Valuation of agricultural impacts on rivers and streams using choice modelling: A New Zealand case study

Figures & data

Table 1  Attributes and levels used in choice sets.

Attributes	Base level	Improvement levels
Health risk	60	10 and 30 people sick from contact recreation per 1000 per year
Ecology	Poor	Fair and good
Flow conditions	5	1 and 3 months of low-flow conditions per year
Cost	$0	$15, $30, $45, $60, $75, $90 per household per year

Table 2  Ecology attribute level definitions.

Quality	Definition
Poor	• Weeds are the only aquatic plants present and cover most of the stream channel
	• Stream-bed covered mostly by thick green algae mats
	• Only pollution-tolerant insect populations are present
	• No fish species are present.
Fair	• About 50% of stream channel covered by plants
	• Few types of aquatic plants, insects or fish
	• Algae covering about 20% of stream bed
	• Population densities reduced
Good	• Less than 50% of stream channel covered by plants
	• Algae cover less than 20% of stream-bed
	• Diverse and abundant range of aquatic plants, fish and insects
	• Insect communities are dominated by favourable species, with pollution-sensitive populations present

Figure 1  Example choice set.

Table 3  Agri-environmental attitudes and river and stream resource importance.

	Attitude (% of sample)
	Disagree strongly	Disagree		Agree		Agree strongly		Don't know
Agri-environmental attitude
Agricultural production today is environmentally safe	21	48		20		4		7
Canterbury ratepayers as a whole should pay the costs of cleaning up and preventing agricultural impacts on water resources	3	22		35		29		11
Farmers should pay for the costs of cleaning up and preventing agricultural impacts on water resources	3	10		43		41		3
The agricultural landscape is important in Canterbury	2	2		41		54		1
A price should be charged for water for irrigation	5	13		43		32		7
Agriculture should fully convert to organic farming methods	13	43		21		12		11
River and stream resource importance
Resource for future generations	88		—		—		—
Habitat for plants and animals	83		—		—		—
Recreational opportunities	75		—		—		—
Drinking water resource for public	74		—		—		—
I just like knowing that they are there	28		—		—		—
Resource for commercial development	14		—		—		—

Table 4  Model data summary.

Variable	Description
Attribute variables
Risk 10	10 people per 1000 per year sick from recreational contact
Risk 30	30 people per 1000 per year sick from recreational contact
Ecology good	Ecological quality is good
Ecology fair	Ecological quality is fair
Flow 1	1 month of low-flow conditions per year
Flow 3	3 months of low-flow conditions per year
Cost	$15, $30, $45, $60, $75 and $90 per household per year
Non-attribute variables
ASC	Alternative specific constant: 1 if alternative 2 or 3; 0 if base alternative
Safe	Respondent agrees that agriculture is environmentally safe
Commercial	Respondent indicates that commercial use is important
Farmers pay	Respondent indicates that farmers should pay for agri-environmental water policy
Income	Household gross yearly income
Gender	1 if respondent female; 0 if male

Table 5  Random parameter logit model estimates.

	Parameter estimate (standard error)
Attribute
Risk 10	0.592 (0.066)^3
Risk 30	0.072 (0.058)
Ecology good	0.805 (0.078)^3
Ecology fair	0.356 (0.681)^3
Flow 1	0.346 (0.074)^3
Flow 3	0.032 (0.085)
Cost	−0.016 (0.002)^3
Non-experimental variables
ASC	0.086 (0.337)
ASC^*Safe	−1.229 (0.208)^3
ASC^*Commercial	−1.071 (0.293)^3
ASC^*Farmers pay	−0.945 (0.058)^3
ASC^*Gender	−0.518 (0.204)^2
ASC^*Income	0.179 (0.048)^3
Standard deviation of parameter distributions
Risk 10	0.592 (0.066)^3
Risk 30	0.072 (0.058)
Ecology good	0.805 (0.078)^3
Ecology fair	0.356 (0.681)^3
Flow 1	0.346 (0.074)^3
Flow 3	0.032 (0.085)
Cost	0.016 (0.002)^3
Log-likelihood	−1410
McFadden psuedo-R ^2	0.37
AIC	1.35
BIC	1.39
Pr(chi^2) > z	0.000
Iterations	22
Observations	2160
^1Significant at 10% level
^2Significant at 5% level
^3Significant at 1% level

Table 6  Estimates of average WTP ($NZ 2008). Lower and upper quartiles of WTP distributions in parentheses.

Attribute	WTP per household per year
Risk 10	$27 (20, 35)
Flow 1	$52 (42, 66)
Ecology good	$84 (62, 105)
Ecology fair	$64 (50, 80)

Table 7  ‘No change’ base and two improvement scenarios.

No change	• 60 people per 1000 become sick from recreational contact each year
	• Ecological quality poor
	• 5 months of low-flow conditions per year
Management fair	• 30 people per 1000 become sick from recreational contact each year
	• Ecological quality fair
	• 3 months of low-flow conditions per year
Management good	• 10 people per 1000 get sick from recreational contact each year
	• Ecological quality good
	• 1 month of low-flow conditions per year

Table 8  Estimates of average compensating surplus (NZ$ 2008). Lower and upper quartiles of CS distribution in parentheses.

Scenario	Annual household	5-year Canterbury	Non-response adjusted
Management fair	$154 (125, 187)	$133 872 980	$80 969 948
Management good	$213 (169, 260)	$185 026 964	$111 946 872