Within the park, shadow prices for tenting and day use of park faciUties 

 were less than the net prices employed in the analysis. This indicates that more 

 facilities should have a beneficial effect but that benefits from additional units 

 are declining. Park land and shoreline were valued at the same shadow price as 

 private resource holdings. 



Private tenting with access to water was dominated by other shore front 

 activities, received a positive shadow price, and did not expand beyond the 

 minimum now available. In contrast, private tenting without access to water 

 expanded to its constraint maximum (double present facilities), with a shadow 

 price equal to its model price. 



4.7 Boating and Pollution from Outboard Engine Exhaust 



The major determinant of the imputed value of lake surfaces was boating. 

 Guidelines for boating use have been provided by the Michigan Outdoor Rec- 

 reation Plan and were employed in determining boat usage.' Boats were normal- 

 ized at 16-foot length with a 40-horsepower outboard engine. Five acres of 

 surface water were assumed, based on intensive usage, and the boat assumed to 

 be under full power one-half of the time. 



Residents of vacation homes and tenters were assumed to use their boats 

 two hours per day and the boats to be under full power half of that time, or 

 one hour per day. For day boat users launching at a public or private ramp, the 

 use time was doubled. 



In the preceding analysis, 516 boat-months (1 hour per day for 30 days) 

 were used on the 3,020 acres of lakes. This amounted to one boat per 5.85 

 acres. 



The effect of outboard engine exhaust on lake-water quality became a major 

 concern in the analysis. There appears to be a need for much work to be done 

 on this type of pollution under field conditions. Most studies including the 

 most recent begin extending experimental work to field conditions with some 

 assumption about length of operating time and experiment results.^ The polluting 

 effect of one hour of boating per day, on a monthly average, is unknown. 



Parametric programming was employed to investigate effects of pollution on 

 optimum boat use. It was assumed that a water-purifying substance, such as 

 activated carbon, could be employed per hour of boat use at some cost. This 

 boat pollution treatment cost was increased from to $60. The critical value 

 determined was $12.30. At tliis point the 516 boats declined to 215, the min- 

 imum number of boats permitted in the constraints. The number of shore va- 

 cation cottages with boats dechned by an equivalent amount. The shadow price 

 on surface water declined steadily as pollution abatement cost increased and 

 reached dollars at the critical cost of $12.30 per boat. The large shift in boat 

 numbers at the critical cost was-due to the nature of the linear programming 

 model. The large shift is not unreasonable for field conditions because lakes 

 are often zoned to allov/ no outboard motors. 



llbid. 

 Environmental Protection Agency. Control of Pollution from Outboard Engine 

 Exhaust: A Reconnaissance Study. Environmental Protection Agency, Research and 

 Monitoring, 15020, ENN, September, 1971. 



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