Rapid Environmental Assessment
of a Drainage Canal System to
Identify Bio-reference Sites for
Wetland Permitting
Abstract
With time and budgetary hindrances facing ecological permitting, the sampling of baseline water quality information depends on Rapid Environmental Assessments (REAs). The researchers investigated the significance of adding the data on fish assemblage, physiochemical parameters and freshwater macroinvertebrate, to rapidly analyze a drainage system in South Texas. They converted the data collected into chemical metrics and averages. Furthermore, they identified the sample locations with the highest collection of metric criteria offering high quality water in the region. The researchers applied the REA approach to determine bio-reference areas which provided baseline information for mitigation plans, future comparisons and wetland permitting. They illustrated that the REA approach was useful for drainage canals and that it provided the appropriate information for the US Clean Water Act 401 and 404. Also, the approach is appropriate for the approval of for the Raymondville Drain Outfall Project as well as wetland permitting.
Introduction
Rapid bio-assessment or REA involves evaluating a location during a fixed context and time frame to examine the existing ecological conditions. The objective of this study approach was to determine the least degree of effort needed to achieve reproducible scientifically sound outcomes. In most cases, consultant environmentalists do not receive the same budgetary allocation or time frame to carry out rapid bio-assessments like the academic-objective researchers. Moreover, the US federal and state wetland permitting usually require rapid bio-evaluation to collect baseline data significant for making environmental decisions. This requirement is specifically applicable to environmental scientists involved in mitigation planning and wetland permitting for development objectives in freshwater ecological systems. In essence, REA comprise rapid bio-evaluation protocols for collecting data of established freshwater fish and macroinvertebrate.
However, the objective of REAS is never to serve as a replacement for full ecological assessments which are required in Environmental Impact Statements (EISs) and as such REAs are subject to extensive criticism. Nevertheless, REAs are essential in environmental permitting when faced by time and budget constraints. Contrary to traditional bio-evaluation tools, a common REA entails field sampling of up to five different sites within four days and giving a conclusive report by the fifth day. Thus, REA is a vital approach extensively applied to wetland characterization and monitoring. Researchers use the REAs generated data to identify impaired versus high-quality biological conditions, that is, wetland ecological health. The data is further applied in watercourse and wetland bio-marking, mitigation as well as enhancement. Although the quality of water of drainage canals in South Texas has been a subject of ecological contamination and exposure, researchers rarely study this phenomenon.
The Texas state’s plan to enhance and enlarge the Raymondville Drainage Outfall System in Willacy and Hidalgo counties provided the chance to conduct an REA of the drainage channel system. Also, there is an existing need to study the quality of eater from various drainage systems when they are subject to flood permitting and control. For this studies, the researchers sampled two sections of the Raymondville Drainage Outfall System to evaluate the quality of water, fish as well as benthic macroinvertebrate. They determined the fish and macroinvertebrate metrics and other physiochemical structures to determine assemblages. The goal of the research was to determine the usefulness of this data in evaluating sampling sites for bio-assessment of the quality of water using an REA based on Texas standard and regional criteria. The requirement to include baseline data in the planning findings plus an EIS for the improvements of the Raymondville Dam Project triggered the researchers to conduct this study. The plan aims at enlarging and widening the construction of the dam and using the drainage system to minimize as well as regulate flooding from longstanding floods and protecting an over eighty-three-hectare basin.
Methodology
The researchers conducted the research in march 2011. They sampled ten sites along the canal system in Willacy and Hidalgo counties in southern Texas and analyzed fish assemblages, macroinvertebrates as well as water quality parameters. This drainage system consisted of two district sections that regulate agricultural runoff and floodwaters. The scientists divided the study region into ten sample sites, five in the North Segment and five in the South Segment. During the selection of the sample locations, they consulted the Texas Commission on Environmental Quality (TCEQ) regarding where drainage and land use could result in variation in water quality. Consulting such an authority enhanced the credibility of the research and its subsequent findings. Land use activities within the vicinity of the drainage system included rangeland and agricultural activities. the researchers did find any input from the wastewater effluents in the canals.
The proposed enhancement of the Raymondville Drain Project primarily the enlargement, environmental management and control structures involved an estimated seventy kilometers of the canal while the drainage ends at the lower Laguna Madre of South Texas. The canal exhibited a turbid, continuous blue-green water and a smooth bottom organic and silt substrate. The researchers collected the samples in two days, something that mimicked an REA approach and reduced potential temporal or seasonal variations. They further applied the surface water quality guidelines (TCEQ, 2007)) to collect water samples. They then transported the samples in refrigerated storage and stored them at 40C until the testing time within forty-eight hours. The scientists then measured water quality parameters using an HI 9828 multimeter and a DR 3800 spectrophotometer in the laboratory. They evaluated field parameters such as temperature, salinity, Ph, dissolved oxygen (DO), Total Dissolved Solids (TDS), turbidity and Specific Electrical Conductivity (EC). There were further tests on nitrites, ammonia, phosphorus, and nitrates using TNT plus chemistries and Hach reagents.