The economic value of research in managing invasive hydrilla in Florida public lakes

Figures & data

Figure 1. Kissimmee Chain of Lakes site map.

Table 1. Actual and counterfactual scenario comparison.

Analysis component	Actual scenario	Counterfactual scenario
Hydrilla control type	Research-informed modern large-scale endothall treatment protocol	Small-scale spot treatments to maintain boat access
Hydrilla growth model	None needed: maintenance control achieved	Model hydrilla regrowth from large standing stock
Angler impacts	None	Start in year 2 after large-scale treatment ceases, based on achieving threshold of cover in hydrilla growth model
Nonangler impacts	None	Start in year 1 after large-scale treatment ceases, because maintenance control ceases
Treatment cost data source	FWC	FWC for aggregate data, SFWMD for cost breakdown data
Research costs	Includes state and federal agency expenditures on control strategies, treatment monitoring, and outreach	None

Table 2. Estimated lake recreational user losses per year due to hydrilla (2017 dollars).

	Kissimmee	Tohopekaliga	Hatchineha	Cypress	Total
Angler losses^a	4,257,726	2,754,518	1,122,941	898,383	9,033,568
Nonangler losses^b	416,431	174,992	122,458	42,734	756,614
Total	4,674,157	2,929,510	1,245,399	941,117	9,790,183

^a Imposed in any year that hydrilla cover is over 80%.

^b Imposed in any year of spot treatments rather than large-scale treatments.

Table 3. Sensitivity analysis of the value of research, discounted to present value at 3% (2017 dollars).

Year after large-scale treatment ceases in which 80% hydrilla cover occurs	Yearly spot treatment area 1%	Yearly spot treatment area 4%	Yearly spot treatment area 8%	Yearly spot treatment area 12%
Year 1	19,456,586	27,111,794	37,318,738	47,525,682
Year 2	11,891,115	19,546,323	29,753,266	39,960,210
Year 3	4,545,997	12,201,205	22,408,149	32,615,092
Year 4	(2,585,185)	5,070,023	15,276,966	25,483,910
Year 5	(9,508,663)	(1,853,455)	8,353,488	18,560,432
Beyond year 5	(16,230,487)	(8,575,279)	1,631,665	11,838,609

Bolded value is the default case. Parentheses indicate negative values.

Figure 2. Yearly ecosystem service losses avoided in the counterfactual, treatment costs in each scenario, and research costs in the actual scenario. Research costs occur over 11 yr whereas other costs are over the 5 yr scenario analysis period.