COMPUTER SIMULATION OF RECREATIONAL BOATING ACTIVITIES1

ABSTRACT This paper is concerned with the portion of harbor improvement planning which identifies the refuge and transient service needs at points along Lake Michigan. The travel behavior model developed to predict this use is sensitive to five criteria: boater characteristics which influence travel behavior; entry rates into the Lake from each access site; site characteristics; weather conditions; and planning parameters. The information provided by this computer model includes: the number of boaters demanding a given access point at a given time; the length of stay at that point; the probability of travel to specific access sites in given amounts of time; and those facilities used during a specified time period. The simulation modelling boat movement consists of two parts; a traffic generation routine and an activity simulation. The former schedules the entry of boats into the Lake from each site and the latter establishes the probabilistic movement of boats on the Lake. This simulation of interport movements and port activities enables the planner to investigate some impacts of alternative small boat harbor development plans.     

A PRELIMINARY STUDY FOR EVALUATING THE CAPACITY OF WATERS FOR RECREATIONAL BOATING1

ABSTRACT The tremendous growth of participation in recreational boating has focused attention on the ability of surface waters to support different types of water-based recreation under intensive use. An important factor in determining the capacity of recreational waters for boating is the satisfaction boaters derive from an area and its use. The recreational experiences of two groups of users as they were affected by levels of use were examined on three intensively used lakes in southeastern Michigan during the summer of 1969. The reactions toward levels of use were obtained from personal interviews with users at the access sites following participation and by self-administered questionnaires distributed to shoreline property owner users. The level of use was recorded by aerial photography at hour intervals. The dispersion of boats and area consumed by boats on the water surface areas over time were quantified and investigated individually and in combination for possible relationships describing the level of use. The satisfaction of users was defined in terms of an index calculated by dividing the number of unfavorable boater responses by the total number of responses for a given time and place. Definite mathematical relationships between levels of use and user satisfaction were established. Based on these relationships, a range of levels of satisfaction for various numbers and groupings of boaters was used to develop boating carrying capacity limits.     

PUBLIC ATTITUDES IN MASSACHUSETTS TOWARD THE RECREATIONAL USE OF DOMESTIC WATER SUPPLY RESERVOIRS1

ABSTRACT: There is considerable controversy inthe Northeast surrounding the extent to whcih public drinking water reservoirs should be used for recreational purposes. This paper reports the results of two integrated studies of (1) recreation users of Quabbin Reservation, the largest inland water source in New England and (2) the general public of Massachusetts. Data were obtained by conducting on-site interviews of Quabbin users and through state-wide telephone interviews of the general public; both studies focused on assessing attitudes toward the recreational use of drinking water reservoirs in Massachusetts. Unlike the findings of a 1969 study conducted by Baumann, results showed that the majority of Massachusetts residents do not favor recreation-prohibiting laws for most activities. Most favored at least moderate use of reservoirs for recreational purposes. In addition, over all views were not as restrictive as present legislation would suggest. Finally, these findings suggest that current recreation-prohibiting laws should be reassessed in light of pugblic opinion which favors the use of these valuable resources.     

EFFECTS OF A RECREATIONAL IMPOUNDMENT ON NEARBY NATURAL LAKES: A CASE STUDY1

ABSTRACT: Completion of a 1270 acre recreational impoundment (Legend Lake) in the glacial sands of Menominee County, Wisconsin, produced geochemical and hydrologic alterations in some nearby natural lakes. The impoundment was produced by the construction of three dams, one of which proved to be temporary, connecting 9 natural lakes and ponds of 383 acres with 951 acres of flooded lands. Water levels were raised 3–15 feet within the impounded area. Much of the flooded area was peat rich wetland associated with the prior drainage. Water depths are less than 15 feet in 70% of the impoundment. Three seepage lakes, located less than 1/2 mile from the impoundment, experienced shoreline flooding, shoreline and soil erosion, some tree kills, and increased turbidity. These lakes also experienced concentration increases in several chemical constituents which indicate an influx of impoundment water through a regional alternation in the groundwater flow paths. The three lakes were connected by canals, and a 2.3 cfs gravity drain with an auxiliary pumping station was built to return excess water to the outflow of the impoundment. Future projects of this type would benefit from a more extensive hydrologic and geochemical analysis prior to initiation. Had environmental assessments been required at the time of this development, as they now are in Wisconsin for similar projects, some of the problems encountered might have been alleviated.     

