Usefulness of natural regions for lake management: Analysis of variation among lakes in northwestern Wisconsin,USA

A map of summer total phosphorus in lakes was compiled recently for a three-state area of the upper Midwest for purposes of identifying regional patterns of total phosphorus in lakes and attainable lake trophic state. Spatial patterns in total phosphorus from approximately 3000 lakes were studied in conjunction with maps of geographic characteristics that tend to affect phosphorus balance in lakes to identify regions of similarity in phosphorus concentrations in lakes or similarity in the mosaic of values as compared to adjacent areas. While degrees of relative homogeneity are apparent at many scales, the map was designed at a scale that would yield regions with sufficient homogeneity to be useful for lake management throughout the area. In this study, data from 210 lakes in a 1560-mi² area in northwestern Wisconsin, sampled by the Wisconsin Department of Natural Resources in the spring of 1988 (subsequent to the compilation of the phosphorus map), were examined to: (1) substantiate the existence of the regions depicted on the map in northwest Wisconsin, (2) determine the nature and relative precision of the regional boundaries, (3) determine the relative importance of natural and anthropogenic watershed characteristics, lake types, lake area, and lake depth in explaining within-region differences in lake phosphorus, and (4) demonstrate how the regions might be used by local lake managers.     

云南高原湖泊流域土地利用与水质变化异质性分析

以云南省九大高原湖泊为例,通过面板数据方式分析对高原湖泊流域土地利用类型变化,通过库兹涅兹曲线相关内容对利用强度的分析以及与水质的动态变化情况,得到耕地、园地、湿地面积与湖泊含磷量存在一定负相关.林地、牧草地、建设用地面积与湖泊含磷量存在一定正相关.牧草地、耕地、园地、湿地面积与湖泊含氮量存在一定负相关,建设用地面积与湖泊含氮量存在一定正相关.园地和耕地面积与污染综合指数存在负相关,建设用地面积与污染综合指数存在负相关.分析指出,滇池、泸沽湖处于流域协调区间,阳宗海、抚仙湖、星云湖、程海处于流域冲突区间,洱海、异龙湖处于冲突区间向协调区间转型过程中.     

THE EFFECT OF SALT ON SMALL,ARTIFICIAL LAKES1

ABSTRACT: Northridge Lakes, in Milwaukee, Wisconsin, receive runoff from a 3.8 square kilometer drainage area. Almost 30% of the watershed is covered by shopping centers, apartment buildings, and roadways. Deicing agents used on the paved areas, primarily NaCl with some CaCl₂, dissolved in surface runoff and entered the lakes during the winter season. This highly saline inflow was denser than the receiving lake water and formed a saline-water stratum at the lakes' bottom. The salinity stratification remained stable until the spring thaw when a rapid decay began. After the stratification had disappeared, the lakes continued to act as a storage site for dissolved salts. Chloride concentrations in the lakes remained well above the levels found in natural lakes until the advent of the next salting season. Furthermore, outflow from the lakes also showed abnormally high salt concentrations year-round.     

Housing growth,forests, and public lands in Northern Wisconsin from 1940 to 2000

Rural, forested areas throughout the United States are experiencing strong housing growth with potentially detrimental impacts on the environment. In this paper, we quantify housing growth in Northern Wisconsin over the last sixty years to determine if growth rates were higher near public lands, which may represent an important recreational amenity. We used data from the U.S. Census to produce decadal housing density estimates, “backcasts,” from 1940 to 2000 for northern Wisconsin to examine “rural sprawl” in northern Wisconsin and its relationship to forested areas and public lands. We integrated housing density estimates with the 1992/1993 National Land Cover Dataset to examine the relationship between rural sprawl and land cover, especially forests. Between 1940 and 2000, private land with <2 housing units/km² decreased from 47% to 21% of the total landscape. Most importantly, housing growth was concentrated along the boundaries of public lands. In 14 of the 19 counties that we studied, housing growth rates within 1 km of a public land boundary exceeded growth rates in the remainder of the county, and three of the five counties that did not exhibit this pattern, were the ones with the least amount of public land. Future growth can be expected in areas with abundant natural amenities, highlighting the critical need for additional research and effective natural resource management and regional planning to address these challenges.     

