Thursday, November 14
10:30 am – 12:00 pm
Agenda subject to change.
Updated 1 November 2019
★ Denotes that the lead author is a student.
Moderator: Clelia Marti De Ocampo
University of Vermont, Burlington, Vermont
|10:35||Developing an Index of Habitat Quality for Maine Lakes
Jeremy Deeds and Doug Suitor
Maine Department of Environmental Protection, Augusta, Maine
Maine water quality standards mandate that lakes have natural habitat that supports aquatic life. DEP biologists have been developing a systematic evaluation of habitat quality in Maine lakes based on the physical habitat survey (PHAB) method from EPA’s National Lake Assessment. This method also provides a way to monitor lakes for the stressor of shoreline disturbance, which has not had a direct measure in the past. Using PHAB-derived observations and variables that statistically differentiate habitat condition in developed lakes and reference-quality lakes in Maine, a preliminary multi-metric index has been constructed to evaluate departure from the reference condition. Components of the multi-metric index include indices of habitat complexity, substrate quality, riparian quality and aquatic vegetation complexity.
|10:55||Assessing and Communicating the Status of Vermont’s Inland Lakes
Leslie Matthews and Kellie Merrell
Vermont Department of Environmental Conservation, Montpelier, Vermont
Vermont’s lake assessment program is designed to gather as much information as possible during a one-time visit to a lake. During a visit, we collect data on water chemistry, shoreline and littoral habitat, and inlet and outlet characteristics. We have leveraged condition indexes developed by EPA for the National Lake Assessment to create a Lake Report Card that gauges the status of a lake in comparison to other lakes in the state, ecoregion and nation. Results are communicated using various online tools developed using R markdown, interactive Google Maps, and other tools. Due to limited resources, we can only expect to conduct a full assessment of the physical, chemical and biological condition of a lake every 15 to 20 years. To maximize the information we can glean from a single visit, we are currently developing biological criteria using macroinvertebrates, macrophytes and/or sediment diatoms. Preliminary data and future plans for biological criteria development will be presented.
|11:15||Re-evaluating Recommended Phosphorus and Nitrogen Criteria for US Lakes and Reservoirs
Lester L. Yuan, Janice Alers-Garcia, Galen Kaufman, Jacques Oliver, Dana Thomas, and Brannon Walsh
US Environmental Protection Agency, Washington, District of Columbia
The US Environmental Protection Agency (EPA) published national recommendations for lake nutrient criteria in 2001 based on analyses of data available from different ecoregions of the United States. Since then, comprehensive data have been collected at the national scale, and the linkages between increased nutrient concentrations and different deleterious effects in lakes and reservoirs have been clarified. Here, we present an overview of EPA’s current effort to re-evaluate lake phosphorus, nitrogen, and chlorophyll a criteria. We first used an ecological risk assessment approach to select different endpoints that directly quantified whether a lake supported aquatic life, recreation, or use as a source of drinking water. For aquatic life support, we selected two endpoints: the ratio of zooplankton to phytoplankton biomass and the concentration of dissolved oxygen in the hypolimnion. For recreation and drinking water support, we selected microcystin concentration as the relevant endpoint. We then estimated empirical relationships between nutrient concentrations and each endpoint, and from these relationships, derived candidate numeric criteria. We also developed an approach that allows monitoring data collected at smaller spatial scales (e.g., within a single state) to be modeled in conjunction with the national scale data. These models provide the means for different states to derive state-specific criterion values based on locally collected data.
