Managing Creek Pastures for Improved Water Quality


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Runoff of E. coli and other fecal indicator bacteria from grazing lands has been identified as a significant source of bacterial contamination in need of reductions to improve water quality. Improved management of creek pastures and implementation of on-farm best management practices to address these bacterial issues is critical to the success of watershed restoration efforts. To address this, the impacts of grazing management and providing alternative off-stream water in creek pastures were evaluated to assess their effectiveness for reducing E. coli loading.

Presentation by: Kevin Wagner

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  • You might not have realized it, but bacteria is the #1 cause of water pollution in Texas. In fact, more than 50% of the impairments in Texas are due to excess bacteria levels. But, you would never know it. While some water pollution is often easy to detect, bacteria pollution is not. A waterbody choked with algae, a muddy river loaded with sediment, or a lake covered with an oily sheen all exhibit clearly noticeable impairments. Bacteria in water, on the other hand, are not at all noticeable to the naked eye.
  • No difference in E. coli concentrations at ungrazed, proper grazed & heavy grazed pasturesNo correlation between stocking rate & E. coli concentrations
  • Significant correlation between E. coli concentration & cattle presence during runoff eventAt all grazed sites, I found that the highest E. coli concentrations occurred while the sites were stocked.At BB2, conc 88% lower when destockedThis appears to be the primary factor determining E. coli conc from my sitesAt BB3, conc 98% lower when destockedAt SW17, conc 99% lower when destocked
  • E. coli levels in runoff declined rapidly after rotationLevels reach background levels within 1 month (typically 2 wks)Background E. coli levels were SIGNIFICANTMedian E. coli levels at ungrazed & destocked sites ranged from 3,500 to 5,500 cfu/10080-99% of loading from 3 sites in 2009 was from wildlife
  • To summarize my findings from Objective II, my study indicatesthat the timing…
  • Found 57% reduction in EC load (on animal unit basis) however NSD due to highly variability
  • Background E. coli levels were considerable and relatively consistent across all sites, with median levels typically ranging from 3,500 to 5,500 cfu/100 mL. Most existing water quality modeling efforts, TMDL projects, and other watershed assessment and planning efforts do not take background E. coli levels into account. However, because background concentrations have been found by this study and others (Guzman et al. 2010) to be a significant component of total E. coli in runoff, especially as time lag between fecal deposition by livestock (i.e. grazing event or manure or litter spreading) and runoff event increases, this source should be considered as a separate source when allocating loads and assessing load reductions
  • Managing Creek Pastures for Improved Water Quality

    1. 1. Kevin Wagner, Terry Gentry, LarryRedmon, Daren Harmel, Jamie Foster, RobertKnight, Allan Jones
    2. 2.  More than 50% of impairments in Texas are due toexcess bacteria levels.Background
    3. 3. AvianWildlife7%Sewage11%AvianLivestock1%Cattle22%Non-AvianLivestock12%Non-AvianWildlife29%Unknown10%Pets8%Major sources of bacteriaLeon River Peach CreekLeon River010203040506070Domestic Sewage Pet Cattle Other Livestock Wildlife UnidentifiedSourceContributions(%of200isolates)
    4. 4. Exclusionary FencingFecal ColiformReductionReference30% Brenner et al. 199441% Brenner 199666% Line 2003 Eliminates cattle access to streams Expensive to construct & maintain Often not feasible to fence-offentire stream, i.e. rangeland Fencing of streams not accepted bymany landowners
    5. 5. Management of CreekPastures is CriticalReduce cattle’s time in &near streamMaintain ground cover withproper grazing management
    6. 6.  5 yr study on: Proper grazing management Alternative water supplies Alternative shade Conducted by: Texas AgriLife Extension Service Texas AgriLife Research Texas Water Resources Institute USDA-ARS Funded by: Texas State Soil and Water Conservation Board USDA Natural Resources Conservation Service US Environmental Protection AgencyGrazingland Research
    7. 7. Grazing Management Evaluation Seven 1 ha sites assessed across 3 locations 3 – ungrazed 3 – properly stocked 1 – stocked @ 2 X recommended rate Grazed sites were rotationally grazed Flow measured w/bubble flow meter V-notch weir H-flumes Sample Collection Automated samplers
    8. 8. Grazing management effectson E. coli runoffGrazing Management Stocking RateUnstocked Properly stocked Heavy stockedE.coliConcentration(cfu/100mL)1e+11e+21e+31e+41e+51e+61e+71.E+011.E+021.E+031.E+041.E+051.E+061 10 100 1000E.coliConc.(cfu/100mL)12 Month Stocking Rate (ac/AUY)UngrazedCultivated Cultivated withgrazed pastureGrazedpastureE.coli(cfuper100mL)110100100010000100000Outlier90th75thMedianMean25th10th
    9. 9. Comparison of E. coli LevelsWhile Sites Stocked & DestockedCultivated Cultivated withgrazed pastureGrazedpastureE.coli(cfuper100mL)110100100010000100000Outlier90th75thMedianMean25th10th
    10. 10. Why no correlation btwn E. coli& grazing management?Rapid decline following rotation Significant background levels
    11. 11. Why no correlation btwn E. coli& grazing management?80-99% of loading from wildlifeat 3 sites in 2009Date BB1 BB2 BB33/13/09 1403/25/09 1,2003/26/09 1,000 7,2003/27/09 2,0004/17/09 1,155 980 4504/18/09 4,400 2,225 2,1004/28/09 7,600 12,200 24,00010/4/09 57,000 5,114 3,06510/9/09 36,000 24,043 15,00010/13/09 42,851 23,826 5,59110/22/09 172,50010/26/09 261,000 181,000 45,000
    12. 12.  Rotationally graze creek pastures Target grazing of creek pastures to dry periods Rotate cattle to upland pastures during wet periods 88-99% reductions in edge-of-field runoff of bacteriafrom creek pastures potentially achievableManagement Implications
    13. 13. Alternative Water EvaluationBi-monthly water sampling & quarterly GPS tracking
    14. 14. Alternative water effectivenessReduction inTime Spentin StreamReference43% Wagner et al. 201285-94%Miner et al. 1992Clawson 1993Sheffield et al. 1997
    15. 15. E. coli Load (cfu/AU/day)-57%43%Reduction
    16. 16.  Sheffield (1997) also found: 77% decrease in sedimentation 90% decrease in suspended solids 54% decrease in nitrogen 81% decrease in phosphorusAlternative Water SourceBacteria Reduction Reference85-95% (EC) Byers et al. 200551% (FC) Sheffield 1997
    17. 17. Shade StructureGPS Collar EvaluationTime Spent w/in 25’ of Stream Reference27% Reduction Wagner et al. 2012 Shade, coupled withalternative water &salt/mineral locations,encourages cattle tospend less time inriparian areas.
    18. 18. Conclusions Rotate cattle to uplandpastures during wet periods Promote loafing, drinking &grazing away from creeks Alternative water supplies Additional shade Proper grazing management Be aware of impacts ofbackground/wildlife sources
    19. 19. Kevin Wagner, PhDklwagner@ag.tamu.edu979-845-2649 Provided By:TSSWCB, EPA & USDA-NRCS