Summer total phosphorus in lakes: A map of Minnesota,Wisconsin, and Michigan,USA

A map of summer total phosphorus in lakes has been compiled for Minnesota, Wisconsin, and Michigan to clarify regional patterns in attainable lake trophic state. Total phosphorus was used as a measure of lake trophic state because: (1) phosphorus plays a central role in controlling the overall fertility of most lakes, (2) total phosphorus values are available for a great number of lakes, and (3) phosphorus is measured in a consistent manner. The maps were compiled using patterns of total phosphorus data and observed associations between these data and geographic characteristics including physiography, land use, geology, and soils. Regions depicted on the map represent areas of similarity in phosphorus concentrations in lakes, or similarity in the mosaic of values, as compared to adjacent areas. Within each region, differences in total phosphorus can be compared to natural and anthropogenic factors to determine the types of lakes representative of each region, the factors associated with differences in quality, and the realistically attainable phosphorus levels for each type of lake.     

Lakes,Wetlands, and Streams as Predictors of Land Use/Cover Distribution

The importance of the surrounding landscape to aquatic ecosystems has been well established. Most research linking aquatic ecosystems to landscapes has focused on the one-way effect of land on water. However, to understand fully the complex interactions between aquatic and terrestrial ecosystems, aquatic ecosystems must be seen not only as receptors of human modification of the landscape, but also as potential drivers of these modifications. We hypothesized that the presence of aquatic ecosystems influences the spatial distribution of human land use/cover of the nearby landscape (≤1 km) and that this influence has changed through time from the 1930s to the 1990s. To test this hypothesis, we compared the distribution of residential, agricultural, and forested land use/cover around aquatic ecosystems (lakes, wetlands, and streams) to the overall regional land use/cover proportion in an area in southeast Michigan, USA; we also compared the distribution of land use/cover around county roads/highway and towns (known determinants of many land use/cover patterns) to the regional proportion. We found that lakes, wetlands, and streams were strongly associated with the distribution of land use/cover, that each ecosystem type showed different patterns, and that the magnitude of the association was at least as strong as the association with human features. We also found that the area closest to aquatic ecosystems (<500 m) was more strongly associated with land use/cover distribution than areas further away. Finally, we found that the strength of the association between aquatic ecosystems and land use/cover increased from 1938 to 1995, although the overall patterns were similar through time. Our results show that a more complete understanding is needed of the role of aquatic ecosystems on the distribution of land use/cover.     

AN ECONOMIC AND ENVIRONMENTAL EVALUATION OF ALTERNATIVE LAND DEVELOPMENT AROUND LAKES1

ABSTRACT: The objective of the study was to evaluate alternative land developments around New Hampshire lakes. Alternative development patterns, evaluated by their impacts on the lake area environment and area economy, included residential patterns, commercial patterns, and combinations of these two types. Phosphorus loading of the lake water was used as a proxy variable for changes in the lake water quality. Commercial developments yielded the highest revenues to the town and the local area. It also attracted the most lake users to the area as well as contributing the largest phosphorus loading in the lake waters. Residential developments, although contributing high revenues to the businessmen in the area, yielded less net income to the town. Phosphorus loading levels from residential developments were much lower than lake phosphorus loading by commercial developments.     

Boater Perceptions of Environmental Issues Affecting Lakes in Northern Wisconsin

Understanding public perceptions of the importance of environmental issues is crucial for gauging support for management activities. I present a novel methodological approach to assess the importance boaters placed on 16 water issues in a lake‐rich region of northern Wisconsin. A latent class maximum difference conjoint model was used to examine the relationships between environmental concern and engagement with lake resources. Boaters were grouped to maximize observed heterogeneity in prioritizing issues of concern. Socio‐demographic characteristics, recreation specialization, place attachment, and attitudes concerning aquatic stewardship and invasive species management were then used to predict class membership. This modeling approach identified five groups whose perceptions of issues pertaining to lakes are influenced by their interactions with the lake environment. While anglers were most concerned about fishing quality, sightseers identified lakeshore development and loss of natural habitat. Groups also differed in their socio‐demographic and attitudinal characteristics. The priorities of each group were substantially different from those of the overall sample. Accounting for differences in stakeholders' environmental concerns may improve public involvement in water management initiatives by allowing managers to identify common concerns and prioritize important issues among multiple groups.     

