LAKE LEVEL DRAWDOWN AS A MACROPHYTE CONTROL TECHNIQUE1

ABSTRACT: Lake drawdown as a management or restoration technique for controlling macrophytes in eutrophic lakes is reviewed for effectiveness, longevity, and positive and negative impacts. Drawdown can be effective but is species specific, and some nuisance plants are resistant or stimulated. The responses of 63 nuisance plants are reviewed. Advantages of the technique include low cost, absence of toxic chemicals, enhancement of fisheries, and the opportunity to carry out other lake improvements. Drawbacks include nutrient release, algal blooms, low dissolved oxygen, lake user dissatisfaction during the process, and failure to refill. The technique is recommended for situations where susceptible species are the major nuisance and where prolonged (1–2 months) dewatering of sediments under rigorous conditions of heat or cold is possible.     

MACROPHYTE COMMUNITY DYNAMICS IN A DREDGED WISCONSIN LAKE1

ABSTRACT This paper describes the change in the macrophyte community caused by dredging a small Wisconsin lake. In water depths up to 1.5 m, revegetation was rapid after dredging. The plant community changed from one dominated by large-leafed Potamogeton (pondweed), Megalodonta beckii (water marigold), and Elodea canadensis (waterweed) to one dominated by Chara (stonewort), Najas flexilis (naiad), and Myriophyllum (milfoil). Plant growth ended at the 4 m depth and growth recovered much more slowly in water depths between 1.5 and 4 m. The area between 1.5 m and 2.5 m in particular supported a monotypic milfoil stand after dredging.     

EFFECT OF pH ON PHOSPHORUS RELEASE DURING MACROPHYTE (ELEOCHARIS sp.) DECOMPOSITION1

ABSTRACT: Laboratory microcosms were used to evaluate the effect of pH on release of soluble reactive phosphorus (SRP) during aerobic decomposition of the aquatic macrophyte Eleocharis sp., which is common in oligotrophic Florida lakes. The total amount of SRP released during a 227-day incubation in the dark was independent of pH over the range 3.7 to 5.5, but initial rates of release were faster at the lowest pH. The results indicate that the low total phosphorus concentrations observed in many acidic lakes are not necessarily attributable to reduced rates of decomposition and nutrient mineralization at low pH, as some researchers have suggested.     

EFFECTIVENESS OF TIMBER HARVEST PRACTICES FOR CONTROLLING SEDIMENT RELATED WATER QUALITY IMPACTS1

ABSTRACT: Timber harvest best management practices (BMPs) in Washington State were evaluated to determine their effectiveness at achieving water quality standards pertaining to sediment related effects. A weight‐of‐evidence approach was used to determine BMP effectiveness based on assessment of erosion with sediment delivery to streams, physical disturbance of stream channels, and aquatic habitat conditions during the first two years following harvest. Stream buffers were effective at preventing chronic sediment delivery to streams and physical disturbance of stream channels. Practices for ground‐based harvest and cable yarding in the vicinity of small streams without buffers were ineffective or only partially effective at preventing water quality impacts. The primary operational factors influencing BMP effectiveness were: the proximity of ground disturbing activities to streams; presence or absence of designated stream buffers; the use of special timber falling and yarding practices intended to minimize physical disturbance of stream channels; and timing of harvest to occur during snow cover or frozen ground conditions. Important site factors included the density of small streams at harvest sites and the steepness of inner stream valley slopes. Recommendations are given for practices that provide a high confidence of achieving water quality standards by preventing chronic sediment delivery and avoiding direct stream channel disturbance.     

SEDIMENT RESUSPENSION AND DRAWDOWN IN A WATER SUPPLY RESERVOIR1

ABSTRACT: The magnitudes and patterns of sediment resuspension are assessed in Cannonsville Reservoir, New York, to quantify and characterize this internal source of sediment. The assessment is based on analyses of sediment trap collections from 10 sites over the spring to fall interval of two years. Temporal and spatial patterns in sediment deposition are demonstrated to be driven by resuspension/redeposition processes. Sediment that had been resuspended and redeposited represented 80 to 96 percent, on average, of the depositing solids collected along the main axis of the lake. About 90 percent of the redeposited sediment was inorganic. Increased resuspension caused by drawdown of the reservoir surface and fall turnover resulted in 10 to 50‐fold increases in deposition rates compared to levels observed when the reservoir was full and strongly thermally stratified. Elevated levels of redeposition from resuspension in the reservoir have been driven by both higher water column concentrations of suspended solids and settling velocities. Recurring longitudinal and lateral gradients in resuspension are delineated, establishing that resuspended solids are transported from the riverine to the lacustrine zone and from near‐shore to pelagic areas. Resuspension is demonstrated to cause increases in inanimate particle (tripton) concentrations. Higher tripton levels have been observed in years with greater drawdown. Water quality impacts of the resuspension phenomenon are considered.     