Moderator: David Neils
New Hampshire Department of Environmental Services, Concord, New Hampshire
|10:35||Drivers of Phosphorus Release and Sequestration in Eutrophic Waters and Their Sediments: Insight From Environmental Monitoring and Experimental Manipulation of Redox Front Dynamics
Andrew Schroth1, Greg Druschel2, Austin Wilkes1, Meagan Leduc1, Asim Zia3, Clelia Marti4, Donna Rizzo4, John Shukle2, and Martin Kurek2
1University of Vermont, Department of Geology, Burlington, Vermont; 2Indiana University-Purdue University, Indianapolis, Indiana; 3University of Vermont, Department of Community and Applied Economics, Burlington, Vermont; 4University of Vermont, Civil and Applied Engineering, Burlington, Vermont
Linkages between sediment-water interface (SWI). redox dynamics and phosphorus behavior are critical to understanding and managing algal blooms in shallow eutrophic lakes, where benthic fluxes can be dominant micro and macronutrient source in the euphotic zone. At eutrophic sites in Vermont’s Lake Champlain Basin, we have demonstrated that the release and sequestration of legacy phosphorus, as well as associated algal dynamics, are often driven by fluctuations in the position of the redox front relative to the s (SWI). However, this varies in both time and space. Here, through analysis of time series water column and sediment chemistry, coupled with experimental manipulation of SWI redox conditions in mesocosm experiments, we explore the relationship between environmental drivers(e.g., water column stability, riverine input, seasonality, biological production, ice cover), SWI redox front position, and the chemical partitioning of P in sediment and overlying bottom water. Our comprehensive analysis demonstrates that partitioning and release or sequestration of P in these sediment-water systems is highly dynamic and sensitive to an array of chemical, physical, and biological drivers of geochemical conditions across the SWI. Lake management initiatives aimed at reducing phosphorus loading from sediment or suppressing consequent potentially harmful cyanobacteria blooms must consider dynamic and potentially site-specific combinations of internal and external processes impacting the SWI geochemistry, which in turn drive sediment P concentration, composition, and mobility.
|10:55||★ Spatial and Temporal Variation in Anoxic Water in a Partially Stratified Temperate Lake
University of Massachusetts, Amherst, Massachusetts and Northeast Aquatic Research, Mansfield, Connecticut
Water quality monitoring was conducted at sixteen stations within a 947-acre lake in Connecticut. Weekly temperature, dissolved oxygen, and water clarity measurements were recorded at each station from April to October 2017. The goal of widespread monitoring was to determine the extent and duration of bottom-water anoxia in order to better characterize the impacts of internal phosphorus loading. While the central basin of the lake remained anoxic from mid-June through the end of August, the slightly shallower north and south basins experienced varied amounts of oxygen loss throughout the season. The anoxic boundary depth was not uniform across the lake, and certain areas of the lake experienced more hypoxia than others. The observed spatial and temporal variation in thermal stratification and subsequent oxygen loss leads to questions regarding the true dynamics of internal phosphorus loading on cyanobacteria blooms. Are weakly stratified and periodically anoxic shallow areas of lakes potentially more of a threat than true hypolimnetic internal loading?
|11:15||Comparative Lake Sediment Incubation Experiments to Determine the Phosphate Release and Effect on Water Quality After Treatment With Different Precipitation Materials
Limnological Solutions International, Bremen, Bremen, Germany
Sediment cores from two representative areas of Lake Werratal (Hessen/Germany) were incubated for three months to investigate lake sediment processes following treatments with phosphate precipitation materials. The experiment focussed on phosphate exchange processes between water and sediment using different capping measures and the influence of these measures on other water and sediment quality parameters.
At the start of the experiment, the content of metals and nutrients at different sediment depths were analysed for both representative areas. In addition, slices from all sediment horizons were tested using sequential phosphate analysis to determine the potentially releasable phosphate fractions of each sample.
An incubation experiment was then performed in which sediment was treated with iron chloride and nitrate. The phosphate binding efficiency, inorganic N pool and physico-chemical parameters of the treated sediment were determined, and the results compared to cores that had been treated with Phoslock and poly aluminium chloride.
All products were able to bind phosphate however secondary effects were observed in some products in terms of pH, conductivity and ammonium concentrations. Ammonium concentrations increased due to reductive processes on nitrate and organic matter in all cores while the pH decreased in the metal salt treatments. The sustainability of the phosphate binding reagents needs further investigation in terms of the structure and longevity of the sediment capping.