EFFECTS OF PRECIPITATION AND LAND USE ON STORM RUNOFF1

ABSTRACT: Storm-runoff quantity and quality were studied in three watersheds located near St. Paul in Ramsey County, Minnesota, from April 15 through September 15 of 1984, 1985, and 1986 to qualitatively determine the effects of precipitation and selected land uses on storm runoff. In respect to precipitation effects, differences in stormrunoff quantity between years in an urban watershed that lacks wetlands appear to be related to the average storm size (amount of precipitation) during the study period of each year. In contrast, the differences in storm-runoff quantity from watersheds that contain wetlands appear to be related to total precipitation during study period of each year. In respect to land use, the differences in storm-runoff quantity appear to be related to the amounts of impervious and wetland area. The watershed that contains the largest amount of impervious area and smallest amount of wetland area has the largest amount of storm runoff. Differences in storm-runoff quality appear to be related to the amounts of wetland and lake area. The watershed that contains the largest amounts of wetland and lake area has the smallest storm-runoff loading of suspended solids, phosphorus, and nitrogen. The wetland and lake areas likely retain the loading and, subsequently, lower the amount of storm-runoff loading exported from a watershed.     

Geospatial and Temporal Analysis of a 20‐Year Record of Landsat‐Based Water Clarity in Minnesota's 10,000 Lakes

A large 20‐year database on water clarity for all Minnesota lakes ≥8 ha was analyzed statistically for spatial distributions, temporal trends, and relationships with in‐lake and watershed factors that potentially affect lake clarity. The database includes Landsat‐based water clarity estimates expressed in terms of Secchi depth (SD_Landsat), an integrative measure of water quality, for more than 10,500 lakes for time periods centered around 1985, 1990, 1995, 2000, and 2005. Minnesota lake clarity is lower (more turbid) in the south and southwest and clearer in the north and northeast; this pattern is evident at the levels of individual lakes and ecoregions. Temporal trends in clarity were detected in ~11% of the lakes: 4.6% had improving clarity and 6.2% had decreasing clarity. Ecoregions in southern and western Minnesota, where agriculture is the predominant land use, had higher percentages of lakes with decreasing clarity than the rest of the state, and small and shallow lakes had higher percentages of decreasing clarity trends than large and deep lakes. The mean SD_Landsat statewide remained stable from 1985 to 2005 but decreased in ecoregions dominated by agricultural land use. Deep lakes had higher clarity than shallow lakes statewide and for lakes grouped by land cover. SD_Landsat decreased as the percentage of agriculture and/or urban area increased at county and catchment levels and it increased with increasing forested land.     

Lake area changes in the middle Yangtze region of China over the 20th century

The Jianghan Plain and the Dongting lake area, located in the middle reaches of the Yangtze River are famous for their abundant freshwater lakes. The lakes have undergone changes in size and number over thousands of years due to natural causes and human activities. The 20th century particularly, witnessed dramatic changes in the freshwater resources of this region. This paper traces and analyzes lake evolution in the middle reaches of the Yangtze River over the past century. Lakes greater than 0.1 km(2) in size are mapped using Geographic Information System. Data is acquired and integrated from drainage network maps, relief maps, historical maps and remotely sensed images for different time periods. The results indicate that while there has been little change in the number of lakes over the past century, the lake area has experienced a dramatic decrease of 58.06%. The paper also examines the natural processes and human activities that may have contributed to the decrease in lake area. The results show that the decrease in total lake area appears to coincide with periods of rapid land reclamation in the middle reaches of the Yangtze River. Moreover, uncontrolled land reclamation activities can create an increase in sediment deposition in lakes thereby further reducing the lake size. Reduction of the lake area directly affects flood-control and has a negative ecological impact on the environment and on human life and property.     

REMOTE MONITORING OF SELECTED GROUND‐WATER DOMINATED LAKES IN THE NEBRASKA SAND HILLS1

ABSTRACT: The Landsat‐Muitispectral Scanner (MSS) data were used to measure lake area fluctuations (1972–1989) for 130 ground‐water dominated lakes in the Western Lakes Region of the Nebraska Sand Hills. In general, the pattern shown in lake area hydrographs was similar to that for in‐situ lake elevations. In‐situ lake‐elevation data verify that remote monitoring of surface‐area fluctuations, even at relatively coarse spatial resolution, is not only practical and useful, but also it elucidates the hydrologic characteristics of groundwater‐dominated lakes of the Sand Hills. The apparent differences in behavior between lakes in the northern and southern portions of the study area may be related to both their location in the regional ground water system and the substantial local hydrologic complexity.     

