5 Oct 2023

Review of Riparian Models for Assessing Ecological Impacts and Benefits

BACKGROUND: Riparian zones are key transitional ecosystems between upland and aquatic zones, and these systems are often degraded due to both land use change and stream processes (e.g., deforestation and water impoundments and/or diversions). These important ecosystems require restoration because of the many benefits they provide ranging from providing habitat for diverse species to promoting water quality. Restoration practitioners, regulators, and researchers require riparian assessment methods and models to efficiently guide mitigation and restoration planning. This technical note (TN) compiles a subset of existing riparian tools and evaluates them relative to model objectives, modeling approach, and input variables. Findings are synthesized into a gap analysis of these models to inform future riparian model development and improve riparian assessment.

5 Oct 2023

Unmanned Aircraft Systems and Tracer Dyes Potential for Monitoring Herbicide Spray Distribution

Purpose: Chemical control of nuisance aquatic vegetation has long been the most widely utilized management tool due to its high level of efficacy, limited environmental impacts, and relatively low cost. However, unprecise application of herbicides can lead to uncontrolled invasive plants and unintended management costs. Therefore, precision herbicide delivery techniques are being developed to improve invasive plant control and minimize impacts to non-target plants. These technological advancements have the potential to enhance aquatic ecosystem protection from invasive species while reducing associated management costs. Despite the benefits of using registered herbicides for aquatic plant control in efforts to restore aquatic habitats, their use is often misunderstood and opposed by public stakeholders. This can lead to significant challenges related to chemical control of nuisance aquatic vegetation. Thus, US Army Corps of Engineers (USACE) Districts seek improved methods to monitor and quantify the distribution (i.e., amount of herbicide retained on plant foliage compared to those deposited into the water column) of herbicides applied in aquatic systems. Monitoring herbicide movement in aquatic systems can be tedious and costly using standard analytical methods. However, since the inert fluorescent tracer dye Rhodamine WT (RWT) closely mimics product movement in the aquatic environment it has been used as a cost-effective surrogate for herbicides tracing.

5 Oct 2023

Rapid Algae Flotation Techniques

Abstract: Some harmful algae produce mucilage or extracellular polymeric substances useful for flotation. This study evaluated natural polysaccharides to determine effects on algal flotation with DAF. Food-grade gums (xanthan gum, guar gum, gum arabic, gellan gum, and diutan gum) were tested with cyanobacteria cultures singly and in combination with commercial flocculants (including Tramfloc 222 and Tramfloc 300). Gum arabic alone had no effect when evaluated at concentrations between 10 mg/L and 5,000 mg/L. However, the combination of gum arabic and Tramfloc 300 yielded higher algal flocculation than Tramfloc 300 alone. The combination of xanthan gum (anionic) and guar gum (cationic) did not perform at the level of the combined xanthan gum and Tramfloc 222 in either flocculation or flotation of algae. Tramfloc 222 and xanthan gum; however, yielded effective flocculation seemingly resistant to changes in interfering factors such as turbulence, pH, and temperature. Furthermore, the combination of xanthan gum and Tramfloc 222 provided the most effective flotation and flocculation independent of pH effects. The results suggest that anionic polysaccharides can be used to increase the efficacy of cationic coagulants such as Tramfloc 222.

5 Oct 2023

Beneficial Use of Dredged Material: A Workshop to Explore Engineered Drainage Soils for Stormwater Management

PURPOSE: Beneficial use of dredged material in engineered soils is an alternative to achieve environmental and economic sustainability for waterway operations. Engineered soils can combine navigation and environmental dredging with municipal and commercial waste streams to create a valuable commercial soil product while reducing public operating costs, creating economic opportunity, and creating better soil products for lower cost. The need, opportunities, and challenges to establishing an Illinois Waterway-based commercial soil industry were explored by river, highway, stormwater, environmental resource managers, and industry experts in a workshop in Peoria, IL, on 4–5 September 2019.

