David P.; and Chrisp, Ed Y., "FISH SPECIES-RICHNESS TRENDS IN THE NIOBRARA RIVER, NEBRASKA, BELOW THE SPENCER DAM" (2002). Transactions of the Nebraska Academy of Sciences and Affiliated Societies. 18. https://digitalcommons.unl.edu/tnas/18 This Article is brought to you for free and open access by the Nebraska Academy of Sciences at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Transactions of the Nebraska Academy of Sciences and Affiliated Societies by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 2002. Transactions of the Nebraska Academy of Sciences 28: 57-63 FISH SPECIES-RICHNESS TRENDS IN THE NIOBRARA RIVER, NEBRASKA, BELOW THE SPENCER DAM Michael P. Gutzmer, Justin W. King, David P. Overhue, and Ed Y. Chrisp Nebraska Public Power District 1414 15th Street Columbus, Nebraska 68601 ABSTRACT Nebraska Public Power District (NPPD) has monitored fish populations annually (except 1998) since 1993 on the Niobrara River in Nebraska, in the vicinity of Spencer Hydro-power Project before and after "flushing" or "sluicing" activi-ties. These activities could alter water quality in the river downstream, which can negatively impact fish populations. Intensive sluicing-monitoring studies coupled with operational adjustments indicated minimal impacts were occurring to fish populations in the vicinity of the hydro. Long-term diversity and abundance of fish species has been a historical concern, so annual fish sampling has continued through the present. Ofthe 13,063 fishes in 26 species sampled below the hydropower complex, six species composed approximately 96.5 percent of the total sample. The most common species sampled were sand shiner, Notropis ludibundus (38.6%); red shiner, Notropis lutrensis (34.0%); flathead chub, Hybopsis gracilis (12.2%); carpsuckers, Carpiodes spp. (5.6%); bigmouth shiner, Notropis dorsalis (3.9%); and channel catfish, Ictalurus punctatus (2.2%). Over the nine-year period, catch-per-unit-effort trends indicated no significant increases or decreases among years sampled and the respective species collected. Fish CPUE was not significantly affected by short-term annual sluicing. t t t Nebraska Public Power District (NPPD) owns and operates the Spencer Hydropower Project ("the hydro") on the Niobrara River, approximately 8 km south of Spencer, Nebraska, on the Holt and Boyd County line (Fig. 1). The river, with headwaters in eastern Wyo-ming, flows approximately 800 km eastward across Nebraska,joins the Missouri River near Niobrara, Ne-braska, and drains a watershed of approximately 28,000 km2. The hydro project structure (Fig. 2) was installed in 1927 and at that time consisted of (1) a 1,200-acre reservoir; (2) a short concrete abutment on the north 57 and south banks ofthe river; (3) a powerhouse contain-ing two generators (2,000 kW and 1,300 kW); (4) a spillway with a combination gate bay consisting of four tainter gate bays, five stop log bays, and a sluice gate; and (5) a 3,700-foot long, 18-foot high earth embank-ment. NPPD conducts sediment-flushing activities (sluicing) to remove accumulated sediment from the reservoir above the hydro in the spring and fall. Sluic-ing was historically conducted several times a year dating back to 1948 (Mares 1991). During sluicing, four tainter gates and a sluice gate are typically opened for about a week to essentially drain the reservoir, while flow continues through the facility. Fish in the Niobrara, however, are adapted to highly turbid, vari-able sediment (sand) conditions. It is estimated that the river transports more than 300 metric tons of sedi-ment per day in this reach ofthe river (Hotchkiss et al. 1993). Between 1975 and 1989, periodic fish-kills were observed below the hydro during sluicing. Fish were particularly vulnerable to sluicing in summer, during low flows and high water temperatures. Previous in-vestigators, such as Hesse and Newcomb (1982), stud-ied fish populations in the vicinity of the hydro and expressed concern about its impacts. In 1980 a man-agement variance was drawn up by NPPD and the Nebraska Department of Environmental Control (NDEC now NDEQ, Nebraska Department of Environmental Quality) and the Nebraska Game and Parks Commis-sion (NGPC), stating that NPPD avoid sluicing be-tween April 15 and September 15 each year, except for emergencies, to minimize impact on the riverine fisher-ies during that time. The variance no longer exists, and changes in Title 117, Nebraska Surface Water Quality Standards, reflect this change. All sluicing has been conducted between September 15 and April 15 since 1993. The only exception was August, 1999. 