COVERING BOTTOM SEDIMENTS AS A LAKE RESTORATION TECHNIQUE1

ABSTRACT: Sediment covering to control macrophytes and sediment nutrient release is reviewed. It is concluded that fly ash application to control sediment phosphorus release presents more dangers to the lake than benefits and should not be used. Polyethylene sheeting has not had long term effectiveness due to macrophyte regrowth on its surface. PVC-coated fiberglass screen is expensive but nontoxic and appears to give long term macrophyte control. Similar results may be obtained with spun-bonded polypropylene. Sand, clay, and sheeting to retard nutrient release have received insufficient attention.     

EFFECTIVENESS OF ALUM IN A WEEDY,SHALLOW LAKE1

ABSTRACT: An alum treatment in Long Lake (mean depth, 2 m) in 1980 has been effective at controlling internal loading of phosphorus for four years. The fifth summer after treatment, the lake returned to its pro-treatment state. Lake P content decreased from a summer average of 65 μg/L during 1976–1978 to about 30 μg/L during four years following treatment. In 1985, summer P content was 61 μg/L. Algal abundance, species composition, and transparency have responded proportionately with P. Alum effectiveness apparently declined because the floe layer tended to sink and become dispersed at a deeper level in the sediment, as well as become covered with new, P-rich sediment. Iron-reduction may be the principal mechanism for internal P loading, although the lake is unstratified and anoxia is usually not pronounced.     

SAMPLING CHARACTERISTICS OF MACROPHYTE BIOMASS1

ABSTRACT: This paper discusses the virtues of a stratified random system for sampling aquatic plant biomass. It also discusses factors which might be wed to stratify samples and it presents a case study of Lilly Lake, wisconsin, where a stratified random system reduced sampling efforts by about 37 percent.     

EFFECTS OF WATER DRAWDOWN ON THE FAUNA IN SMALL COLD WATER RESERVOIRS1

ABSTRACT: Two small cold water reservoirs with stable water levels were compared with two reservoirs scheduled for complete drawdown to determine the effects of drawdown on invertebrate abundance and fish abundance and density. An extensive literature review supplemented the results with other applicable information. No conclusive evidence of effects of drawdown on invertebrates or fish was found. Characteristics of a reservoir and its drainage basin which obscure or lessen drawdown effects are discussed. Analysis and observation of drawdown procedures showed that duration and scheduling of draw-down periods are important in determining whether drawdown will be harmful to fauna in a given reservoir.     

AN IN SITU COMPARISON OF THE EFFECTIVENESS OF FOUR ALGICIDES1

ABSTRACT: Four algicides (copper citrate, copper ethanolamine, simazine, and diuron) were tested for effectiveness using in situ bio-assays. Bioassays were conducted in clear polyethylene bags and algicide effectiveness measured by chlorophyll a, productivity, and algal counts. The body of water where this testing took place had a high pH (9.2), and high levels of total dissolved solids (610 mg/l) and nutrients. The order of effectiveness found in this study was simazine > diuron > copper ethanolamine > copper citrate.     

EFFECTIVENESS OF POLYACRYLAMIDE (PAM) IN IMPROVING RUNOFF WATER QUALITY FROM CONSTRUCTION SITES1

ABSTRACT: Erosion from construction sites significantly affects water quality in receiving streams. A rainfall simulator was used to evaluate the effectiveness of different methods for controlling erosion from construction sites. Erosion control methods investigated included dry and liquid applications of polyacrylamide (PAM), hydroseed, and straw mulch. Fertilizer was also applied to each plot to examine the effectiveness of the methods in reducing nutrient losses in runoff. Runoff samples were analyzed for total suspended solids (TSS), nitrate, total Kjeldahl nitrogen (TKN), ammonium, total phosphorus (TP), and orthophosphate. Among all treatments investigated, straw mulch was the most effective treatment for controlling TSS and nutrient losses during short term and long term simulations. The low liquid PAM (half the recommended PAM) treatment resulted in the highest reduction in runoff, TSS bound nitrogen, and total nitrogen (TN) concentrations and loadings. The study results indicate that a high application rate (twice the recommended rate) of PAM could actually increase runoff and TSS losses. At a low application rate, both liquid and dry PAM were effective in reducing TSS and nutrient losses in runoff. However, application of the liquid form of PAM to construction sites is more practical and perhaps more economical than applying the PAM in the dry form.     

