Wednesday, November 13
8:30 am – 10:00 am

Agenda subject to change.
Updated 1 November 2019

★ Denotes that the lead author is a student.

 

D1: Source Water Protection I

Moderator: Brad Hufhines
Beaver Water District, Lowell, Arkansas

8:35 Surface Water Source Protection in Vermont
Liz Royer1, Diana Butler1, and Kira Jacobs2
1Vermont Rural Water Association, Essex Junction, Vermont; 2US Environmental Protection Agency Region 1, Boston, Massachusetts

Since 1992, the Vermont Department of Environmental Conservation (DEC) has required most public drinking water systems to draft and implement source water protection plans. Vermont is one of the few states that mandates plans for both surface water and groundwater supplies. In addition to the 12 municipal water systems drawing from Lake Champlain, there are over 20 community water suppliers using a variety of surface water drinking sources in every corner of the state. This presentation will explore all aspects of source protection planning for surface water supplies in Vermont.

The Vermont Rural Water Association (VRWA) is a nonprofit organization that provides training and technical assistance to public water and wastewater systems. Specific to source protection, VRWA partners with local, state, and federal agencies to help water systems with planning, management, and implementation activities. Over the past few years, VRWA, along with the Vermont DEC and US EPA Region 1, have been targeting outreach on source protection to land use planning professionals. Surface water source protection tactics can be integrated into zoning and development regulations, town and regional planning efforts, and hazard mitigation and emergency response strategies. In addition, water quality concerns from agricultural runoff have been in the forefront of state and regional discussions. This presentation will specifically consider opportunities for collaboration to improve water quality in Vermont’s sources of drinking water including Lake Champlain, reservoirs, and inland lakes and ponds.

8:55 CWD’s Long Term Source Water Strategy within the Shelburne Bay Watershed
Joe Duncan
Champlain Water District, South Burlington, Vermont

The Champlain Water District (CWD) supplies drinking water to 12 municipal systems in northwestern Vermont. Established in 1973, CWD’s Water Treatment Plant was built with the goal of treating water from Lake Champlain and providing wholesale drinking water to its member systems. CWD’s water supply is located in a deep-water canyon within Shelburne Bay. This presentation will review how CWD chose its current intake site, as well as the source protection strategies implemented within the watershed to manage CWD’s high quality water source.

9:15 Source Water Protection Challenges in New Hampshire’s Multi-Use Water Supply Lakes (or the Uses of MUWSLs)
Paul Susca and Pierce Rigrod
New Hampshire Department of Environmental Services, Concord, New Hampshire

Water-based recreation is important to New Hampshire’s tourism economy and to residents’ quality of life. Many of the state’s water supply lakes and/or their watersheds are used for water- or land-based recreation, and some have developed shorelines. Source water protection – the management of water bodies and wells used as sources by public water systems – is particularly challenging for these multi-use water supply lakes (MUWSLs). Aspects of the inherent conflict among uses of MUWSLs include potential pathogenic contamination associated with body-contact recreation, the use of herbicides to control invasive plants that interfere with recreation and esthetic values, the potential for the release of fuel from motor boats, and nutrient loading associated with shoreline development. Even where forward-thinking water suppliers own substantial amounts of watershed land, recreational uses such as ATV trails and horseback riding are concerns.

Approaches to source water protection for MUWSLs vary from one lake to the next across New Hampshire and reflect the history of the state’s industrial and post-industrial development. This presentation will review the protection status of the state’s water-supply lakes and the water quality concerns associated with recreation and examine several cases where conflicting uses have been addressed, although not necessarily resolved. Ongoing efforts by the state’s drinking water program and lake program will be described, with a focus on ongoing challenges such as shoreline development and the potential for harmful cyanobacterial blooms, and unanswered questions such as how to most effectively engage both water suppliers, property owners, and other lake users.

9:35 Roaring Brook Reservoirs: Can Timber Harvest and Drinking Water Protection Both Occur?
Don Kretchmer1 and Peter Walker2
1DK Water Resource Consulting LLC, Wolfeboro, New Hampshire; 2VHB, Bedford, New Hampshire

The Roaring Brook watershed includes two reservoirs in series that provide drinking water to the City of Keene, New Hampshire. The city has owned the reservoirs and most of the watershed for over 100 years. The reservoirs are a primary drinking water source however they have not been operated under a formal management plan. Recent discussions about the possibility of harvesting timber over much of the watershed precipitated a more careful look at water quality and watershed management. A water quality monitoring program was conducted to support a watershed/reservoir modeling effort. The modeling effort provided insight into the likely water quality impacts of several management scenarios including access road stabilization and a staged timber harvest over much of the watershed. Phosphorus, chlorophyll a, transparency and the likelihood of algal blooms were all used as metrics to evaluate scenarios. A monitoring program to document future water quality was included in the plan.