58 M. P. Gutzmer et al. BOYD CountyLine is the river Bristow ••••••••••••••• P ............... ...•••......•.•••...... ~ HOLT ~ denotes sampling areas 1 0 kilometers Figure 1. Spencer Hydro study area in Boyd and Holt counties, Nebraska. We were interested in evaluating fish populations below the hydro to establish data regarding fishery populations and related long-term impacts, particu-larly in the fall, when conditions can be deleterious to riverine biota. The objectives of this study were to determine species composition below the hydro to dis-cover whether the hydro operation was in any way impacting fish species richness on the Niobrara River and to see if any discern able trends could be noted in the species that were sampled. METHODS Fish sampling Sampling was conducted each fall from 1993 through 2001, except no sampling was done in 1998. All fish were sampled by seining and electrofishing within 1.5 km below the hydro (above and below the Highway 281 bridge) and at locations above and below the Lynch bridge, approximately 6 km south of Highway 12 near Lynch, Nebraska (Fig. 1). Minimal fish surveys were conducted above Spencer Dam but were not included in this evaluation for long-term trends (Gutzmer et al. 1996). The seine used was approximately 8 m wide and 1 m high, and the mesh size was 5 mm; haul lengths were 15 m. Sampling occurred before (presluice) and while the gates were open during sluicing (post-sluice). A Smith-Root Model 15-C backpack shocker was used to shock 30.45-m sections of bank habitat. Two dip-nets were used to collect fish. Sampling was done at selected locations (Fig. 1) below the dam, along bank habitats and in some mid-channel habitats that contained shale outcrops or rocky cobble. Initially, in 1993, approximately 10 seine hauls and 10 electroshock segments were sampled above and below the hydro. After 1994 the effort was reduced to accommodate avail-able staff at the time (sampling effort is shown in Table 2). Habitat for seining and electroshocking was fairly Fish below Spencer Dam in the Niobrara River 59 Highway 281 Parking lot PowerHouse Sluice Gate Tainter Gates HYDRO POND ~--Approximately 0.6 kilometer ------+ NORTH Drain to river L _I Parking Lot • I -. - . - . State Recreation Area I • I • _._------oc N Water Quality _'_8\ Highway 281 Figure 2. Map of Spencer Hydro structures and dam on the Niobrara River. accessible the first few kilometers below the hydro, and the river widens near the bridge at Lynch and had ample sandbar habitat for seining. All fish collected from both sampling gears were enumerated and identified to species. Data sets were analyzed statistically using one-way analysis of vari-ance for seining and electroshocking for all nine years of the study period. Water quality Water-quality parameters below the hydro during sluicing have been monitored since spring 1989. The parameters monitored were temperature, conductivity, settleable solids, flow volume, and turbidity (as mea-sured by Secchi disc) (Table 1). Temperature and con-ductivity were evaluated with a Yellow Springs Instru-ment (YSI) temperature/conductivity meter. In 1993 and 94 settleable solids were determined with a 1,000-ml graduated cylinder, and in 1995-2001 an Imhoff cone (1000 ml) was used. A one-way analysis of vari-ance test was conducted to determine significant differ-ences between years. RESULTS Annual fall sampling (Table 2) resulted in 13,063 fishes with 26 species. Over the nine years, the species most observed were the sand shiner, Notropis ludibundus (38.6%); red shiner, Notropis lutrensis (34%); and flathead chub, Hybopsis gracilis (12.2%). The catch-per-unit-effort (CPUE) ranged from 0.467 fish/foot to 3.035 fish/foot for a 9-year calculated CPUE of 0.913. There was no significant difference between years for shock-ing (p = 0.4879), seining (p = 0.4879), and total num-bers offish sampled (p = 0.1164). Water quality Daily water temperatures ranged from 7.5 to 22° C, but generally were the same from 1993 to 2001. Dis-60 M. P. Gutzmer et al. Table 1. Water-quality parameters during fall fish-sampling below Spencer Hydro, 1993-2001. 