CONTROLLING NONPOINT EXTERNALITIES WITH INPUT RESTRICTIONS IN AN IRRIGATED RIVER BASIN1

ABSTRACT: Irrigated agriculture is a major nonpoint source of surface water quality degradation. Nonpoint source discharges can be controlled by either output taxes or restrictions, or input taxes or restrictions. The economic theory of externality control with taxes or restrictions on input use is developed. The effectiveness of alternative input control policies in improving surface water quality is demonstrated with a mathematical model of the agriculture and water quality in Washington State's Yakima River Basin. Water quality parameters considered were river nitrogen concentration, water temperature, and cropland soil losses. Producer and social abatement costs were the most important measures of policy effectiveness.     

EFFECTIVENESS OF BIOPHYSICAL CRITERIA IN THE HIERARCHICAL CLASSIFICATION OF DRMNAGE BASINS1

ABSTRACT: A subwatershed base map of 84 hydrologic subregions within the Columbia River Basin (approximately 58,361,000 ha) was developed following hierarchical principles of ecological unit mapping. Our primary objectives were to inspect the relations between direct and indirect biophysical variables in the prediction of valley bottom and stream type patterns, and to identify hydrologic subregions (based on these results) that had similar aquatic patterns for which consistent management practices could be applied. Realization of these objectives required: (1) stratified subsampling of valley bottom and stream type composition within selected sub‐watersheds, (2) identification of direct and indirect biophysical variables that were mappable across the basin and that exerted primary control on the distribution of sampled aquatic patterns, and (3) development of hydrologic subregion maps based on the primary biophysical variables identified. Canonical correspondence analysis indicated that a core set of 15 direct variables (e.g., average watershed slope, drainage density, ten‐year peak flow) and 19 indirect variables (i.e., nine subsection groups, four lithology groups, and six potential vegetation settings) accounted for 31 and 30 percent (respectively) of valley bottom/stream type composition variability and 84 and 80 percent (respectively) of valley bottom/stream type environmental variability within subsamples. The 19 indirect biophysical variables identified were used to produce an ecological unit classification of 7,462 subwatersheds within the basin by a hierarchical agglomerative clustering technique (i.e., hydrologic subregions were identified). Discriminant analysis indicated that 13 direct biophysical variables could correctly assign 80 percent of the subwatersheds to their indirect biophysical classification, thus demonstrating the strong relation that exists between indirect biophysical based classifications (ecological units) and the direct biophysical variables that determine finer‐level aquatic patterns. Our hydrologic subregion classifications were also effective in explaining observed differences in management hazard ratings across all subwatersheds of the basin. Results of this research indicate that ecological units can be effectively used to produce watershed classifications that integrate the effects of direct biophysical variables on finer‐level aquatic patterns, and predict opportunities and limitations for management.     

THE USE OF OVERWINTER DRAW DOWN FOR AQUATIC VEGETATION MANAGEMENT1

ABSTRACT: Overwinter draw down can be a useful technique for aquatic plant management. Its effectiveness depends largely on the susceptibility of nuisance species to draw down. A single overwinter draw down provided good control of aquatic plants in a flowage dominated by Potamogeton robbinsii Little additional control was gained by a second draw down the following winter. Rapid reinvasion of plants after draw down ceased dictates continued management. To avoid fish kills caused by low dissolved oxygen levels caution is advised when using overwinter draw down. The growth of Zizania aquatica was not negatively influenced by draw down. The influence on water quality of nutrient release from decaying vegetation and exposed bottom sediments was uncertain.     

CONTROLLING GROUND WATER DEGRADATION IN THE TULARE LAKE BASIN1

ABSTRACT This study examined the feasibility of extending the Accelerated Salt Transport (ASTRAN) method of groud water quality control to a complex, closed basin which is experiencing ground water quality degradation from irrigated agriculture (e.g., the Tulare Lake Basin in the Southern portion of the California Central Valley). A linear programming model was constructed and parametric analysis conducted which produced results with a “general appraisal” (or “level B”) degree of accuracy. The study concluded that a drainage water export drain is required in order to implement a long-term solution but that ground water degradation can be mitigated by a combination of the ASTRAN method and other measures even with existing entitlements and legal constraints.     