 

D2: Salt II – Canada

Moderator: Kris Stepenuck
University of Vermont, Burlington, Vermont

8:35 Winter Management of Snowmelt Runoff to Prevent Freshwater Salinization
Isabelle R.B. Fournier1,3, Rosa Galvez2,3, and Warwick F. Vincent1,3
1Department of Biology, Laval University, Quebec City, Quebec, Canada; 2Department of Civil and Water Engineering, Laval University, Quebec City, Quebec, Canada; 3Center for Northern Studies (CEN), Quebec City, Quebec, Canada

Freshwater salinization is a growing concern throughout the world. Over the last few decades, the concentrations of Na, Cl, Ca, Mg and K have greatly increased in many north temperate lakes and rivers as a result of deicing materials applied to their surrounding roads in winter. This salinization has the potential to affect ecosystem functioning and may compromise drinking water quality. Road deicing is difficult to control because it is often vital for vehicle safety, and there is no obvious alternative that meets the same criteria of cost, effectiveness and absence of apparent health impacts. It is unlikely that that salt-based deicing will be discontinued in the near future, and management strategies require an improved understanding of the distribution, flow pathways and timing of the road salt fluxes through the landscape. In the present study, we focused on the catchment of the Saint-Charles River and its associated reservoir, which provide drinking water for Quebec City, Canada. Major ion concentrations were measured in river waters and snowbanks along roads in sub-catchments of various urbanization levels, and during the same winter-spring period, a mooring system was installed in the Lake Saint-Charles reservoir to continuously record electric conductivity. There were large differences in concentration as well as in the temporal behavior of ions between urbanized and forested watersheds. Variations in conductivity in the urban rivers and the reservoir were well correlated with those in the snow. The results indicate that management of roadside snowmelt runoff during winter would prevent salinization.

8:55 Sedimentary Cladoceran Assemblages and Zooplankton Communities of Shallow Lakes in South-Central Ontario (Canada): Relationships to Road Salt Runoff and Other Measured Environmental Variables
Robin Valleau1, Andrew Paterson2, and John Smol1
1Paleoecological and Environmental Assessment and Research Laboratory (PEARL), Department of Biology, Queen’s University, Kingston, Ontario, Canada; 2Dorset Environmental Science Centre (DESC), Ontario Ministry of the Environment, Conservation and Parks, Dorset, Ontario, Canada

The more than 2000 lakes in the Muskoka River Watershed (MRW) of south-central Ontario provide drinking water to many full-time and seasonal residents; however, increasing urbanization and associated inputs of chloride from road salt can salinize these fresh waters and threaten the many ecosystem services they provide. Lakes impacted by road salt may have chloride (Cl) concentrations up to 300% higher than natural conditions. When compared to the provincial average, chloride concentrations in Muskoka lakes are relatively low, and well below the Canadian Water Quality Guideline (CWQG) for Cl for the prevention of harm to aquatic life (120 mg/L). However, recent laboratory experiments show enhanced sensitivity to Cl toxicity for some zooplankton species, particularly at low food levels. Thus, low-nutrient lakes within Muskoka may be particularly sensitive to road salt impacts. Here, we examine subfossil Cladocera remains preserved in surface sediments samples and composite zooplankton communities collected from net tows across a gradient of chloride concentrations from 0.2 to 137.0 mg/L. We examine zooplankton data in 43 oligo – to mesotrophic shallow lakes in the MRW to evaluate relationships among species assemblages, Cl concentrations, and other measured environmental variables. Chydorus brevilabris abundance in these lakes was significantly correlated to Cl concentration in both surface sediments and net tows, with greater relative abundances found in lakes with higher Clconcentrations. The subfossil remains of Eurycercus sp., Alonella excisa, and Ophryoxus gracilis were also significantly and positively correlated to Cl concentration. These survey results agree with previous downcore paleolimnological analyses of five ‘salty’ lakes in the MRW. As Clconcentrations continue to increase in many regions, there will likely be impacts on aquatic ecosystems, even at chloride concentrations below the CWQG.

9:15 Factors Influencing Chloride Concentrations in Lakes Located in Halifax, Nova Scotia, Canada
Tessa Bermarija, Meggie Letman, Richard Scott, Jenny Hayward, and Rob Jamieson

Centre for Water Resources Studies, Dalhousie University, Halifax, Nova Scotia, Canada

Increasing lake chloride (Cl) concentrations due to winter road salt application are a growing concern across temperate North America. Many regions have seen Cl levels that consistently exceed national guidelines. In Canada, these guidelines are set at 120 mg/L for chronic, and 640 mg/L for acute exposure. Factors having the most influence on these increasing Cl levels have proven to be unique to each lake and watershed. A long-term study conducted in Halifax, Nova Scotia on nine lakes tracked Cl levels for over 35 years and showed a correlation between the percent of urban landcover within a watershed and Cl concentration. The influence of lake morphology, flushing rate, road length, and road density, among other variables, were also investigated, but were not found to be strong predictors of Cl levels. A threshold value was observed, whereby if greater than 25% of the watershed was developed, Cl levels tended to exceed the CCME guideline for chronic exposure. The results from this initial study are being validated using data from a regional lake sampling program conducted from 2006–2011, where 60 urban and suburban lakes were sampled 2–3 times per year. Other potential contributing factors, including impervious connectivity, are also being assessed, within this regional analysis. Results of these combined studies may help to inform decision making surrounding land use planning and road salt BMPs for the protection of lakes against potentially damaging Cl levels.