Institutional aspects of lake management

The major barriers to successful lake management are institutional. However, in contrast to the technical and limnological dimensions of lake management, the institutional aspects of managing lakes have received little attention. The institutional factors that are important for successful lake management outcomes are: overlapping areal jurisdiction among governmental units, fragmented functional program responsibilities, ineffective coordination, limited authority, financial constraints, private sector roles, and inadequate public awareness and consensus. The range of typical institutional problems confronting lake management are well illustrated through experiences from the state of Wisconsin, USA. Because lake management programs with institutional shortcomings rarely realize their goals, it is critical to assimilate, evaluate, and apply our experience to date with the institutional arrangements necessary to effectively manage lake resources.     

VARIATION IN ADIRONDACK,NEW YORK,LAKEWATER CHEMISTRY AS FUNCTION OF SURFACE AREA1

ABSTRACT: Data from a recent survey conducted by the Adirondack Lake Survey Corporation were used to evaluate the influence of lake surface area on the acid-base status of lakes in Adirondack State Park, New York. Acid neutralizing capacity (ANC) in the small lakes (< 4 ha) occurred more frequently at extreme values (> 200, < 0 μeq L^?1), whereas larger lakes tended to be intermediate in ANC. Consequently, acidic (ANC ≤ 0) and low-pH lakes were typically small. The small lakes also exhibited lower Ca²⁺ concentration and higher dissolved organic carbon than did larger lakes. Lakes ≥ 4 ha were only half as likely to be acidic as were lakes ≥ 1 ha in area. These data illustrate the dependence of lake chemistry on lake surface area and the importance of the lower lake area limit for a statistical survey of lake water chemistry.     

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.     

Mesoscale survey of western and northwestern Irish lakes – Spatial and aestival patterns in trophic status and phytoplankton community structure

Inland water bodies are considered as integrated parts of the landscape and the monitoring of water quality and aquatic resources need to be addressed on a regional basis for optimal assessment and management. In this study, a simple stratified sampling scheme was applied to a mesoscale survey of western and northwestern Irish lakes, which was carried out to identify, based on the distribution patterns of phytoplankton biomass, potential associations between lake trophic state and land cover attributes. Phytoplankton community analysis was also performed to determine whether taxa associations reflected meteorology-linked aestival succession or specific spatial distributions. The assessment was based on the typology of hydrogeomorphological and land cover attributes of river catchments through ArcGIS analysis. Sampling was carried out in 50 lakes and during a 15-week period in summer 2009. Results showed a general longitudinal gradient in the trophic status of the lakes sampled, with a greater frequency of mesotrophic lakes in the eastern part of the study area where land cover is dominated by agricultural surfaces. Significant relationships (p < 0.010) were found between chlorophyll-a concentration and the proportion of river catchment surface covered by agriculture land and wetlands, findings which might be considered further as proxies for developing an eutrophication risk index. Multivariate analysis of phytoplankton community data clustered the sampled lakes into three assemblages, with ordination along axis 1 being significantly correlated to time and temperature (p < 0.006). There was greater frequency of occurrence of diatoms in lakes from cluster III (Kruskal–Wallis, p < 0.05, H = 6.34, df = 2, n = 49), concomitant to lower chlorophyll-a concentrations, lake surface temperatures and Secchi depths, reflecting meteorological conditions dominated by precipitations. Those results support the potential of mesoscale surveys to assess water quality variables and detect environmental patterns at regional scales.     

THE EFFECTS OF AGE AND WATER FLUCTUATIONS ON FISH POPULATIONS1

ABSTRACT Two lakes having similar soil types were studied to determine the effects of age and water fluctuations on plankton, benthos and fish populations. Bluff Lake is an older man-made lake which is drawn down in the mid-summer. Oktibbeha County Lake is a young lake and the water levels are maintained. Chemistry data from the two lakes indicate that their chemical properties are very similar. Neither lake would be considered very fertile. Net plankton populations in Bluff Lake and Oktibbeha County Lake were comparable when analyzed on a number of organisms per liter basis. Fluctuations of water levels did not seem to have an effect on the net plankton populations. The benthic population in Bluff Lake is slightly higher than that found in Oktibbeha County Lake. This is true for both numbers and weight per square meter. The species composition of benthic organisms in the two lakes were similar. Based on one-acre samples from each lake, Bluff Lake has a more balanced fish population than does Oktibbeha County Lake. Neither, however, seems to support populations of game fish in which a high percentage of these are in the available or harvestable range. Both lakes contain high populations of gizzard shad.     

