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Shallow lakes restoration review: A literature review

TR 2018/13
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Report: TR 2018/13

Author: Jonathan Abell (Ecofish Research Ltd)

About this report

Shallow lakes are important resources to the Waikato region. These ecosystems have generally been degraded due to multiple causes, particularly eutrophication which is increased productivity due to pollution by the nutrients nitrogen and phosphorus.

Waikato Regional Council has developed a Shallow Lakes Management Plan to guide the restoration of shallow lakes in the region. Identifying cost-effective approaches to improve water quality in shallow lakes that have been degraded by eutrophication requires good understanding of the range of lake restoration methods that are part of the ‘toolbox’ available to decision makers and managers. This literature review is therefore intended to provide context to support environmental management of shallow Waikato lakes.

The objective of this review is to synthesise and evaluate the current literature relating to approaches to restore shallow lakes degraded by anthropogenic eutrophication. Particular focus is given to quantifying the performance of individual approaches based on the results of robust monitoring studies described in the primary scientific literature.

The review considers studies undertaken worldwide, with particular focus on lakes in temperate regions that have been degraded due to nutrient pollution from agricultural land, with implications for Waikato lakes highlighted where relevant.

Read or download the report

Shallow lakes restoration review: A literature review [PDF, 1.8 MB]

Contents
1 Introduction
2 Overview of Waikato shallow lakes
2.1 Setting
2.2 Current water quality
2.3 Current approaches to restoration
3 Eutrophication in shallow lakes
3.1 Nutrient sources
3.2 Sediment fluxes
3.3 Alternative stable states
3.4 Invasive fish
4 Drivers of lake restoration
4.1 International
4.2 National
4.2.1 Policy drivers
4.2.2 Legislation
4.2.3 Funding
4.3 Regional
4.3.1 Waikato Freshwater Strategy
4.3.2 Proposed Waikato Regional Plan Change
4.3.3 Waikato River Clean-Up Trust
4.3.4 Shallow Lake Management Plan
5 Techniques to address eutrophication in shallow lakes
5.1

Overview
5.2 Controlling external nutrient loads
5.3 Controlling internal nutrient loads
5.3.1 Overview
5.3.2 Dredging
5.3.3 Sediment capping
5.3.4 Phosphorus adsorption and flocculation
5.4 Biomanipulation
5.4.1 Fish
5.4.2 Bivalves
5.4.3 Macrophyte harvesting
5.4.4 Floating wetlands
5.4.5 Algicides
5.4.6 Macrophyte re-establishment
5.5 Hydrologic manipulations
5.6 Emerging technologies
6 Case studies
6.1 Overview
6.2 35 lakes: Reductions in external nutrient loads
6.3 36 Danish lakes: Biomanipulation of fish communities
6.4 Lake Apopka, USA: reduction of external phosphorus load from agriculture
6.5

Barton Broad, England: External load reduction and dredging
6.6 City Park Lake, USA: dredging and point source reduction
6.7 Lake Finjasjon, Sweden: external load reduction, dredging and biomanipulation
6.8 Lake Kraenepoel, Belgium: dredging, external load reduction and biomanipulation
6.9 Loch Leven, Scotland: External load reductions
6.10 Minneapolis Chain of Lakes, USA: storm water treatment and alum dosing
6.11 Lake Rotorua, Bay of Plenty, New Zealand: Reductions in external loads and alum dosing
7 Impediments to shallow lake restoration
7.1 Overview
7.2 Insufficient reductions to external nutrient loads
7.3 Lags
7.4 Hysteresis
7.5 Delayed macrophyte re-establishment
7.6 Climate change
7.7 Need for lake-specific approaches
7.8 Social and political challenges
8 Conclusions
8.1 Overview
8.2 Answers to research questions
8.3 Next steps to consider
References