Catchment pathways and mitigations at the land/water interface

Issues vary among catchments B C Nutrient issues: A > B > C Sediment issues: B > A > C Pathogens issues: B > C > A

How “stuff” was getting into WW streams with water Pasture & track runoff (Sed, N, P bugs) Groundwater, seeps (N&P) with sediment (bugs, P) Erosion, streambank damage stock dung & urine (bugs, N & P) fertiliser application (P)

N and P Pollutant Forms Key sources Nitrogen (1) urine patches, (2) fertiliser, (3) effluent irrigation Phosphorus (1) fertiliser, (2) soil erosion, (3) animal excreta/effluent irrigation total nitrogen (excluding nitrogen gas) organic nitrogen inorganic nitrogen dissolved particulate ammonium nitrite nitrate Note: total Kjeldahl N = organic N + ammonium total phosphorus dissolved/ soluble / filterable (<0.45 µm) particulate reactive organic inorganic

Sediment Aggregate Floc (1) grazed pasture, (2) stream bank/bed erosion, (3) animal excreta, (4) animal tracks, (5) unpaved roading suspended sediment organic mineral clay silt Aggregate Floc Source: Droppo et al. (2005) Source: Liss et al. (1996)

Faecal microbes Crytosporidium Rotavirus Campylobacter (1) grazed pasture, (2) effluent irrigation, (3) wild and feral animals, (4) livestock in, or close to waterways faecal microbes viruses bacteria protozoa Indicator: enteroviruses, phages Pathogens: human enteroviruses and adenoviruses, noroviruses, rotaviruses, hepatitis A Indicator: E. coli Pathogens: E. coli, Campylobacter, Salmonella Indicator: Clostridium perfringens spores Pathogens: Giardia, Cryptosporidium Crytosporidium Rotavirus Campylobacter

With the water? surface runoff subsurface floodplain inundation infiltration excess saturation excess subsurface groundwater seepage matrix flow – slow preferential flow – fast e.g. tile drains floodplain inundation hyporheic exchanges Artificial drainage Flooding Surface runoff Seepage Hyporheic exchanges continuous Subsurface flow Stream Groundwater flow

Hill-land sources P fertiliser P to stream P N in urine N as gas Rock mineral P N in urine N as gas Leached N Atmospheric N N fixation N slips & soil erosion bank & gully erosion Runoff livestock excreta sediment bugs

Sediment systems diagram- Hill farms Goals

Nutrients systems diagram – Hill farms Goals

Lowland sources dairy effluent irrigation or discharge sediment, N, P, bugs P, N fertiliser runoff sediment, N, P, bugs N fixation N in urine leached N drains sediment, N, P, bugs

Pastoral mitigation toolbox match land use to capability trees vs livestock vs fodder crops livestock type/system nutrient management budgets, timing, targeting, DCD?; soil carbon target farm hotspots (80/20 rule) e.g. erosion control tree planting raceway/track runoff managed fence seeps and wetlands treatment wetlands on tile drains & catchment outlets grass filters/hedges in swales wintering pads/herd shelters dairy effluent treatment, storage and irrigation riparian setbacks for cultivation fish-friendly culverts & flood gates riparian management

Livestock exclusion fencing Maths: dairy cow faeces/urine inputs 0.3 kg P/ha/y (20% Toenepi yield) 4 kg N/ha/y (13% Toenepi yield) 50 kg SS/ha/y (30% Toenepi yield) 10 billion E coli/ha/y input Plus Bank erosion Sediment re-entrainment Vegetation damage 5 Catchment studies-Before and after exclusion SS loads – 30-90% reductions mostly attributed to reduced erosion E. coli conc. 30-65% reductions nutrients variable Williamson et al., 1996; Owens et al. 1996; McKergow et al., 2003; Line et al. 2000, 2003; Meals & Hopkins 2002, 2003.

Resuspension fine material re- entrained cattle entered stream 50 100 150 200 250 00:00 04:48 09:36 14:24 19:12 Time (24 h) Turbidity(NTU) Upstream Downstream cattle entered stream fine material re- entrained Stassar and Kemperman, 1997

Damage +5 y +3 y Matarawa and Waikakahi

NZ reach scale studies (a small sample)

Buffers & contaminants Filtering surface runoff RIPARIAN ZONE LIVESTOCK STREAM RIPARIAN ZONE LIVESTOCK STREAM Filtering subsurface flow Stream bank stabilisation RIPARIAN ZONE LIVESTOCK STREAM RIPARIAN ZONE LIVESTOCK STREAM Setback

Performance comparison Riparian fencing Subsurface flow filtering Grass filter strips 0 10 30 50 100 % low medium high sediment phosphorus nitrogen Seepage wetlands

Generalised widths to provide riparian functions 0 5 10 15 20 25 30 livestock excreta/damage fish habitat bank stabilisation flood control shade leaf input overland flow filtering wood input plant nutrient uptake wildlife habitat After: Dosskey et al. (1997)

Generalised vegetation types and Riparian functions Grass /sedge Shrubs Trees Bank stabilisation low high Overland flow filtering sediment & sediment bound medium soluble Nutrient uptake - Denitrification med ium Shading Wood input Leaf litter input Enhancing fish habitat Sp. specific Controlling downstream flooding Human recreation Aesthet ics Modified from Dosskey et al. 1997 & Yuan et al 2009