29 Sep 2023

A Regional Guidebook for Applying the Hydrogeomorphic Approach to Assessing Wetland Functions of Forested Riverine Wetlands in Alluvial Valleys of the Piedmont Region of the United States

Abstract: The Hydrogeomorphic (HGM) approach is used for developing and applying models for the site-specific assessment of wetland functions. It was initially designed for use in the context of the Clean Water Act Section 404 Regulatory Program permit review process to analyze project alternatives, minimize impacts, assess unavoidable impacts, determine mitigation requirements, and monitor the success of compensatory mitigation. However, a variety of other potential uses have been identified, including the design of wetland restoration projects, projecting ecological outcomes, developing success criteria and performance standards, and adaptive monitoring and management of wetlands. This guidebook provides an overview of the HGM approach including classification and characterization of the principal alluvial riverine wetlands identified in the Piedmont physiography. Eight potential subclasses of Piedmont wetlands, including Headwater, Low- and Mid-gradient Riverine, Floodplain Depression, Footslope Seeps, Flats, Precipitation Depressions, and Fringe wetlands were recognized. However, the occurrence of Flats, Precipitation Depressions, and Fringe wetlands in the Piedmont, are uncommon and not generally associated with alluvial riverine systems which is the subject of this Guidebook. Detailed HGM assessment models and protocols are presented for the five most common Piedmont riverine subclasses: Headwater, Low- and Mid-gradient Riverine, Floodplain Depression, and Footslope Seep. For each wetland subclass, the guidebook presents (a) the rationale used to select the wetland functions considered in the assessment process, (b) the rationale used to select assessment models, and (c) the functional index calibration curves developed from reference wetlands used in the assessment models. The guidebook outlines an assessment protocol for using the model variables and functional indices to assess each wetland subclass. The appendices provide field data collection forms. In addition, an automated spreadsheet model is provided to make calculations.

26 Sep 2023

During Nearshore Event Vegetation Gradation (DUNEVEG): Geospatial Tools for Automating Remote Vegetation Extraction

Abstract: Monitoring and modeling of coastal vegetation and ecosystems are major challenges, especially when considering environmental response to hazards, disturbances, and management activities. Remote sensing applications can provide alternatives and complementary approaches to the often costly and laborious field-based collection methods traditionally used for coastal ecosystem monitoring. New and improved sensors and data analysis techniques have become available, making remote sensing applications attractive for evaluation and potential use in monitoring coastal vegetation properties and ecosystem conditions and changes. This study involves the extraction of vegetation metrics from airborne lidar and hyperspectral imagery (HSI) collected by the US Army Corps of Engineers (USACE) National Coastal Mapping Program (NCMP) to quantify coastal dune vegetation characteristics. A custom geoprocessing toolbox and associated suite of tools were developed to allow inputs of common NCMP lidar and imagery products to help automate the workflow for extracting prioritized dune vegetation metrics in an efficient and repeatable way. This study advances existing coastal ecosystem knowledge and remote sensing techniques by developing new methodologies to classify, quantify, and estimate critical coastal vegetation metrics which will ultimately improve future estimates and predictions of nearshore dynamics and impacts from disturbance events.

26 Sep 2023

Microseira wollei (M. wollei) Blooms in Freshwater Ecosystems in Lake St. Clair (Michigan, USA)–Impacts and Possible Management Approaches

PURPOSE: The proliferation and shoreline accumulation of the filamentous biphasic cyanobacterium, Microseira wollei (M. wollei) (previously classified as Lyngbya wollei), have become an increasing problem in the Great Lakes, both for aesthetic reasons and its potential to harbor harmful bacteria and pathogens (Vijayavel et al. 2013). Occurrences have been reported and studies have also been conducted in the southeastern US where M. wollei has become a nuisance in recent years and is known to produce toxins (Hudon et al. 2014). Reports of M. wollei proliferations in the eastern US have been identified in the Manitoba lakes (Macbeth 2004), in Lake Erie from Maumee Bay (Bridgeman and Penamon 2010), in Lake St. Clair near Detroit (Vijayavel et al. 2013), and throughout the St Lawrence River (Vis et al. 2008; Lévesque et al. 2012). M. wollei has become a serious nuisance for marinas, public beaches, and lakefront property owners. In addition, M. wollei appears to have the ability to produce a wide range of toxins, but the conditions promoting their production, type, and concentration are poorly known (Hudon et al. 2014). Occurrences of large algal mats matching characteristics of M. wollei have been observed along the northwest shore and nearshore waters of the beach at Lake St. Clair dating back to 2010. To date, a comprehensive study detailing the potential impacts M. wollei has on freshwater ecosystems in the Great Lakes River, particularly Lake St. Clair is lacking. Further, management solutions are not well understood. This technical note (TN) reviews the potential causes of M. wollei blooms and their ecological impacts on aquatic systems and assesses the management options available to eliminate or minimize the impacts of these blooms.