9:35 Climate Change and Nutrient Sensitivity Increase Threat of Chloride in PreCambrian Shield Lakes
N.D. Yan1, M. Celis-Salgado2, S. Arnott2, A. Paterson3, R. Valleau2, and N. Hutchinson4
1York University, Toronto, Ontario, Canada and Friends of the Muskoka Watershed, Bracebridge, Ontario, Canada; 2Queens University, Kingston, Ontario, Canada; 3Ontario Ministry of Parks Environment and Conservation, Dorset, Ontario, Canada; 4Hutchinson Environmental Sciences Ltd. Bracebridge, Ontario, Canada

Muskoka’s large population of lakes supports an important recreational economy that is serviced by a network of ~800 km of highways that are maintained over five winter months. Road salt application is increasing chloride concentrations in our lakes – chloride concentrations are positively and significantly correlated to road density. All developed lakes in Muskoka have shown increased Cl levels while undeveloped lakes have seen decreases. Lake Muskoka, the largest lake (12,100 ha) is at the bottom of a very large watershed (466,000 ha). Cl levels increased from 2.6 to 6.4 mg/L between 1983 and 2016, equivalent to a loading ~ 12,000 tonnes. The Canadian WQG for Cl is 120 mg/L. It is exceeded in one Muskoka lake adjacent to a major highway and urban area where paleolimnological reconstructions show alterations in the cladoceran community in this lake since the onset of road salting. Recent research shows substantial differences in Cl toxicity between Daphnia species and species lines and that Cl toxicity is highly dependent on the nutrient status of test animals. The existing guideline of 120 mg/L is not protective of Cladocera in oligotrophic lakes in which their food supply, and resultant nutrient condition, makes them more sensitive to Cl. A guideline of 10 mg/L is required for protection of aquatic life in oligotrophic PreCambrian Shield lakes, based on the sensitivity of Cladocera. While municipalities have reduced road salt applications there is less progress on management of private properties, and threats of personal injury liability encourage over application. Our warming climate is increasing the number of freeze-thaw cycles over the winter, increasing the need to manage winter road icing and resultant salt applications.

 

D3: Phosphorus Inactivation II – Aluminum

Moderator: Harry Gibbons
Tetra Tech, Inc., Seattle, Washington

8:35 Evolution of Sediment Inactivation in Florida Lakes – Impacts on Longevity
Harvey H. Harper

Environmental Research & Design, Inc., Orlando, Florida

More than 45 sediment inactivation projects have been conducted in Florida since 1981 with lake surface areas ranging from 8 to > 1,000 acres. The majority of applications were conducted using alum only, with approximately 40% requiring supplemental buffering agents such as sodium aluminate or lime. Dosage calculations for all projects have been based on concentrations of available sediment P (ASP), defined as the sum of saloid P (soluble + easily exchangeable) plus Fe-bound P. Molar Al:P (available sediment P) ratios have ranged from 2 in early projects to > 10 in recent years. Dosage calculations for recent projects have used a variable ratio based on ASP with higher Al:P ratios used at lower ASP concentrations. Monitoring data suggest that the use of sodium aluminate or sodium hydroxide as a pH buffer may reduce the application longevity, so current applications are divided into multiple treatments spaced 4–8 months apart to allow alkalinity to be restored naturally.

Long term pre- and post-treatment water quality data are available for 20 of the treated lakes with applications conducted from 1995–2018. Each of the treated lakes exhibited both immediate and long-term improvements in water quality, but longevity has been variable. Each of the applications resulted in stable water quality improvements for a minimum of 5 years before signs of decreasing effectiveness, while some lakes have maintained stable post treatment water quality for 10–20 years. Significant factors regulating longevity appear to be the significance of internal recycling as a nutrient source, molar Al:P ratios, use of pH buffers, sediment concentrations of available P, areal alum application rate (g/m2), and number of applications. The data suggest that properly conducted sediment inactivation applications can maintain improved water quality for a minimum of 10 years in most cases.

8:55 Alum Dosage and Application Strategies: Theory, Practice, and Recent Experiences
William F. James

University of Wisconsin – Stout, Menomonie, Wisconsin

Application of aluminum salts to bind sediment mobile phosphorus (P) and control internal P loading in eutrophic lakes has been used with varying degrees of success for nearly 50 years. Current Al dosing strategies are based on inactivation of sediment mobile P concentrations (i.e., loosely-bound P, iron-bound P, and-or labile organic P) and an Al:P binding ratio that is estimated via laboratory assays or determined from lake sediments treated with Al many years ago. However, P binding affinity and capacity can decline by up to 75% within months without exposure to P due to crystallization of Al(OH)3. Thus, Al application strategies should be designed to foster immediate P exposure to increase P saturation onto the Al floc and reduce crystallization. These strategies include 1) timing Al application to coincide with the development of hypolimnetic anoxia and diffusive P flux from sediment, 2) applying Al during peak hypolimnetic P accumulation in late summer, and 3) splitting the Al dose into smaller concentrations that are applied over several years. The former two strategies promote immediate exposure of the Al floc to P while the latter strategy promotes saturation of Al(OH)3 binding sites with mobile P. Recent experiences and results using these application strategies on several lakes are discussed.