PHYTOPLANKTON IN THE FOX CHAIN OF LAKES1

ABSTRACT: As part of a comprehensive water quality investigation on the Fox Chain of Lakes during May to October 1975, water samples from the Chain and Cedar Lake (reference) at 25 locations were collected weekly or bi-weekly to determine the species and densities of algae. The results have been evaluated for algal composition, density, and succession for each location. Sixty-four algal species were recovered from 414 samples. The number of species per sampling location varied from 10 at Channel Lake and Lake Marie to 26 on Fox Lake (main) and Grass Lake. Blue green algae were predominant and occurred at 25 of the 25 sampling stations. They consisted mainly of Aphanizomenon flos-aquae. The only flagellate of importance was Ceratium hirundinella, and significant concentrations of this organism were limited to Channel Lake and Lake Catherine. The only green alga bloom was created by Ulothrix variabilis on the waters of Pistakee Lake. Diatoms were quite significant on the shallower water bodies. Algal densities ranged from about 25 to 14,000 cts/ml. The highest count occurred on Mineola Bay. Other high counts (>10,000 cts/ml) observed were waters taken from Channel Lake, Grass Lake, and Fox Lake (main). In Grass Lake, 60 percent of the collections had algal densities in excess of 2,000 cts/ml. Most of these were the diatom Cyclotella meneghiniana.     

UNCERTAINTIES IN ESTIMATING THE WATER BALANCE OF LAKES1

ABSTRACT: Evaluation of hydrologic methodology used in a number of water balance studies of lakes in the United States shows that most of these studies calculate one or more terms of the budget as the residual. A literature review was made of studies in which the primary purpose was error analysis of hydrologic measurement and interpretation. Estimates of precipitation can have a wide range of error, depending on the gage placement, gage spacing, and areal averaging technique. Errors in measurement of individual storms can be as high as 75 percent. Errors in short term averages are commonly in the 15-30 percent range, but decrease to about 5 percent or less for annual estimates. Errors in estimates of evaporation can also vary widely depending on instrumentation and methodology. The energy budget is the most accurate method of calculating evaporation; errors are in the 10–15 percent range. If pans are used that are located a distance from the lake of interest, errors can be considerable. Annual pan-to-lake coefficients should not be used for monthly estimates of evaporation because they differ from the commonly used coefficient of 0.7 by more than 100 percent. Errors in estimates of stream discharge are often considered to be within 5 percent. If the measuring section, type of flow profile, and other considerations, such as stage discharge relationship, are less than ideal errors in estimates of stream discharge can be considerably greater than 5 percent. Errors in estimating overland (nonchannelized) flow have not been evaluated, and in most lake studies this component is not mentioned. Comparison of several lake water balances in which the risdual consists solely of errors in measurement, shows that such a residual, if interpreted as ground water, can differ from an independent estimate of ground water by more than 100 percent.     

OPTIMAL WATER ALLOCATION IN THE LAKES BASIN OF NICARAGUA1

ABSTRACT: The water resources of Nicaragua are largely undeveloped and distributed unequally throughout the nation. In addition, there is a significant geographical imbalance between the abundant water supply in the Atlantic Basin and the less abundant supply in the Pacific Basin which accounts for most of the water demand. The Lakes Basin, comprising Lakes Managua and Nicaragua, could be manipulated to solve the imbalance. Specifically, this paper presents a scheme to transfer water from Lake Nicaragua to Lake Managua and, subsequently, direct water from each lake for irrigation and hydroelectric generation. The scheme has been designed to maximize economic benefits and requires environmental impact analysis.     

PREDICTIVE MODELS FOR THE BIOMASS OF BLUE-GREEN ALGAE IN LAKES1

In lakes which experience water quality problems due to the nuisance growth of blue-green algae, summer concentrations of chlorophyll a may not always be a meaningful measure of water quality for making management decisions. Models for the prediction of summer mean blue-green algal biomass were thus developed from data collected from five systems located in North America and Sweden. It is suggested that the model of choice is log BG =?0.142 + 0.596 log TP – 0.963 log Z, where BG is the biomass of blue-green algae (g m^?3), TP is the concentration of total phosphorus (mg m^?3), and Z is the mean depth of the lake (m). When coupled to current loading models, this model can potentially be used to assess the impacts of phosphorus loading reductions on threshold odor in water supplies.     