1993 1994 1995 1996 1997 1999 2000 2001 Temperature °C 10.9-16.0 9.6-10.6 8.6-12.2 14.1 18.7 25.7 22 7.5-15.9 Dissolved oxygen 9.61 7.62 8.04-8.76 11.06-11.41 pH 8.9 8.1-8.2 8.5 Secchi disc (cm) 5-20 15 10 23 25 20-22 Settleable solids (mg/l) 5-25 10-20 <10 3 1.5 <1 0.1 0.05 Conductivity (Ilohms) 185-190 249-255 177-184 228 244 210 250-320 256 TDS (Total dissolved solids) 133-138 138 Flow (cfs) (Apr.-Sep. mean) 1914 1500 2686 2019 1915 2005 1440 1887 solved oxygen ranged from 7.62 to 11.41 mg/l. The pH values ranged from 8.1 to 8.9, and Secchi disc readings ranged from 5 to 22 cm through all fish samplings. Settleable solids ranged from 0.1 through 25 mg/l. Con-ductivity ranged from 177 to 320 Il ohms. In the later years ofthe study, total dissolved solids were measured and ranged from 133 to 138 mg/kg. Over the nine-year period, April-September flows ranged from 1440 to 2636 cfs, and the average was 1914 cfs (Table 1), indicating relative stability of sandbed prairie streams. DISCUSSION The species composition was somewhat comparable to that found in previous studies of the river. Hesse and Newcomb (1982) found that sand shiners composed 88.6%, river shiners 10.3%, and bigmouth shiners 1.1% in the downstream river section, below the hydro. For 1993-2001, NPPD surveys indicated that sand shiners and red shiners were the most common, at 38.6% and 34%, respectively. Abundances ofbigmouth shiners were similar to the Hesse studies, with 5.6% of the total sample. Only one river shiner was docu-mented in our studies, but in the early 1980s they composed 20.1% of the catch. Previous studies indi-cated only a few river shiners in some incidental spring sampling, and no apparent adults in the fall were iden-tified (Gutzmer et al. 1996). As in the Hesse studies, some species appeared in samples during certain times of the year and not in others, because certain habitats were much more accessible than others. This was especially true above the hydro because high flows, inclement weather, and oftentimes very different habi-tat types (deeper, marshy, wooded sandbars with inter-mittent isolated or partially connected meandering streams to the river itself) were common for several kilometers. For purposes of this study, only down-stream of the hydro was evaluated for purposes of eliciting any possible barrier/distribution effects or perturbating impacts as a result of sluicing events dur-ing this nine-year period. Among the species identified as sensitive in Title 117, Nebraska Surface Water Quality Standards, is the grass pickerel, Esox amerieanus, which was documented in our collections below the hydro in 1993 and 2000. The yellow perch, Perea flaveseens, was also sampled in 2001 and was a new addition to the species list. Peri-odically collected were recreationally important species such as sauger, Stizeostedion eanadense; largemouth bass, Mieropterus salmoides; and channel catfish, Ietalurus punetatus. Below Spencer Dam is a well-established, recreationally recognized channel catfishery as well as a fall run of sauger that attracts fishermen from across the state. The CPUE estimate for all years combined was 0.913. There were no significant differences between CPUE for any of the years sampled. There was some flow varia-tion, but not enough to significantly impact sampling success or the populations themselves. It appears that species richness remins relatively stable regardless of any hydro activities related to sluicing, at least in the short term. The increased sediment load and loss of acclima-tion time under the low flowlhigher water temperature conditions were once thought to be the major causes of the fish kills and could be detrimental to existing fish populations (Gutzmer 1993). The movement of sedi-ment through the flood and sluice gates can also strand fish above and below the hydro due to shifting stream channels and deposited sediment. The tainter and sluice gates were normally opened quickly and the pond drained rapidly during historic operation of the facility. Operational modifications instituted in the early 1990s, such as monitoring and slowing the rate at which the pond is dropped above the hydro, have been effective in reducing fish mortality. Table 2. Fall sampling abundance, catch per unit effort (CPUE), sampling enumeration, and percent composition offish on the Niobrara River below Spencer Hydro, 1993-2001. Sn = Seine, Sk = Shock. 