Riparian costs (incl. labour) & some direct benefits Farmer benefits Avoid stock loss, ease management Paddock subdivision Better farm water Stock browse medicinal plants e.g. flax Shelter Aesthetics Timber, carbon credits…. Bridges and crossings Culverts $2,500-$25,000 ea1 Bridges several $ 1000 ea Fencing – Dairy2 single wire electric $2-3/m 3 wire electric $5/m Fencing – Sheep & beef2 wire post + batten $18/m Alternative water supply Variable, big issue in hills sheep/beef Planting with trees/shrubs $1200/ha pines to $10-20,000/ha natives3 Lost farm land Loss of 1 cow at $1000 = cost of fencing 325 m of both sides of stream with single wire electric and 100 m with 5 wire post and batten fence 1 http://www.mfe.govt.nz/publications/land/culvert-bridge-oct04/html/page2.html 2 http://www.ew.govt.nz/enviroinfo/land/management/runoff/costing.asp 3 including labour Quinn et al. 2006. Cheaper from seedlings and incentives available in some regions

Targeting livestock fencing cattle and deer > sheep small streams highly accessible FW tidal inanga spawning sites lake and estuary margins wetland seeps – especially cattle and deer

Whatawhata headwater expt: 36% pine exclude cattle (not sheep) + poplars Reduced temp and macrophytes Increased clarity, wood cover and invert health 2002 2011 Quinn et al. (2009). NZJ Mar FW Res 43(3): 775-802.

6. Riparian reforestation Natural forested habitat Fish cover Wood Microclimate Shade control of stream temp Shade control of algae Natural food resources Enhances biodiversity Terrestrial & aquatic Faster in smaller streams 2002 2011

Riparian forest regrowth cools small streams faster than large ones 10 10 B A Summer Max Summer Max Rate of decline in average summer temperature difference from reference (˚C/yr) 1 1 Summer Mean Summer Mean 0.1 10 100 1000 10000 1 10 100 Catchment area (ha) Channel width (m) Source: Quinn & Wright-Stow 2008

Dairy effluent management Ox ponds need high dilution Mudstone geology low diln in summer Wetlands polish somewhat# SS c. 40-65%, BOD 35-50%, N 15–35%, E. coli 80% Advanced Pond System 50% lower N, P, BOD than 2 ponds; 100-1000-fold more E. coli removal Deficit irrigation best if* low rate, even spread application over wide area, Code of Prac used storage during wet on heavy soils #Tanner and Kloosterman 1997 http://www.niwa.co.nz/sites/default/files/import/attachments/st48.pdf *Monaghan, Houlbrooke et al. (2010). NZJAgRes53: 389-402.

MITIGATING direct FDE losses with deficit irrigation Source: Dave Houlbrooke, AgResearch

Stock & headwater wetlands cattle grazing of small/shallow wetlands high E. coli load, especially in storms (6M/100 ml) increases N exports tracks/ channelisation BUT grazing by sheep may stimulate plant growth

Taupo wetland & cattle 1700 m2 grass, rushes, sedges Exports baseflow 32 g TN/d cattle 306 g TN/d cattle 9% of time => 34% of TN export

Headwater wetland benefits at Whatawhata: 1. trap sediment 10 100 Native forest Pasture HW wetlands Pasture no wetands SS (g/m3)

Whatawhata wetland Mean & S.D Inflow Outflow Inflow Outflow Wetland: 60 m2 grazed headwater wetland 9 ha catchment mean Q = 0.4 l/s Mean & S.D Inflow Outflow Inflow Outflow

Stock & headwater wetlands cattle grazing of small/shallow wetlands high E. coli load, especially in storms (6M/100 ml) increases N exports tracks/ channelisation BUT grazing by sheep may stimulate plant growth

3. Artificial wetlands Tile drains Outlets of small catchments 1-5% of catchment N 20-50% SS ca.80% E. coli ca.90% low P retention Lake Okaro inflow wetland Tanner, et al (2010). NZ guidelines: Constructed wetland treatment of tile drainage. http://www.niwa.co.nz/our-science/freshwater/tools/tile-drain-wetland-guidelines McKergowet al (2007). Stocktake of diffuse pollution attenuation tools...http://www.niwa.co.nz/sites/default/files/import/attachments/stocktake-v10.pdf.

4. Grass filter strips band of managed grass that provides a buffer between a source and a water body

what makes a GFS work? barrier dense vegetation causes runoff to pond and deposit material dense vegetation slows water and creates tortuous paths sieves runoff unsaturated uncompacted soils allows infiltration to occur

GFS & pasture runoff Waikato (Smith, 1989) 200 150 100 50 Particulate P (mg m-3) 50 100 150 1500 1000 500 Nitrate (mg m-3) Particulate N (mg m-3) 25 50 75 SS (g m-3) Grazed no filter Grazed with grass filter (6% of hillslope)

Matching GFS form with purpose and location paddock-edge GFS filter surface runoff lower paddock boundary contour GFS filter surface runoff mid paddock (strip grazed pasture) grass hedge intercept concentrated flow and filter surface runoff concentrated flow paths

How wide: GFS widths for SS control Modelled# as Fn of slope angle & length, soil clay content and drainage: low (<7%) slopes, GFS widths of mostly 1-5% of hillslope predicted to remove 80-95% SS med (7-20%) slopes, widths 2-15% of hillslope - remove 50-95% SS International review*: 5m usually removes 80% SS #Collier et al. 1995 http://www.doc.govt.nz/upload/documents/science-and-technical/riparianzones2.pdf *Yuan, et al . (2009).. Ecohydrology 2(3): 321-336.