9:15 Multi-Year Study of Six Rhode Island Water Supply Reservoirs With Focus on HAB Control With Alum
Carl Nielsen

ESS Group, Inc., East Providence, Rhode Island

The Providence Water Supply System relies on a watershed network of six surface supply reservoirs within one of the most densely populated states in the county, yet this system provides some of the highest quality water to its customers. A multiyear investigation was undertaken to assess each of the health of each of the reservoirs for the first time ever beginning in 2009 culminating in a comprehensive two-year analysis of the 1,700-acre main supply reservoir, Scituate Reservoir, between 2016 and 2018. Assessments included surface and groundwater quality, sediment quality, macrophyte and algal community composition, wildlife impacts (beaver and goose), and nutrient loading analysis.

Each of the five upper watershed reservoirs were assessed a second time five to eight years later to document changes within these systems. In the interim years, Providence Water implemented a variety of management actions within the watershed including construction of stormwater BMPs, land purchases, and even the first full-lake alum treatment in Rhode Island at the most impaired reservoir to manage harmful algal blooms (HABs) that frequently occurred at one of the reservoirs. Although development pressure continues to be a challenge to maintaining water quality, Initial findings suggest that the use of an alum treatment to mitigate impacts from phosphorus was a successful approach to quickly curtail HABs while other watershed measures are pursued.

9:35 Low Dose Aluminum Treatments to Manage Water Clarity in Two Urban Lakes
Ken Wagner

Water Resource Services, Wilbraham, Massachusetts

Woodridge Lake and Woodridge Pond in West Hartford and Farmington, Connecticut are relatively small (26 and 11 ha), shallow (maximum depth < 3 m), constructed waterbodies with highly urbanized watersheds. Problems with algae blooms and rooted plants have plagued these ponds for several decades and use of herbicides to control macrophyte nuisances has shifted the balance toward intense blooms of algae, including cyanobacteria during summer. With an ongoing lack of success in getting state and municipal agencies to participate in watershed management despite obvious and inexpensive opportunities, the lake association turned to low dose aluminum treatments to improve summer water clarity in these waterbodies, which are popular for swimming and non-motorized boating. Monitoring indicated that P concentrations rose from spring values of around 30 µg/L to summer values > 200 µg/L, despite low inflows from the watershed during much of this time. Both internal recycling and watershed inputs from larger storms were implicated. Al doses of 1–2.5 mg/L were applied once in summer 2015 and twice in each summer of 2016–2018. Summer P concentrations declined substantially, and cyanobacteria blooms were eliminated. Green algae mats have become the primary problem, not being affected by either the rooted plant control efforts or the water column P inactivation, but conditions have been markedly improved by this relatively inexpensive approach. Where watershed management is compromised, P inactivation as a maintenance measure can help meet water quality use goals.

 

D4: Paleolimnology I – HABs

Moderator: Tom Whitmore
University of South Florida St. Petersburg, St. Petersburg, Florida

8:35 Paleolimnological Reconstruction of Harmful Algal Bloom Trends in Texas Reservoirs
Lane Allen1, Victoria Chraibi1, Jeff Brady2, Janice Speshock1, and Ryan Morgan3
1Department of Biological Sciences, Tarleton State University, Stephenville, Texas; 2Texas A&M AgriLife Research, Stephenville, Texas; 3Department of Geoscience, Chemistry and Physics, Tarleton State University, Stephenville, Texas

Most Texas reservoirs are younger than 150 years and have scant records related to their ecology. While HABs are being reported more frequently, it is unclear how long this trend has been developing in Texas as well as unclear as to the fundamental mechanisms causing the trend. This study employed paleolimnological methods to retrieve sediment cores from three reservoirs in Texas, two of which have had recently reported harmful algal blooms caused either by cyanobacteria or Prymnesium parvum. Sediment was dated with a combination of Cs-137 radioisotopes, fire charcoal records, and sedimentation rate records maintained by the state. DNA stored in the sediment was analyzed to identify the presence of cyanobacteria and P. parvum and approximate their abundance over time. In areas where peak abundance was observed, further genetic analysis for algal toxins identified whether or not those blooms became harmful. To identify biotic and abiotic factors that may result in HAB events, diatom subfossil assemblages were used to infer environmental conditions such as nutrient status and lake level. Sediment was characterized by XRF and XRD to identify sediment sources and infer environmental chemistry. Understanding past trends aid in creating models to predict HABs for lake management.