INDEX OF LAKE BASIN LAND USE FOR LAND USE PLANNING PURPOSES1

ABSTRACT: In order to plan for land use in a lake basin to maintain or improve lake water quality, municipal planners need a method of evaluating lakeshore and watershed land use that is technically sound, objective, reasonably quick, and cheap enough to be incorporated into their time and dollar budgets. Such a system is presented. It consists of measuring and rating four lakeshore land use characteristics (type of sewage disposal system, lot size, road proximity, and intensity of public use areas), and three upland watershed land use characteristics (intensity of development, forest cover, and agriculture and open space). These seven characteristics are measured, rated, and then combined to provide a two-digit index number. This number, when compared with the indexes of other lakes in the region and interpreted with assistance from officials of the State Health and Water Resources Department, indicates on a relative basis the degree to which various land uses are contributing to accelerated, cultural eutrophication. Interpretation of the index suggests land use controls necessary to improve lake water. It supplements, and should be used with, an index of lake vulnerability to accelerated eutrophication and a comparative measure of present water quality.     

A Hydrological Model for Predicting the Effects of Dams on the Shoreline Vegetation of Lakes and Reservoirs

/ The species richness of shoreline vegetation of unregulated lakes in Nova Scotia, Canada, is known to increase as a function of catchment area, a topographic variable governing water level fluctuations. Predictions based on catchment area however, fail to account for richness patterns at the margins of lakes enlarged by dams. Here, we compare the vegetation and hydrological regimes of regulated and unregulated systems. Hydrological regimes of regulated systems deviated from natural systems of similar catchment area by being either hypovariable or hypervariable for both within-year and among-year fluctuations in water level. Plant communities of dammed systems were less diverse, contained more exotic species, and were, with one exception, devoid of rare shoreline herbs. Data from "recovering," or previously dammed systems indicated that shoreline communities can be restored upon return of the appropriate hydrological regime. Using observed within-year and among-year water level fluctuation data, we propose a general model for the maintenance or restoration of diverse herbaceous wetlands on shorelines of temperate lakes or reservoirs. Managers can manipulate the within-year water level variation within prescribed limits (1-2 m), while ensuring that among-year variation (SD of summer levels) is less than 25% of within-year variation. This preliminary model is based on data from low-fertility, temperate lakes in river systems. To calibrate the model, plant community data from other regions are needed, as are long-term water-level data for unregulated lakes, data which are essential but largely lacking in many areas.KEY WORDS: Catchment area; Regulated lakes; Shoreline restoration; Rare plants; Exotic plants; Diversity     

Effects of Water Withdrawal From Ice‐Covered Lakes on Oxygen,Temperature, and Fish1

Abstract: In northern regions, large volumes of water are needed for activities such as winter road construction. Such withdrawals, particularly from small lakes, can reduce oxygen concentrations and water levels, potentially affecting aquatic organisms. Withdrawal limits have been developed by regulatory agencies, but are largely theoretical. Water withdrawal thresholds were tested in two small lakes by removing 10% and 20% of their respective under‐ice volumes and comparing oxygen parameters, temperature, over‐wintering habitat, and northern pike (Esox lucius) abundance to reference conditions. Because of a milder winter, oxygen parameters were elevated in reference lakes in the period following withdrawal compared to the prewithdrawal period. The 10% withdrawal resulted in a ?0.2 m shift in the oxygen concentration profile at 4 mg/l in that lake, but had no effect on total volume‐weighted oxygen, or volume of over‐wintering habitat. In contrast, the 20% withdrawal caused 0.7 m reduction in the oxygen concentration profile at 4 mg/l compared to the previous year, a 26% decline in the volume‐weighted oxygen concentration, and a 23% reduction in the volume of over‐wintering habitat compared to prewithdrawal conditions. Water temperatures were slightly (≤ 10%) colder in the upper strata in the year following the withdrawal in both withdrawal and reference lakes. Northern pike abundance was not impacted by water withdrawals in either of the lakes. The results of this study show that the effects of water withdrawal on the parameters investigated reflected the characteristics of the lakes, and would therefore be expected to vary from lake to lake. Policy development to mitigate impacts must therefore reflect the site‐specific nature of water withdrawal.