1993 1994 1995 1996 1997 1999 2000 2001 1993-2001 Sn Sk Sn Sk Sn Sk Sn Sk Sn Sk Sn Sk Sn Sk Sn Sk Totals % Big mouth shiner 19 15 1 1 5 9 27 2 10 12 158 20 2 5 286 2.20 Black bullhead 1 5 1 1 1 9 0.10 Black crappie 1 1 2 0.00 Bluegill 1 6 1 1 8 6 2 2 27 0.20 Brassy minnow 3 1 1 1 1 7 0.10 Carpsuckers spp. 15 1 13 104 4 89 9 65 3 7 5 383 7 18 10 733 5.60 Channel catfish 3 5 47 14 149 92 5 9 50 32 7 42 6 37 11 509 3.90 Common carp 2 7 7 8 2 9 6 7 1 2 51 0.40 Creek chub 2 8 10 0.10 Longnose dace 1 1 0.00 Emerald shiner 1 2 1 36 25 6 71 0.50 Fathead minnow 77 9 2 1 1 1 8 99 0.80 Flathead chub 3 4 26 35 174 569 166 163 46 84 84 89 11 22 10 103 1589 12.20 Grass pickerel 1 1 2 0.00 Largemouth bass 6 1 2 4 1 1 1 2 2 5 1 7 33 0.30 ~ Red shiner 308 382 93 143 439 80 140 80 797 '" 161 491 127 144 409 303 350 4447 34.00 ;:,-River shiner 1 1 0.00 0" '" "-Sand shiner 326 165 198 36 831 547 52 109 355 53 364 182 891 489 176 274 5048 38.60 0 EO Sauger 1 1 1 3 0.00 ~ Shorthead redhorse 4 4 4 1 2 3 1 19 0.10 '" ;:! (') Stone catfish 1 1 2 0.00 '" 'j White crappie 1 1 1 1 4 0.00 t1 ~ White sucker 2 1 1 2 2 8 16 0.10 ~ Yellow bullhead 1 1 5 7 0.10 S· Yellow perch 1 1 0.00 "" ;:,-'" No. ofFish Sampled 755 621 390 264 1720 1315 463 395 1341 362 966 484 1638 1002 550 797 13063 ~ 0 Distance Sampled (ft) 500 1100 700 700 400 600 750 910 750 1155 850 1200 1100 1400 600 1600 14315 0" a CPUE 1.510 0.565 0.557 0.377 4.300 2.192 0.617 0.434 1.788 0.313 1.136 0.403 1.489 0.716 0.917 0.498 a Combined CPUE 0.860 0.467 3.035 0.517 0.894 0.707 1.056 0.612 0.913 100.00 ::tI ~. '" 'j O'l I-' 62 M. P. Gutzmer et al. It appears that with environmentally friendly ways to pass sediment, fish below Spencer Dam survive and express resilience to conditions created by sluicing. Sediments can pose detrimental effects on aquatic eco-systems, but many of the mechanisms for toxicity are still unclear (Waters 1995). In the case of Spencer Hydro and the lower Niobrara River, it may be that the fish present in this river system are highly adapted to periodic high silt load conditions that prevail in sandbed prairie streams. Generally, the species composition has not dra-matically changed, with possible exception of decrease of river shiners from the earlier, Hesse studies. This lower reach of the Niobrara River appears to have fishery populations that have adapted to the annual perturbations caused by sluicing or short-term sedi-ment releases. ACKNOWLEDGMENTS We would first like to thank NPPD for funding this monitoring study. We would also like to thank Brian BareIs and other reviewers for their critical review of this manuscript. A big thanks to Jean Munson for her intitial manuscript preparation. We would also like to thank those who take the time to become aware and informed about the precious natural resources of the Niobrara River and NPPD's efforts to minimize and eliminate any impacts harmful to the indigenous biota there. 78022 LITERATURE CITED Gutzmer, M. P. 1993. Operational modifications of the sluicing activities at NPPD's Spencer Hydro Dam to minimize impacts to the Niobrara River Fishery. Environmental and Natural Resources of the Niobrara River Basin Research Symposium. --, J. W. King, and D. P. Overhue 1996. Environ-mental impacts in the vicinity of Spencer Hydro Power Dam during sluicing activities in the Niobrara River, Nebraska. Transactions of the Nebraska Academy of Sciences 23: 1-8. Hesse, L. W., and B. A. Newcomb. 1982. Effects of flushing Spencer Hydro on water quality, fish, and insect fauna in the Niobrara River, Nebraska. North American Journal of Fisheries Management 2: 45-52. Hotchkiss, R. H., X. Huang and M. P. Gutzmer, 1993. Achieving a sediment balance across dams; step-ping up a technology. Environmental and Natural Resources of the Niobrara River Basin Research Symposium. Mares, P. E. 1991. Feasibility of modeling regional reservoir sedimentation: numerical approach. Mas-ters Thesis, University of Nebraska-Lincoln. Waters, T. F. 1995. Sediment in streams: sources, biological effects and control. Bethesda, Maryland, American Fisheries Society Monograph 7: 251 pp. 

FISH SPECIES-RICHNESS TRENDS IN THE NIOBRARA RIVER, NEBRASKA, BELOW THE SPENCER DAM

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FISH SPECIES-RICHNESS TRENDS IN THE NIOBRARA RIVER, NEBRASKA, BELOW THE SPENCER DAM

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