8:55 Understanding Factors Influencing Harmful Algae Blooms in a Rural Headwater Lake in Cumberland County, Nova Scotia, Canada
Baillie Holmes1, Rob Jamieson1, Joshua Kurek2, Ian Spooner3, Richard Scott1, Lindsay Johnston1, Meggie Letman1, and Jenny Hayward1
1Centre for Water Resources Studies, Dalhousie University, Halifax, Nova Scotia; 2Geography and Environment, Mount Allison University, Sackville, New Brunswick; 3Earth and Environmental Science, Acadia University, Wolfville, Nova Scotia

Eutrophication and algae production are an important lake management issue in rural Nova Scotia. In the past decade, there have been increasing instances of harmful algae bloom events in locations previously unaffected. Mattatall Lake in Cumberland County underwent three major cyanobacteria bloom events in 2014, 2015, and 2016. Research beginning in 2017 focused on quantitatively characterizing phosphorus sources within the Mattatall Lake watershed through water quality monitoring and watershed modelling analysis (using an adaptation of the Nova Scotia Phosphorus Loading Model). Water quality results from the 2017 sampling program indicated that the lake was oligo-mesotrophic. Modelling demonstrated that external phosphorus loads have not increased significantly since 1985. These inconclusive results, not unique to Mattatall Lake, signaled the need for a holistic approach that considers climate, internal, and external influences on lake trophic state. A multiproxy paleolimnological assessment, in combination with hindcasted modeling of lake thermal regime, is being applied. This will aid in further understanding the complex interactions of several variables through time to identify drivers of algae bloom events at enigmatic lakes like Mattatall Lake. Parallel analyses on a lake with similar depth, geology, and catchment landcover with no history of algae blooms will provide reference conditions for this study.

9:15 Diatom and Chironomid Assemblage Shifts Over Several Centuries and Their Relation to Recent Cyanobacterial Blooms in Callander Bay, Lake Nipissing, Ontario
Elizabeth Favot1, Kathleen Rühland1, Andrew Paterson2, and John Smol1
1Queen’s University, Kingston, Ontario, Canada; 2Ontario Ministry of the Environment, Conservation and Parks, Dorset, Ontario, Canada

Callander Bay, Lake Nipissing (Ontario, Canada) has reported increased occurrences of cyanobacterial blooms since 2000. However, monitoring data and previously published diatom-inferred total phosphorus reconstructions indicate that nutrients have not changed in Callander Bay over the past four decades. To examine potential environmental triggers for recent blooms, we use sedimentary diatoms, chironomids, and chlorophyll a from a 210Pb-dated sediment core to track long-term trends in water quality and enable comparisons to regional climate data. Prior to ~1900, biological proxies undergo pronounced changes characterized by a shift in dominance in diatom assemblages from Aulacoseira spp. to Fragilaria mesolepta, and in chironomid assemblages from Procladius spp. to Chironomus spp. Since ~1990, increases in the relative abundances of small-celled, planktonic diatoms (Lindavia comensis, Discostella stelligera, Cyclostephanos tholiformis), together with increases in colonial chrysophyte scales, likely indicate enhanced thermal stability in the bay. Pre-~1900 shifts in chironomid assemblages to Chironomus spp. dominance and the appearance of Endochironomus spp. around 1960 might indicate lower hypolimnetic oxygen in recent decades. We hypothesize that longer and stronger periods of thermal stratification, together with the development of anoxia in bottom waters, could release phosphorus and ferrous iron from the sediments. Collectively, these changes would be advantageous to cyanobacteria and fuel algal growth. Increasing primary production (inferred from sedimentary chlorophyll a) since ~1860 is temporally consistent with the onset of cyanobacterial blooms. Our weight-of-evidence approach suggests that recent algal blooms in Callander Bay are associated with regional climate warming, as they occur during some of the warmest air temperatures on record.

9:35 Algal and Cyanobacterial Productivity in Central Florida Lakes: Using Near-Infrared Reflectance Spectroscopy (NIRS) Models to Document Historical Patterns
Melanie A. Riedinger-Whitmore, Daniel L. Franklin, and Thomas J. Whitmore

Department of Biological Sciences, University of South Florida St. Petersburg, St. Petersburg, Florida

Cyanobacteria are an important lake management concern in central Florida and can cause significant lake impairment. Historical records of algal and cyanobacterial productivity are lacking for many Florida lakes that are prone to cyanobacterial blooms, making it difficult for lake managers to examine how past water quality or watershed changes contributed to this impairment. Paleolimnological methods can be used to document historical trends in productivity for lakes that lack long-term water quality data, and to define baseline conditions needed to establish TMDLs and restoration targets. We are developing near-infrared spectroscopy (NIRS) calibration models for algal and cyanobacterial pigments that can be used to track historical changes in productivity through analysis of lake-sediment cores. NIRS is a rapid, non-destructive, and cost-effective approach that has the potential for broad application in paleolimnology and lake management.