|11:35||Internal Phosphorus Loading Models: A Critical Review
Freshwater Research, Baysville, Ontario, Canada
Internal phosphorus (P) load as phosphate released from lake bottom sediments is an important nutrient source that can trigger cyanobacteria blooms. Its quantification can be complicated and is affected by the thermal stratification status of the lake; therefore, modeling is often the approach to incorporate internal load into water quality predictions. This review critically evaluates two basically different model classes: (1) detailed, process-based models (“mechanistic models”) often developed for individual lakes and (2) empirical, cross-system models developed on data of many lakes over a wide range of conditions. Performance, testability, and other model characteristics are described for a wide-range of published models. Simpler, empirical models predict internal load from sediment P release rates and the area and time involved in release, while complex models often incorporate seasonal P fluxes. Steady state mass balance models just distinguish between annual P fluxes to and from the sediments to assess internal load, while more complex models can incorporate time and spatial dynamics. The main application of internal load estimates is the prediction of lake total P concentration for different periods. Internal load is becoming more important because of synergistic effects of temperature increases on P release rate and area, as well as changes in thermal stratification, all of which is predicted in many climate change models. Model choice depends on data availability, financial and technical resources, and the application history of specific models, while testability and verifiability combined with the principle of parsimony are considered most important.
Moderator: Todd Tietjen
Southern Nevada Water Authority, Las Vegas, Nevada
|10:35||Nuisance Phytoplankton Blooms Related More to Hydrography Than to Phosphorus
Shannon Brattebo1, Gene Welch2, BiJay Adams3, and Jeremy Jenkins3
1Tetra Tech, Inc., Spokane, Washington; 2Tetra Tech, Inc., Seattle, Washington; 3Liberty Lake Sewer and Water District, Liberty Lake, Washington
The occurrence of nuisance level phytoplankton blooms during 2000–2016 in relatively shallow (7 m mean depth) Liberty Lake in eastern Washington was due more to water column stability, climate, and hydrology than total phosphorus (TP) concentration. Relative thermal resistance to mixing (RTRM) averaged 72.7 ± 30 for the bloom years and 44.8 ± 14 for the non-bloom years. The five summers with highest RTRM values all had nuisance blooms. Three other years also had nuisance blooms with low RTRM, but with below normal precipitation and little outflow during the spring. There was also little difference in average summer TP between bloom and non-bloom years – 23.1 vs 24.1 µg/L. Transparency also decreased with increased RTRM, indicating an increase in algal biomass. While internal loading was substantial during summer, at 80% of total, sediment-P inactivation was not recommended, although it was the preferred management alternative, because TP concentration was not exceptionally high and nuisance phytoplankton blooms were more related to hydrography than to phosphorus.
|10:55||★ Predicting the Occurrence of Harmful Algal Blooms Resulting From Wind-Related Metalimnetic Entrainment of High Phosphorus Hypolimnetic Water
Sarah H. Burnet and Frank M. Wilhelm
University of Idaho, Moscow, Idaho
Wind is a primary factor influencing the physical translocation of packets of water, and the nutrients in them, in lakes and reservoirs. If phosphorus (P) derived from internal loading in the hypolimnion reaches surface waters it can alter the nitrogen:phosphorus (N:P) ratio that determines the species composition of algal communities. Low N:P ratios are known to promote the occurrence of blooms of toxic cyanobacteria called harmful algae blooms (HABs). We aim to test the hypothesis that it is possible to predict the timing and occurrence of HABs from relationships between wind speed, time of year, depth of thermal stratification, and the water column phosphorus concentration. We plan to use Willow Creek Reservoir (WCR) in Heppner, Oregon as a case study to quantify the load of P transferred to surface waters by wind mixing events, given it currently experiences severe annual hypolimnetic anoxia and high hypolimnetic P loading that are hypothesized to result in HABs. Additionally, we aim to understand the physical drivers of these processes including the duration and strength of a wind event needed to cause metalimnetic entrainment. The potential to predict the occurrence of algae blooms will benefit lake managers that are responsible for managing lake access and ensuring the health and safety of the public.
|11:15||Big Problems, Limited Data: Going From 0 to 60 to Assess and Address HABs, Pathogens, Emerging Contaminants, and More in a Problematic Coastal Pond
ESS Group, Inc., East Providence, Rhode Island
Bartlett Pond is a 30-acre coastal pond that discharges to a saltwater beach in Plymouth, Massachusetts. Although impairment of the pond and its outlet had been suspected for decades, evidence was primarily anecdotal until 2018, when health advisories were posted due to cyanobacteria blooms and high bacterial counts. Following this, the Town commissioned a comprehensive study of the pond and its watershed, which includes an improbable patchwork of dense neighborhoods, forested hills, and the largest freshwater wetland restoration project in the state.
