Menu
cow on hill cow on hill

Improving Lake Rotorua water quality

To protect Lake Rotorua for generations to come, we need to reduce the amount of nutrients entering its waters.

Over time, nitrogen and phosphorus from the surrounding catchment have built up in the lake. These nutrients come from both natural and anthropogenic (manmade) sources. In the past, treated sewage and nutrient leaching from lakeside septic tanks contributed heavily to the problem. Today, while sewage is now better managed with advanced treatment and community reticulation, nutrient loss from farming in the wider catchment remains a challenge. 

What happens on the land has a major impact on water quality. Without careful management, nutrients can seep into the soil or run off into streams and rivers, eventually reaching the lake. This fuels the growth of algae and cyanobacteria (sometimes called blue-green algae), which can lower water quality and, in some cases, be toxic. 

To leave the lake in a better state for the future, we’ve set an ambitious goal – prevent 320 tonnes of nutrients from entering Lake Rotorua each year. 

To achieve this, we’ve developed an Integrated Framework – a set of tools that includes land use rules, financial incentives, gorse management and engineering solutions. 

The Integrated Framework

Here’s how it breaks down: 

  • Initial nitrogen load : 755 tonnes/year
  • Target nitrogen load: 435 tonnes/year 
  • Reduction required: 320 tonnes/year 

We aim to reach this target through: 

  • Planning rules for pastoral sector: 140 tonnes 
  • Financial incentives: 100 tonnes 
  • Gorse management: 30 tonnes 
  • Engineering solutions: 50 tonnes 

Together, these actions will help us reach a sustainable nitrogen load of 435 tonnes per year by 2032 and ensure Lake Rotorua stays healthy for future generations to enjoy. 

More information

If you're a rural landowner in the Lake Rotorua Catchment with more nitrogen allocation than you need for your farming operation, you may be eligible to sell it through the Lake Rotorua Incentives Scheme. 

The scheme was created to remove 100 tonnes of nitrogen per year from entering Lake Rotorua. This is through the purchasing of nitrogen from landowners who voluntarily reduce their nitrogen loss below what’s allowed under the Lake Rotorua Nutrient Rules. 

Lake Rotorua Incentives Scheme Policy 2024 

How it works 

The scheme is a voluntary, private agreement between the landowner and a Bay of Plenty Regional Council negotiator. To help get you started, the Rotorua Lakes Programme will cover the cost of a farm consultant to assess how much nitrogen you may be able to sell. 

If you decide to go ahead, we’ll provide the necessary documents and recommend you talk them through with your lawyer. Once everything is signed and any required land use changes are made, payment will be transferred directly to your bank account. 

Who can apply 

Any rural landowner in the Lake Rotorua Catchment – no matter the size of the property – who has excess nitrogen may be eligible to take part. 

The scheme has recently been extended beyond its original 2022 deadline, giving landowners more time to consider their options. 

If you're thinking about selling nitrogen, or just want to chat through what's possible, get in touch with us on 07 921 3377 or email Rotorua.Lakes@boprc.govt.nz – we're here to help. 

Gorse is a nitrogen-fixing plant, which means it pulls nitrogen from the air and turns it into a form that helps plants grow. But research shows gorse produces more nitrogen than it needs, and this extra nitrogen can leach into groundwater and eventually make its way into our lakes. 

Too much nitrogen in the water fuels algal blooms and the growth of nuisance cyanobacteria, which harms water quality and the overall health of the lake. 

Put simply, gorse is a stubborn weed that doesn’t improve land productivity or the environment. It’s also tricky to get rid of — if it’s not managed properly after clearing, it’s very likely to grow back. 

Land use changes 

The Bay of Plenty Regional Council has finalised 10 gorse agreements with Rotorua landowners, helping convert 267 hectares of gorse into productive, low-leaching land uses. In addition, another 190 hectares of gorse have been controlled through incentives agreements. 

Even if all landowners voluntarily adopt good practice, reaching our goals requires rules that limit nitrogen loss from pastoral land. These are set out in the Lake Rotorua Nutrient Management Rules, or Plan Change 10. 

Plan Change 10 requires the Council to review the science behind the land management rules and sustainable targets every five years. These reviews are detailed in the Plan Change itself and supported by an agreement with key stakeholders, including The Lakes Water Quality Society and the Rotorua Pastoral Collective. 

The most recent review, completed in 2022, is presented in 12 technical reports along with a summary document. All reports, including the summary, were independently peer-reviewed by Professor Warwick Vincent from Laval University, Canada. 

Relevant links

Rotorua Te Arawa Lakes Programme
Nutrient management rules