To help you identify contaminant risks in your FWFP and create an action plan to reduce contaminants from entering freshwater bodies, a description of key contaminants is provided below. 

• Nitrogen (N) is an important nutrient in all natural systems and is therefore added via fertilizers to increase crop productivity. However, if N is overapplied, not all if it will be used by crops. Any excess N may enter local watercourses which may lead to increased growth of algae and macrophytes. This can lead to nuisance blooms of potentially toxic algae and to low oxygen concentrations once the blooms die that can create dead zones in which fish and other species cannot survive. In freshwater, Nitrogen exists as nitrite-nitrogen and ammoniacal -nitrogen, two forms that can become toxic at concentrations of 3.5 mg/L and 0.4 mg/L respectively and can cause direct harm to fish and macroinvertebrates.[1] 
• Phosphorus (P) is also a limiting plant nutrient that is needed to maximise plant growth, but excess concentrations can lead to growth of nuisance algae and macrophytes. 
• Total phosphorus (TP) is a measure of all types of phosphorus present in the water column. Including phosphate bound to suspended sediment and Dissolved Reactive Phosphorus (DRP) which is more readily available for plants.  
• E. coli is a bacterium that is present in the digestive tract of all warm blooded organisms, including cattle, birds and humans. It is therefore naturally present in soils and water. The concentration of E. coli in freshwater is used to infer the risk of humans becoming sick after ingesting water. As a guide, a concentration of 540 E. coli/100 ml indicates a campylobacter infection risk >5%. At this concentration, recreational activities in water should be avoided [10].  
• Sediment - as rainwater flows over land it can mobilise different sized particulates of substrate that are then transported to a waterbody. Sediment can fill up the small spaces between rocks and make the habitat unsuitable for fish and macroinvertebrates to live in. 

Inherent risks (vulnerabilities) 

• Steep slopes (sediment loss, erosion, and contaminant leaching and runoff) 
• Low slope areas (intensive) 
• Stony river flats (porous, flood risk)  
• Critical source areas 
• Adverse events/ climate change 
• Soil type – heavy soils (runoff), free draining soils (leaching) 
• Contaminant pathways e.g., drainage, ephemeral streams/ high rainfall 
• Low rainfall (drought), high rainfall (contaminant runoff) 
• Irrigation. 
• Sub-surface drains. 
• Areas of cultural significance. 

Potentially risky activities 

• Intensive winter grazing, feedlots, stockholding areas 
• Intensification eg forest-pasture, sheep&beef-dairy 
• Silage pits, offal/rubbish pits 
• Fert application 
• Stock access to streams, wetlands 
• Stock and mechanical activity (cultivation, spraying, irrigation, drainage) near waterways 
• Fish passage impediments 
• Water takes and use.  
• Irrigation 
• Point sources – tracks, gateways, troughs, yards, barns, silage pits, dumps 
• Hazardous substances like fertiliser and agrichemicals – storage, use, disposal 
• Effluent storage and management, discharge 

Mitigations 

• No tillage 
• Low fert/ fert management 
• Animal numbers, stocking rates 
• Strategic grazing/ cropping and paddock planning (IWG regs compliance) 
• Manage CSAs and drains 
• Precision ag (fert, irrig) 
• Follow GMP and codes 
• Stock exclusion, fencing and riparian planting, grass buffers of waterways and wetlands (SE regs compliance) 
• Wetland restoration 
• Processes and procedures (e.g. staff training) 
• Retiring land (and earn C credits or biodiv credits if eligible) allow to revert or do some planting 
• Fence off native remnants 
• Polar and willow pole planting strategically, e.g. above fencelines and tracks, and in the most eroding areas 
• Water table and irrigation codes compliance (water measurement regs, resource consents) 
• Effluent discharge management 
• Irrigation management 

Benefits 

• Water quality improvements 
• Keep nutrients on farm, reduce erosion 
• Animals safer (from dangerous areas) 
• Market assurance 

In your farm plan you will need to talk about vulnerabilities and risks to water quality. The below table shows more information on the link between soils and the risk to water quality. To use the table below, look at the properties of your soil from the soil information in the mapping tool, your topography and then the risk to water quality in the table. This will then help you to think about the level of risk to water quality on your farm and on farm actions to reduce these risks. 

Table 1: Link between soil characteristics and potential risks to water quality [6]