26 Sep 2023

Linking the SEDLZJ Portable Standalone Library to the CMS Coastal Hydrodynamic Model

PURPOSE: This document describes the repackaging and linkage of the Sandia National Laboratories Environmental Fluid Dynamics Sediment Processes Code (SNL-EFDC-SEDZLJ), (Thanh et al. 2008). It was originally incorporated within a modified version of the US Environmental Protection Agency’s (USEPA) EFDC public-domain surface-water flow, sediment transport, and water-quality model developed by John Hamrick (Hamrick 1992) and its linkage to the ERDC-CHL-CMS hydrodynamic model. SNL-EFDC simulates flow and transport of sediment as bedload and suspended load. SNL-EFDC-SEDZLJ improves EFDC with updated sediment kinetics subroutines. Sediment erosion is calculated using data collected with a Sediment Erosion at Depth flume (SEDflume). SEDflume measures erosion rates as a function of shear stress and depth from relatively undisturbed cores taken directly from the sediment bed below the water body of interest. The use of SEDflume data provides more accurate sediment erosion rates that are directly input to the model.

25 Sep 2023

Defining Levels of Effort for Ecological Models

BACKGROUND: While models are useful tools for decision-making in environmental management, the question arises about the level of effort required to develop an effective model for a given application. In some cases, it is unclear whether more analysis would lead to choosing a better course of action. This technical note (TN) examines the role of ecological model complexity in ecosystem management. First, model complexity is examined through the lens of risk informed planning. Second, a framework is presented for categorizing five different levels of effort that range from conceptual models to detailed predictive tools. This framework is proposed to enhance communication and provide consistency in ecological modeling applications. Third, the level of effort framework is applied to a set of models in the Middle Rio Grande River system to demonstrate the framework’s utility and application. Ultimately, this TN seeks to guide planners in determining an appropriate level of effort relative to risks associated with uncertainty and resource availability for a given application.

21 Sep 2023

Field Demonstration of a Peroxide-Based Algaecide for Harmful Algal Bloom Control in Lake Okeechobee

Abstract: Large-scale cyanobacterial harmful algal blooms (cHABs) in Lake Okeechobee, Florida, and connected waterways routinely impair water resources. This study conducted a field demonstration of a peroxide-based algaecide in 2020 in the Pahokee Marina on Lake Okeechobee to evaluate the algaecide’s suitability for near-future operational implementation. Within minutes of treatment, rapid oxidation of cHAB cells occurred in the form of bleaching and cell lysis. On average, levels in the treatment area decreased by 4 hours after treatment (HAT) and remained low out to 24 HAT: chlorophyll decreased 87%, phycocyanin decreased 85%, total microcystin levels decreased from 50 μg L⁻¹ to 4 μg L⁻¹ at 4 HAT and then increased to 11 μg L⁻¹ by 24 HAT, hydrogen peroxide concentrations averaged 6.1 mg L⁻¹ 0.5 HAT and then dropped below detection limits by 24 HAT, and Microcystis spp. cell densities decreased at 4 HAT in all but four sampling sites. However, inflows of cHAB-infested lake water in some portions of the treatment area resulted in lack of control at these sites. Because of their vulnerability to influxes of cHABs from surrounding nontreated waters via water-exchange processes driven by wind-induced surface currents, future applications must therefore consider treatment area size.