Although existing data were limited, the presence of various risk factors implied a high likelihood of multiple important sources of nutrients and bacteria. Additionally, the geographic setting of the pond suggested the potential for complex interactions between fresh and saltwater influence, surface and groundwater inputs, aquatic macrophytes and algae, and external and internal loading, each combination of which could yield different environmental consequences for the pond, beach, and community. Therefore, our approach consisted of frontloading the assessment with a comprehensive array of sampling efforts at the pond to identify the range of potential sources. This was followed by targeted efforts to track the identified pollutant issues to their source(s) in the watershed or within the pond.
The data from these study components were used to develop a one-dimensional model of in-pond water quality and biological response over time. In turn, this model and the watershed source tracking results are being used to inform development and implementation of mechanical, chemical, biological, and policy-based lake and watershed management recommendations.
|11:35||Save Time, Money, and Headaches With a Multi-Product Approach to HAB Management Utilizing Targeted Spot Treatments
Elizabeth Crafton1, Jessica Glowczewski2, Don Ott3, and Teresa Cutright3
1Hazen and Sawyer, Columbus, Ohio; 2Akron Water Supply, Akron, Ohio; 3University of Akron, Akron, Ohio
Seasonal potentially harmful algal blooms (HABS) can impair source water quality, which can be costly to address in a water treatment facility. Algaecide application is a common short-term management practice used to control potential HABs in drinking water sources. After bench-scale and field testing in 2017, a multi-product, full season management plan was implemented in 2018. This plan utilized two target in-reservoir treatment areas, one at a tributary entrance (historically documented HAB formation area) and one near the intake (addressing low levels of confirmed accumulation). The historically active area was treated with hydrogen peroxide-based product, PAK27. The intention of PAK27 application was to shift the dominance away from cyanobacteria to achieve prolonged suppression and reduced metabolic activity. Targeting an historically active site reduced had the intention of reducing the observed accumulation near the intake. Low dose copper treatments were utilized as need at in this area as an additional layer of protection from HAB related contaminants. This management plan proved successful, resulting in approximately $161,000 total savings in chemical cost within the treatment plant and in reservoir, with $15,000 savings in algaecide, $57,000 in Alum, and $90,000 PAC. The shift in dominance and subsequent prolonged suppression from PAK application was captured by a continuous monitoring location in the historical active area and microscopic analysis, which persisted for ~6–7 weeks post-treatment.
Moderator: Steve Souza
Clean Waters Consulting, LLC, Ringoes, New Jersey
|10:35||Making Money on Lake and Reservoir Restoration: A Case History of Hypolimnetic Oxygenation in California
University of California, Berkeley, California
Lake and reservoir cleanups are driven by a need to meet a water quality standard like TP, Secchi depth, or malodor. Rarely are they driven directly by the need to make a profit. Nonetheless, it would be nice if they did. Economists use a benefit: cost ratio to determine if projects like a road, library or airport are worthwhile. Usually, anything much of a b/c ratio of unity passes the test for public works, but how do our lake and reservoir restorations fit in? In 1993, following large Chinook salmon losses in a hatchery upstream, a new but seemingly costly technique, the Speece Cone, was installed in Camanche Reservoir, California. The cone is definitely an engineered device. A large pump sucks in deep anoxic water and mixes it with pure oxygen gas to dissolve in the cone. The resulting plume of highly oxygenated water is diffused to suitable levels and sent out to (hopefully) oxygenate the deep water and provide lots of benefits. The benefits range from preventing internal nutrient loading, removing toxic hydrogen sulfide, and increasing fish habitat. The costs are the new infrastructure and its long-term maintenance (oxygen & electricity. At Camanche Reservoir the b/c ratio was over 20 – possibly the highest in the environmental restoration world. Is that the way of the future? Special circumstances including increases in valuable adult Chinook salmon, a 600% increase in the endangered Steelhead trout, resumption of hydropower generation in summer, and more water flexibility in droughts bolstered the b/c ratio but are potentially likely elsewhere.