PREDICTION OF CHLOROPHYLL A CONCENTRATIONS IN FLORIDA LAKES: THE IMPORTANCE OF PHOSPHORUS AND NITROGEN1

ABSTRACT: Models for the prediction of chlorophyll a concentrations were developed and tested using data on 223 Florida lakes. A statistical analysis showed that the best model was log (Chl a) =?2.49 + 0.269 log (TP) + 1.06 log (TN) or log (Chl a) =?2.49 + 1.06 log (TN/TP) + 1.33 log (TP) where Chl a is the chlorophyll a concentration (mg m^-3), TP is the total phosphorus concentration (mg m^-3) and TN is the total nitrogen concentration (mg m^-3). The model yields unbiased estimates of chlorophyll a concentrations over a wide range of lake types and has a 95 percent confidence interval of 29–319 percent of the calculated chlorophyll a concentrations. Other models, especially the published Dillon-Rigler and Jones-Bachmann phosphorus-chlorophyll models, are less precise when applied to Florida lakes. The data support the hypothesis that nitrogen is an important limiting nutrient in hypereutrophic lakes.     

EFFECTS OF SEDIMENTATION ON THE ALGAL FLORA OF A SMALL RECREATIONAL IMPOUNDMENT1

ABSTRACT: Investigations were initiated to evaluate the effects of sedimentation on the algal composition, primary productivity rates and chemical nutrient concentrations of a 17 acre recreational impoundment in central Virginia. Comparisons during the winter seasons of 1972–1973 indicated that as a result of sedimentation, from lake front home construction, the total numbers of algal genera in the lake decreased from 24 to 16, productivity as measured by ¹⁴CO₂ and total extractable chlorophyll decreased two fold, and several important nutrients, i.e. NH4⁺-N, SiO₂ and PO₄-P increased significantly.     

REGIONAL CHEMISTRY OF LAKES IN MASSACHUSETTS 1

ABSTRACT: We surveyed over 2000 lakes in the State of Massachusetts (1983–1984) to examine the spatial variations in their acid-base chemistry. Our survey differed from previous surveys by including small lakes and nonpristine urban lakes. For samples collected in October 1983 and 1984, the median acid neutralizing capacity (ANC) was 184 μeq L^?1 and 5.9 percent were acidic (ANC≤O). Small lakes (<4 ha) were more likely to be acidic than large lakes. Generally, sulfate was the dominant acidifying agent, although organic anions were dominant in some of the lakes in the Cape Cod Region. The ionic composition of the lakes showed strong regional patterns which appear to be related to geology and human population density. An analysis of variance of ANC shows the six regional categories in the state explain 51 percent of the variance, while a combined general linear model of lake drainage type, color, elevation, size, silica, and hydrogen ion deposition could explain only 4.9 percent of the variation in ANC. Calcium rich, high ionic strength lakes were present in the marble bedrock in the west, and relatively dilute lakes dominated by sodium and chloride were found near the coast. Chloride concentrations were also related to population density, suggesting road salt as a likely contributing source.     

A SEQUENTIAL DECISION APPROACH IN RECREATIONAL ANALYSIS1

ABSTRACT Benefits from recreation facilities are often estimated by multiplying the estimated number of user-days by an administratively determined dollar value per user-day. Such a method requires accurate estimates of total visitation to a proposed facility. Bayesian decision analysis provides a convenient statistical framework in which estimates of recreation visitation estimated using different methods can be combined to provide a more accurate estimate than that obtained from a single source. A Bayesian framework also provides the means of determining the optimal, with respect to a preselected cost function, number of interviews (including zero) that should be conducted in the primary market area. The procedure is demonstrated for a hypothetical recreation site in southern Indiana.     

MODELING OF THE GREAT LAKES WATER SYSTEM1

There have been two predominate approaches to the modeling of the Great Lakes water system: physical models and mathematical models. The physical models have been of individual lakes whereas the mathematical models have varied from models of individual processes such as evaporation occurring in one portion of one lake to models which include all water quantity components for all five Great Lakes. The assumptions and limitations of the two approaches are presented along with the kinds of results to be expected from each type of modeling. Examples of previous modeling efforts are given to illustrate these assumptions, limitations, and results. Other areas requiring further research are outlined.     