Surface sediment samples from ~65 Florida lakes, ranging from oligotrophic to hypereutrophic conditions, were used to develop NIRS pigment-calibration models. Freeze-dried sediment samples were sieved and homogenized, and NIRS spectral data (400–2500 nm) were obtained using a Metrohm NIRS XDS Rapid Content Analyzer. Sediment pigment concentrations were measured using UV-Vis spectroscopy. Initial calibration models for chlorophyll a (r2 = 0.82), total carotenoids (r2 = 0.82), and oscillaxanthin (r2 = 0.77) were applied to sediment cores collected from lakes in the Kissimmee Chain of Lakes, the headwaters for the Kissimmee River-Lake Okeechobee-Everglades system. We discuss model performance, model refinement, and additional calibration models under development to address lake-management issues.

 

D5: Aquatic Invasive Species II – Survey and Mapping

Moderator: Chris Doyle
SOLitude Lake Management, Washington, New Jersey

8:35 Early Detection of Aquatic Invasive Species in the Finger Lakes Region
Kathryn Des Jardin, Hilary R. Mosher, and Lisa B. Cleckner

Finger Lakes Institute at Hobart & William Smith Colleges, Geneva, New York

Hydrilla (Hydrilla verticillata) is notorious for being one of the most difficult to control aquatic invasive species (AIS) in the United States. It grows quickly, forming dense mats of vegetation that displace native plants and disrupt aquatic communities. It impedes navigation, disrupts water flow, and decreases dissolved oxygen, which harms fish populations.

Hydrilla is on the move in New York’s Great Lakes basin. In the Finger Lakes region alone, populations have been reported and managed in Broome, Cayuga, Monroe, Tioga, and Tompkins counties within the past eight years. It is vital that Hydrilla populations are identified early due to their detrimental effects on the environment and local economy. Not only is Hydrilla expensive to control, recreational swimming, boating, and fishing would be seriously inhibited by Hydrilla invasions. These activities are of particular importance to the Finger Lakes region.

The Finger Lakes Institute (FLI) at Hobart and William Smith Colleges (HWS) was awarded an USEPA Great Lakes Restoration Initiative grant in 2017 to perform early detection surveys targeting Hydrilla. Point-intercept rake toss surveys, adapted from the method developed by the Army Corps of Engineers (Madsen 1999), have been conducted around Cayuga Lake and nearby waterbodies. Several invasive species have been observed during the surveys, including Eurasian watermilfoil (Myriophyllum spicatum), starry stonewort (Nitellopsis obtusa), brittle naiad (Najas minor), curly-leaved pondweed (Potamogeton crispus), and Hydrilla. Such early detection efforts are essential for preventing the devastating effects caused by the establishment of invasive species.

8:55 A Guide to Managing Water Chestnut and Surveying for High Priority Invasives Across the Finger Lakes Region of New York State
Hilary Mosher, Kathryn Des Jardin, and Lisa B. Cleckner

Finger Lakes Institute at Hobart and William Smith Colleges, Geneva, New York

Water chestnut (Trapa natans) is a highly prolific aquatic invasive species known to impair waterways in New York State. The plant can overtake a waterbody within a few years due to its rapid growth whereby 1 ac may yield 100 ac the following year.

The Finger Lakes Institute (FLI) at Hobart and William Smith Colleges (HWS) and Finger Lakes Partnership for Regional Invasive Species Management (Finger Lakes PRISM) began managing water chestnut in the Finger Lakes starting in 2014. In 2016, FLI was awarded an USEPA Great Lakes Restoration Initiative control grant to manage 12 sites selected due to their ecological significance as an Area of Concern (AOC), Important Bird Area (IBA), or a Significant Community.

During this project period, over 16,600 acres of waterways were surveyed for high priority invasives and satellite populations of water chestnut. Sites were surveyed within 1 mi of a known infestation using the rake toss method (Madsen 1999) to determine density of and total number of plant species present. Diversity, average total density, and frequency of invasive species were calculated.

Management occurred across 2,500 acres where 71 tons of biomass were removed via handpulls. An estimated 1,932.5 tons were harvested through partner AIS programs. Outreach resulted in 1,199 students; 1,700 homeowners; and 144,650 community members engaged in prevention through workshops, training, and tabling events; over 2,270 volunteer hours; and an adopt-a-shoreline model of surveillance.

While significant population reductions occurred across sites, continued monitoring and management is warranted to ensure long-term successful management.

9:15 Monitoring Submersed Aquatic Plant Communities on a Large, Canadian Lake: Tracking the Spread of Starry Stonewort (Nitellopsis Obtusa)
Brian Ginn

Lake Simcoe Region Conservation Authority, Newmarket, Ontario, Canada

Lake-wide (200+ site) aquatic plant surveys have been carried out at five-year intervals (2008, 2013, 2018) on Lake Simcoe (Ontario, Canada), complemented by an annual, rapid assessment at 50 sites using the Point Intercept Rake Toss Relative Abundance Method (PIRTRAM). PIRTRAM is used on lakes in Wisconsin, Upstate New York, and other areas to monitor changes to aquatic plant communities and track the spread of invasive species. As these areas have similar floristic communities to Lake Simcoe, we were interested in the applicability of this method on the largest (722 km2) inland lake in south-central Ontario.