|10:55||Comparing Summer 2018 to 2019 Water Quality Data, North Lake, Sweet Valley, Pennsylvania
Holly Frederick, Scott Heffelfinger, Kaitlin Sutton, Jillian Weston, Michaela Fehn, Nicole Hart, Seth Platukis, and Jacob Schall
Wilkes University, Wilkes-Barre, Pennsylvania
Analysis of water quality conditions in North Lake, Luzerne County, Pennsylvania was performed between May 2018 and November 2018 and beginning in May 2019 and is ongoing. This lake has a total surface area of 38.9 acres, a watershed area of 137 acres, a volume of 1.25 × 108 gallons and a maximum depth of 6.8 m. Eutrophic conditions have been a concern at the lake and an internal diffusion system is maintained. A Kemmerer sampler was used to collect individual water samples 1 m and 5.5 m below the surface at the deepest point and at various locations in 2018. In 2019 the samples were taken from 1 m, 5.5 m and 6.25 m below the surface focused on the deepest point with no internal diffuser and the deepest point with a diffuser. Sonde units also monitored the temporal water quality conditions at these depths. Field measurements included Secchi disc measurements, temperature, pH, dissolved oxygen and identification of runoff locations. Laboratory analysis included nitrate, total nitrogen, ammonia, soluble reactive phosphate, total phosphorus, solids analysis as well as an anion suite on the ion chromatograph. In 2018, the total phosphate range was 0.096–0.50 mg/L, the soluble reactive phosphorus values ranged between 0.018 and 0.098 as phosphate, the nitrate values ranged from 0.26 to 1.05 mg/L as nitrate. In the summer of 2019 total phosphate range was 0.016–0.73 mg/L, the soluble reactive phosphorus values ranged from below the detection limit to 0.041 as phosphate, the total nitrogen ranged from 0.5 to 7.6 mg/L as N, while nitrate values ranged from below the detection limit to 0.384 mg/L as nitrate. The variability between the depths and the presence of the diffuser define important differences in the data set.
|11:15||Algae Mitigation Using Air Nanobubbles
Jason Verhoef and Andrea White (presented by Christian Ference)
Moleaer, Torrance, California
Nanobubbles (< 400 nm diameter) exhibit unique properties: high surface tension, negative charge, persistence/stability, neutral buoyancy, high surface area by volume, and Brownian motion, providing higher oxygen transfer efficiencies (OTE) than traditional aeration methods (> 85%). This increased OTE is independent of water depth allowing the use of nanobubbles to maintain aerobic conditions throughout the footprint of a water body and vertically throughout the water column. A velocity based nanobubble generation technology was tested at a 1.3-acre lake in Florida with persistent algae blooms despite monthly treatments of copper sulfate and installation of two 1/2 hp piston compressors adding 8 CFM of air at 20 PSI via air stones. A nanobubble system running at 200 GPM and with an air flow rate of 20 CFH at 120 PSI replaced chemical treatment and air stones. Dissolved oxygen levels were taken before and during 6 weeks of nanobubble aeration at water depths of 2’ and 8’ near the nanobubble injection point, the opposite end of the lake and the center of the lake. An even distribution of oxygen throughout the lake was observed with a 100% increase near the sediment and > 35% increase near the surface. No algae blooms were observed during the nanobubble study and there was a noticeable decomposition of the organic material in sediment. After ending the nanobubble study the algae blooms had begun to return within two months suggesting at this site the nanobubbles did not eradicate the algae but mitigate algae growth by preventing nutrient recycling under anaerobic conditions.