A SYSTEMS STUDY OF FUTURE GROUNDWATER DEVELOPMENT COSTS IN THE CHICAGO REGION1

The cost of developing groundwater resources in northeastern Illinois from 198cL2020 is estimated for the purpose of providing a basis for comparing alternative sources. Demands for each township in the study area are estimated at 10-year increments and are satisfied, where the supply is sufficient, in such a way as to minimize the cost subject to constraints on supply. Sources of water are two shallow aquifers with known potential yields and a series of deep aquifers treated as a single unit and modeled on a digital computer. For each township the costs of wells, pumps, power and rehabilitation is estimated for each aquifer on a per million gallons of water per day basis. In addition the cost of groundwater treatment necessary to raise the quality to that of treated Lake Michigan water is considered. Raw water costs are found to vary from 2 to 14 cents per 1000 gallons depending upon the depth to the deep aquifer water. Treated water costs vary from 22 to 53 cents per 1000 gallons, the lower costs applying to the largest users because of the economy of scale. It is found that with proper distribution of pumpage there is sufficient water in storage in the deep aquifers to meet groundwater demands through 2020.     

A NOTE ON THE EVALUATION OF ACTIVITY DEPENDENT RECREATIONAL DAMAGE COST FUNCTIONS1

ABSTRACT: Recreation benefits or costs are an important aspect in the planning for and evaluation of water resources project strategies. How to include in a quantitative fashion the effects of water quality for planning and analysis is yet unresolved. We describe a quantitative formulation for a recreation function in which the water quality is the argument, and suggest how the coefficients may be evaluated.     

SUPPLEMENTAL IRRIGATION OF HORTICULTURAL CROPS IN THE HUMID REGION1

ABSTRACT: A computer model was developed in order to establish a yield predictive relationship and to estimate the water requirements for supplemental irrigation of horticultural crops in the humid region. Alternative distribution systems were developed and designed using the results from the computer model and Wood's (1980) pipe network algorithm. The capital, operational, and maintenance costs of the distribution and recommended on-farm irrigation systems were determined and used to evaluate the economic feasibility of the alternative designs. Results show that the concentration of irrigated area along the distribution system, the length of the distribution system, and cropping system all have an important effect on the economic feasibility of supplemental irrigation in Wayne County, Kentucky.     

ESTIMATION OF POTENTIAL REDUCTIONS IN RECREATIONAL BENEFITS DUE TO SEDIMENTATION1

ABSTRACT: A travel cost model is developed to estimate the potential reductions in recreational benefits from sedimentation in Reelfoot Lake in northwestern Tennessee. In addition to the consumer surplus estimates generated by the model, three other aspects of the study were significant. First, the study applied a relatively untested methodology for deriving the opportunity cost of travel time. The study resulted in a value that is less than one-half of the Water Resource Council's “one-third of the wage rate” rule-of-thumb. Second, water quality perceptions were unsuccessfully incorporated into the model as a demand shifter. This raised questions as to the appropriate manner in which perceptions could be included in a travel cost model. Finally, a simple methodology was outlined by which estimates of the recreational value of Reelfoot Lake could be used to suggest how much cost could be justified for soil erosion control on agricultural land surrounding the lake.     

ESTIMATED BACKGROUND CONCENTRATIONS OF SULFATE IN DILUTE LAKES1

ABSTRACT: Lake water sulfate values were examined for two areas in western Norway and the western United States presently receiving low levels of sulfate in atmospheric deposition. Data from these areas were used to estimate background concentrations of sulfate in lakes found in areas currently receiving acidic deposition. The two areas contain dilute lakes with concentrations of sea-salt corrected Ca+ Mg less than 50 μeq/l or conductivity < 10μS cm^-1and receive precipitation with volume-weighted mean pH > 4.8. Based on observations from these areas, we conclude that background sulfate concentrations were probably no more than 10 to 15 μeq L^-1for areas of Norway and the U.S. containing lakes with low concentrations of base cations. For southern Norway and the northeastern U.S., present lakewater sulfate concentrations represent an increase of 7 to 10 fold above these estimated background values.     

AN ECOLOGICAL AND RECREATIONAL USE SURVEY OF THE LUXAPALILA RIVER1

An ecological and recreational use survey was made of the Luxapalila River in Mississippi. This study was made before channelization work was started by the Army Corps of Engineers. A follow-up study is planned after channelization work is completed. Four stations were located along a 10.5 mile stretch of river where certain chemical and biological measurements were taken during the four seasons of the year. The results of this study revealed that the river is an unpolluted, biologically productive waterway relatively high in chemical constituents. Eleven families and 37 different species of fish were collected. Biomass measurements of standing crops of invertebrates ranged from a low of 0.11 grams oven dry weight per square meter to a high of 18.89 grams per square meter, with larger biomass collected from eddy areas than from riffle areas. A survey of recreational use of the river indicated relatively light use was made of the river. Fishing was the major use followed by swimming.