Our large surveys verified anecdotal reports of a high plant biomass in the lake, particularly in the relatively shallow, nutrient-rich, Cook’s Bay. A total of 21 species of submersed macrophytes were recorded by these surveys. Plant biomass has increased since early studies in the 1980s, mainly due to increasing water clarity and habitat space, but further increases were recorded due to relatively warmer summer temperatures. In 2008 and 2013, invasive Eurasian watermilfoil (Myriophyllum spicatum) was the dominant shallow water (1–5 m depth) plant species but declined in 2018 due to the expansion another invader, starry stonewort (Nitellopsis obtusa), first recorded in Lake Simcoe in 2009. Results of the PIRTRAM method were consistent with the larger studies, although determining biomass was not possible. Floristic Quality Index (FQI) values have increased lake-wide (18.5 in 2008 to 22.7 in 2016) but show no trend in Cook’s Bay (18.5 in 2008, 19.6 in 2016).

9:35 Utilizing Bio-Acoustic and Point Intercept Submersed Aquatic Plant Mapping Techniques to Delineate Hydrilla (Hydrilla verticillata) in a Large New York Reservoir
Chris J. Doyle

SOLitude Lake Management, Washington, New Jersey

In 2015, hydrilla was documented in the New Croton Reservoir, a 2,300 surface acre New York City drinking water supply. Due to limited funds, the entire littoral zone could not be mapped to delineate the extent of the hydrilla infestation. In 2016, a three-phase approach was employed to make the most efficient use of available funds to delineate the hydrilla. Phase 1 consisted of Bio-acoustic mapping of the littoral zone and overall submersed aquatic plant (SAV) bio-volume. Using the results of Phase 1, we identified SAV “hotspots”, to conduct targeted location point intercept mapping efforts. Using the results of the Phase 2 mapping, we determined five suitable hydrilla tuber monitoring locations to track hydrilla density over time. With increased funding in 2017 and 2018, we were able to conduct point intercept SAV surveys throughout the entire littoral zone. Combining the 2016 Bio-acoustic bathymetry data with the 2018 point intercept data, we were able to determine the extent of hydrilla in the littoral zone for a future comprehensive hydrilla control program.

 

D6: Lake Restoration III

Moderator: Perry Thomas
Kentucky Division of Water, Frankfort, Kentucky

8:35 Nutrient Limitation of Plankton Communities in Lakes Across Northeastern North America
Courtney R. Wigdahl-Perry1, Heather L. Wander2, Emily Carter3, Adrienne Tracy3, Taro Katayama3, Sabrina Volponi4, Kiyoko Yokota5, Shelley Arnott6, Holly Ewing7, Beth Norman8, Mindy A. Morales9, Clayton J. Williams9, Nicole Ward10, Jennifer A. Brentrup10, Kristen T. Holeck11, Denise A. Bruesewitz3, and David C. Richardson2
1State University of New York at Fredonia, Fredonia, New York; 2State University of New York at New Paltz, New Paltz, New York; 3Colby College, Environmental Studies Program, Waterville, Maine; 4Bridgewater College, Bridgewater, Virginia; 5State University of New York at Oneonta, Oneonta, New York; 6Queen’s University, Kingston, Ontario, Canada; 7Bates College, Lewiston, Maine; 8Lacawac Sanctuary, Lake Ariel, Pennsylvania; 9University of Vermont, Burlington, Vermont; 10Dartmouth College, Virginia Tech, Lake Sunapee Protective Association, Hanover, New Hampshire; 11Cornell University, Ithaca, New York

Nutrient management efforts often focus on phosphorus limitation; however, nitrogen may also play an important role in controlling plankton communities in lake ecosystems. In order to understand regional patterns of nutrient controls on plankton growth, we performed nutrient limitation assays at 27 lakes across northeastern North America. These 27 lakes spanned a variety of gradients of chemistry, land use, and productivity. Lake water from each site was amended with inorganic and organic nutrient additions and incubated in situ for one week: control (no additions), phosphorus (P) only, inorganic nitrogen (nitrate/ammonium, IN), organic nitrogen (glycine, ON), and combinations of those treatments (IN +P, ON + P, IN + ON, IN + ON + P). After one week, samples were collected from each bag to examine total algae growth (chlorophyll a) and bacteria growth (cell counts). Colimitation (including serial limitation) was found in most of the lakes (74%), with P limitation and no limitation also observed. The type of nitrogen was important in responses for about half the lakes, with differences in productivity among organic versus inorganic additions. These results indicate the importance of understanding site-to-site variation in nutrient limitation patterns, in order to make effective management decisions at individual lakes.