Moderator: Terry McNabb
Aquatechnex, LLC, Bellingham, Washington
|10:35||The Effects of Winter Water Level Drawdown on Water Quality and Aquatic Macrophytes
Wendy C. Gendron1 and Bruce Leicher2
1Aquatic Restoration Consulting, LLC, Ashburnham, Massachusetts; 2Bare Hill Pond Watershed Committee, Harvard, Massachusetts
Bare Hill Pond (BHP) in Harvard, Massachusetts is listed as impaired for Noxious Aquatic Plants and threatened due to high phosphorus concentration. The pond is naturally 200 acres and was enhanced in 1838, increasing the area to 321 acres. The “weed” problem was apparent by the mid-1950s. The BHP Watershed Committee was established in response to the weed problem and began applying herbicides and implementing winter water level drawdowns (DD) in the 1960s. The gravity DD was limited to 3.5–4.0’. These techniques were used throughout the 1970s and 1980s until a moratorium was placed on herbicide use in 1983. Non-native milfoil, fanwort and water chestnut remained problematic. The Committee searched for additional non-chemical alternatives and began mechanical harvesting but relief was short lived and may have spread fanwort. The Committee constructed a pump house to mechanically lower the water level to achieve a 7’ DD. Biologists have monitored changes in plant community and water quality since the extended DD began in the winter of 2006–2007. Results of 11 years of monitoring (pre-post extended DD) indicate that overall plant coverage remained consistent, but density and community composition has changed. Phosphorus concentrations are variable but improved since the 1990s. There are no changes in clarity, no measurable negative impacts to adjacent wetlands, no expansion of non-desirable emergent species and no observable negative impacts to frogs, turtle and mussels. Mammalian species are still abundant. The authors note that these changes are not statistically quantified due to limited data prior to the extended DD.
|10:55||Successful Physical Management of AIS in the Drinking Water Reservoirs Serving Greater Boston, Massachusetts
Joy Trahan-Liptak1 and John J. Gregoire2
1Massachusetts Department of Conservation and Recreation, Division of Water Supply Protection, West Boylston, Massachusetts; 2Massachusetts Water Resources Authority, Boston, Massachusetts
Aquatic invasive species have the potential to significantly degrade water quality. The presence and proliferation of these species are therefore a major concern for drinking water suppliers such as the Massachusetts Water Resources Authority (MWRA) which provides drinking water to 2.5+ million people and thousands of industrial users in and around the greater Boston area. The Massachusetts Department of Conservation and Recreation, Division of Water Supply Protection (DWSP) manages the source waters and watersheds including the 1,673-hectare Wachusett Reservoir. Invasive aquatic plant management in this reservoir system was initiated in 2001 following the discovery of Eurasian Milfoil (Myriophyllum spicatum) and Fanwort (Cabomba caroliniana), due to the threat these plants present to water quality and the reservoir ecosystem. A robust management program has since evolved, coupling extensive monitoring with exclusively physical control methods which have included benthic barriers, diver assisted suction harvesting (DASH), and hand-harvesting. The current methodology involves multiple seasonal rounds of harvesting within a grid system and subsequent checks by a separate quality assurance dive crew and DWSP biologists. This approach has succeeded in > 98% reduction in invasive plant density within the management areas and successful recolonization of diverse native species. Additional monitoring includes plant surveys and the creation of plant biovolume maps. Finally, the program also includes additional components such as education, boat and equipment decontamination, exclusion, and a rapid response plan.
|11:15||Forty Years of Water Chestnut Management on Lake Champlain – Miles vs. Money
Vermont Department of Environmental Conservation, Lakes and Ponds Program, Montpelier, Vermont
The states of Vermont and New York have an extensive history of managing water chestnut in Lake Champlain since it was first discovered in the 1940s. While a 1970 report outlined optimistic results of the management efforts whereby the population was reduced so much so that it was difficult to find plants, by the late 1970s the population had exploded, forming dense mats that made boat travel difficult through the narrow passes in Southern Lake Champlain. Since that time, the Vermont Department of Environmental Conservation (VTDEC) has led the Lake Champlain Water Chestnut Management Program that includes mechanical and hand harvesting operations on both sides of the lake, overseeing approximately 1,300 shoreline acres. The amount of funding and support throughout the years has experienced highs and lows, and with it a demonstrable increase or decrease in the miles of intense mechanical harvesting needed to control the dense populations. Entering almost twenty years of mostly stable results, a sustainable and long-term effort is necessary though difficult to maintain. Within this presentation we’ll review a quick history of the Lake Champlain Water Chestnut Management Program, the documented results of miles vs. money, and the contemporary tools used at present to monitor the effectiveness of the harvesting operations.