This document summarizes findings from an OECD study on groundwater use policies in agriculture. It finds that groundwater irrigation accounts for 33% of total irrigated land and 56% of withdrawals in OECD countries. Intensive pumping can cause negative externalities like stream depletion, salinity, and land subsidence. Countries take diverse regulatory approaches from direct controls to economic instruments to collective management. Regions with less management experience higher groundwater use and stress. The study recommends a "tripod approach" for intensive use regions, involving entitlement systems, economic instruments, and collective management to move towards sustainability.

1. WHAT POLICIES TO MANAGE
GROUNDWATER USE IN AGRICULTURE?
Findings from a study on OECD countries
Guillaume Gruère
Senior Policy Analyst
Natural Resources Policy Division
OECD Trade and Agriculture Directorate

2. 1. Groundwater: a great asset for
irrigators
• OECD in 2010: 23mha
of groundwater irrigated
land (33% of irrigated
land) and 123.5km3/yr
(56%) of groundwater
withdrawals for irrigation
• Increasingly used in
irrigation-prone regions
of large groundwater
using countries
Trends in use for top 10 OECD groundwater irrigators
US  Greece 
Mexico  Japan 
Turkey  Australia 
Italy ? Korea
Spain  Portugal ?

3. • Three significant negative externalities of intensive pumping:
– Stream depletion
– Salinity
– Land subsidence
but linked with significant challenges
Dr J. Poland’s picture of land subsidence in Mendota, San
Joaquin Valley, California, USA, 1925-77.

4. • When to intervene?
– Groundwater is often lying
between private property and
common pool resources
– Argue that there may be a
justification for long term
depletion, and to cope with
negative externalities
• What instrument to use?
– No single solution…
2. What does economics tell us?

5. 3. What policies and management
approaches are used in OECD countries?
Direct and indirect, intensive and extensive
regulatory approaches
Economic approaches: pricing, markets, and others
Collective management approaches Supply-side approaches

6. Does this diversity reflect groundwater constraints?
Evidence based on 20 OECD agricultural regions
Relative agro-climatic and other groundwater stresses
Relative
importance of
public
management
approaches
• Systematic comparison and pairwise correlations suggest:
– Regions that exercise less control on groundwater <->higher use and demands
– Economic and supply-side approaches <-> higher groundwater stress
• Still no overall correlation between scope of management and
importance of groundwater stresses

7. 4. What should be done to move
towards sustainable systems?
ALL GROUNDWATER IRRIGATION SYSTEMS
6 general conditions:
Robust information system Favour demand-side instruments
Use groundwater conjunctively Enforce existing regulations first
Favour use of direct approaches Remove perverse incentives
REGIONS WITH INTENSIVE GROUNDWATER USE
A Tripod Approach
1. Entitlement systems and regulations
2. Economic instruments 3. Collective management
REGIONS WITH HIGH STRESS
A) Agronomic tools B) Supply-side instruments

8. Thank you for your attention
• Reference:
OECD (2015), Drying wells, rising stakes: Towards
sustainable groundwater use in agriculture, OECD
Studies on Water, OECD Publishing, Paris.
http://dx.doi.org/10.1787/9789264238701-en
• Websites: http://www.oecd.org/tad/sustainable-
agriculture.htm
– www.oecd.org/water
• Email: Guillaume.Gruere@oecd.org