8:55 Social-Psychological Determinants of Farmer Intention to Adopt Nutrient Best Management Practices: Implications for Resilient Adaptation to Climate Change in the Lake Champlain Basin
Elizabeth Doran1, Asim Zia1,2, Stephanie Hurley3, Yushiou Tsai2, Christopher Koliba1,2, Carol Adair1,4, Rachel Schattman5,6, V. Ernesto Méndez3, Donna M. Rizzo1,7
1Vermont Experimental Program to Stimulate Competitive Research, University of Vermont, Burlington, Vermont; 2Department of Community Development and Applied Economics, University of Vermont, Burlington, Vermont; 3Department of Plant and Soil Science, University of Vermont, Burlington, Vermont; 4Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, Vermont; 5USDA Northeast Climate Hub, USDA Forest Service; 6Extension, University of Vermont, Burlington, Vermont; 7Department of Civil and Environmental Engineering, University of Vermont, Burlington, Vermont

Adaptation to climate change and increased watershed resilience to harmful algal blooms and extreme events requires widespread use of Nutrient Best Management Practices (NBMPs) by farms of all sizes. To better understand farmers’ decisions to adopt NBMPs, we test the social-psychological theory of planned behavior to determine the relative influence of attitudes, perceived social norms, and perceived behavioral control on adoption of nine NBMPs. A survey instrument was designed by the research team and implemented by USDA-NASS (US Department of Agriculture-National Agricultural Statistics Service) in 2013, and replicated in 2016, on a stratified sample of 129 farmers (including panel data on 56 farmers) in the Missisquoi and Lamoille watersheds of the Lake Champlain Basin in Vermont, United States. We developed nine weighted structural equation models to test endogenous (socio-psychological) and exogenous (policy, economic and demographic) predictors of farmer intention to adopt NBMPs. We found that perceived behavioral control has the largest effect size and strongest statistical significance on the NBMP adoption behaviors. Perceived social norms and farmer attitudes were also significant for a subset of NBMPs. Among the exogenous variables, we found that large farm size, college education and conservation easements all had a positive influence on NBMP adoption behaviors. The evidence from this study suggests that for widespread adoption of NBMPs, environmental managers, policy makers, and program developers should be attentive to farmers’ perceived behavioral control, and support the design and execution of outreach and technical assistance programs that build on these and other drivers of farmers’ decision making.

9:15 Recommended Changes to Biosolids Application to Reduce Phosphorus Loading to Surface Waters in Florida
Dean Dobberfuhl, John Hendrickson, and Erich Marzolf

St. Johns River Water Management District, Palatka, Florida

The upper St. Johns River (USJR) is an ecosystem of restored herbaceous marsh and run-of-the-river lakes. The SJRWMD owns and manages over 166,000 acres, striving to restore wetland functions. Despite restoration progress, many of the headwater lakes and streams exhibit significant increasing phosphorus trends and increasing incidences of harmful cyanobacterial blooms, an ominous manifestation for this potable water supply. This upward phosphorus trend is coincident with an increase in the application of wastewater biosolids on pastures in the watersheds. Phosphorus concentrations are significantly correlated with cumulative biosolid phosphorus application. Application in the USJR’s watershed intensified following prohibition in the adjacent Okeechobee watershed. Current regulations base biosolids application on crop nitrogen requirements, which is problematic for a low N:P product. The Florida Department of Environmental Protection recently convened an advisory committee to evaluate the regulations for biosolids use. The committee recommended: establishing the rate of biosolids application based on site specifics (soil adsorption capacity, water table, hydrogeology, site use, distance to surface water; evaluating the percentage of water extractable phosphorus in all biosolids; establishing criteria for low, medium and high-risk sites that guide application practices; increasing the site inspection rate; developing site specific groundwater and/or surface water monitoring protocols to detect nutrient migration; developing and conduct biosolid and nutrient management research on nutrient run-off through surface and groundwater flow with various application rates, biosolids types and different geologic conditions; promoting innovative technology pilot projects for biosolids processing that could provide a wider range of beneficial end products.

9:35 Aquatic Effects Monitoring for the Snap Lake Mine
Colleen Prather1, Jonathan Love2, and Kelly Hille2
1De Beers Canada, Calgary, Alberta; 2Golder Associates, Calgary, Alberta

An Aquatic Effects Monitoring Program (AEMP) is a multidisciplinary aquatic monitoring program, developed in a scientifically defensible way to monitor for development related effects and to provide the basis for informed mitigations. An AEMP was developed to monitor the effects of the Mine on Snap Lake and to meet the commitment that water quality and fish health will remain acceptable.

The discharge of treated mine effluent from the Mine could result in two possible effects: nutrient enrichment or toxicity. Aquatic monitoring has been conducted annually since 2004 to determine if water quality and fish health remain acceptable, or if mitigations are required.

Effects of mine effluent discharge are evident in water quality and phytoplankton but not zooplankton. Concentrations of total dissolved solids, nutrients, and some metals increased in Snap Lake (2004 to 2016), but since 2017 (when the mine entered care and maintenance), and discharge of effluent has decreased, concentrations of most water quality parameters in the lake have started to decrease. In contrast, phytoplankton biomass has increased above the range of natural variability and remained elevated despite water quality improving. Zooplankton biomass has fluctuated over time but has remained with the range of natural variability.

Although water quality has been altered in Snap Lake, the data suggest a negligible effect of toxicological impairment of the aquatic communities but measurable effects of nutrient enrichment; there is no evidence of adverse effects to the structure and function of the aquatic ecosystem in Snap Lake or in downstream environments.