ROLE OF WATERSHED SUBDIVISION ON MODELING THE EFFECTIVENESS OF BEST MANAGEMENT PRACTICES WITH SWAT1

Distributed parameter watershed models are often used for evaluating the effectiveness of various best management practices (BMPs). Streamflow, sediment, and nutrient yield predictions of a watershed model can be affected by spatial resolution as dictated by watershed subdivision. The objectives of this paper are to show that evaluation of BMPs using a model is strongly linked to the level of watershed subdivision; to suggest a methodology for identifying an appropriate subdivision level; and to examine the efficacy of different BMPs at field and watershed scales. In this study, the Soil and Water Assessment Tool (SWAT) model was calibrated and validated for streamflow, sediment, and nutrient yields at the outlet of the Dreisbach (623 ha) and Smith Fry (730 ha) watersheds in Maumee River Basin, Indiana. Grassed waterways, grade stabilization structures, field borders, and parallel terraces are the BMPs that were installed in the study area in the 1970s. Sediment and nutrient outputs from the calibrated model were compared at various watershed subdivision levels, both with and without implementation of these BMPs. Results for the study watersheds indicated that evaluation of the impacts of these BMPs on sediment and nutrient yields was very sensitive to the level of subdivision that was implemented in SWAT. An optimal watershed subdivision level for representation of the BMPs was identified through numerical simulations. For the study watersheds, it would appear that the average subwatershed area corresponding to approximately 4 percent of total watershed area is needed to represent the influence of these BMPs when using the SWAT model.     

IMPLICATIONS OF A DRAWDOWN OF THE SNAKE-COLUMBIA RWER ON BARGE TRANSPORTATION1

ABSTRACT: The listing of the Snake-Columbia River salmon under the Endangered species Cut will lead to a set of river management changes aimed at species recovery. One measure almost certain to be implemented is a periodic river drawdown. A drawdown will speed fish migration downriver but will also temporarily close the river to barge transportation. Grain shippers in the region rely on the barge carriage to move a significant share of annual production to export elevators on the Lower Columbia. A number of other bulk commodities utilize barges as well. This study outlines the aggregate and distributional economic implications of a suspension of barge transportation resulting from a river drawdown.     

IN-LAKE WATER QUALITY MANAGEMENT PLAN FOR A RECREATIONAL LAKE IN CENTRAL ILLINOIS1

Johnson Sauk Trail Lake remains highly eutrophic, even though the watershed has long been returned to an undisturbed condition with permanent vegetative cover and with little or no land disturbance in the watershed. Internal regeneration of nutrients has been identified as the major source of nutrients to the lake. Lake destratification, selective harvesting and removal of weeds, and control of algal blooms using chelated copper sulfate application followed by potassium permanganate application have all been chosen as management techniques for improving water quality conditions in the lake. These in-lake techniques are considered not as palliative measures, but as necessary tools in enhancing the lake's water quality characteristics.     

USE AND EFFECTIVENESS OF MUNICIPAL WATER RESTRICTIONS DURING DROUGHT IN COLORADO1

ABSTRACT: Drought conditions in the summer of 2002 prompted several cities along Colorado's Front Range to enact restrictions on outdoor water use, focusing primarily on limiting the frequency of lawn watering. The different approaches utilized by eight water providers were tracked to determine the level of water savings achieved, measured as a comparison of 2002 usage to 2000 to 2001 average usage, and also based on a statistical estimate of 2002 “expected use” that accounts for the impact of drought conditions on demand. Mandatory restrictions were shown to be an effective tool for drought coping. During periods of mandatory restrictions, savings measured in expected use per capita ranged from 18 to 56 percent, compared to just 4 to 12 percent savings during periods of voluntary restrictions. As anticipated, providers with the most stringent restrictions achieved the greatest savings.     

ENHANCING THE EFFECTIVENESS OF PUBLIC PARTICIPATION IN DEFINING WATER RESOURCE POLICY1

ABSTRACT: Federal regulations require agencies administering water resource projects to inform and educate citizens so that they will understand and participate effectively in local programs. Government officials and public involvement specialists have proposed positive outcomes which should derive from agency educational efforts. Eleven interdependent educational goals are identified in this study such that achievement of each goal improves the likelihood of achieving others. Evaluations indicate that educational programs are inadequate and goals are not attained fully. The incorporation of mechanisms employed by professional educators is a potential remedy. Educational and social psychology contain an abundance of effective educational devices and methodologies appropriate for use in informal adult educational programs. An individualized educational program is recommended to meet the needs of a heterogeneous adult audience.