'Hydrometrics’ is the measurement of water levels and flow -…
Local Catchment Assessments – the next step in characterising our catchments
Marie Archbold describes how the EPA Catchments Unit has led the development of guidance on how assessment of the significant pressures in Areas for Action will be completed. This will help identify any activities causing the significant pressures, and will be an important step in acting to manage these.
Local Catchment Assessments are next step for Ireland in the characterisation process. The initial characterisation process, which has been the focus of the Catchments Unit to date, has identified the water bodies that are At Risk of not meeting their water quality objectives, what the impacts are, and what the pressures are at the pressure sector level (e.g. forestry or agriculture). In many of these water bodies, further characterisation is now required to figure out precisely what activities are causing the problems for each individual water body (e.g. a forest roadway or a leaking slurry tank, etc) and how best to get them addressed. Local catchment assessments are how this further characterisation will be carried out.
Guidance on how to carry out Local Catchment Assessments (LCA) has been developed by a Working Group chaired by the EPA and was completed in June 2018. In total twenty-five working group members representing Local Authorities and Public Agencies worked together to develop the five volumes of content for the Guidance. The purpose of the Guidance is to act as a reference manual for organisations involved in undertaking Local Catchment assessments.
What are Local Catchment Assessments?
LCAs are an essential tool in helping us to target our resources, and select and implement the right measure in the right place. The assessment process has been designed to help us answer the following questions about our At Risk water bodies:
- What exactly is causing the unsatisfactory situation, for example, is it nitrogen, phosphorus, ammonium, sediment, or a combination causing the impact?
- Where, when and how exactly are the issues arising?
- What is the particular activity responsible for those impacts?
- How do we solve the problems?
- What strategies and measures are available?
- If the above is still not clear, what further assessment and specialist input is required?
What will Local Catchment Assessments involve?
Different water bodies may require different approaches but overall the structure of LCAs will consist of:
- Undertaking a desk study as the starting point;
- Undertaking catchment walks, if needed;
- Collecting, assessing and recording relevant information and data collected during the catchment walk;
- Concluding on the specific activities causing the impacts;
- Evaluating and proposing possible mitigation options;
- Undertaking or referring the mitigation actions to other public bodies.
What is a Catchment Walk?
A catchment walk is the ’boots on the ground’ component of the Local Catchment Assessment where assessors will walk along, or in, rivers and beside lakes, using ‘basic’, common-sense interdisciplinary science and techniques, to help refine the exact location and nature of the problem activities, and the appropriate mitigation options to help fix them.
The interdisciplinary science collected during the catchment walks will include the following:
- Visual biological indicators, e.g. macroalgae;
- Instream field data such as conductivity, dissolved oxygen, pH, temperature;
- Noting direct pathways, e.g. pipes, cattle access points;
- Noting hydromorphological impacts, e.g. recent drainage, new excavations;
- Noting invasive species, e.g. Himalayan balsam, Japanese knotweed;
- Noting ‘pathway’ indicators, e.g. rushes, rock outcrops;
- Evaluating pathway interceptors, e.g. hedges, riparian zones.
By integrating this data, a clear story can be developed outlining how the catchment areas to water body functions, using the Source-Pathway-Receptor linkages. This catchment story helps pin point the significant pressure activities and target the right measure in the right place.
What does the Local Catchment Assessment Guidance cover?
The Guidance has been written to provide background information for the LCAs. It consists of five volumes and a brief overview of each volume is as follows:
Vol 1: Background, Process and Implementation
This Volume provides an overview of general catchment pressures, indicators and possible mitigation options and outlines what a LCA is and the various components involved in a LCA.
Volume 2: Pressures and Catchment Walks
Volume 2 provides a comprehensive overview of what to look for, or expect, when walking the catchment in relation to each significant pressure type. The significant pressures covered include Agriculture, Hydromorphology, Urban Wastewater Pressures, Diffuse and Small Point Urban Pressures, Forestry Pressures, Peatland Activities, Extractive Industry – Quarries, Mines Industrial Discharge Pressures and Invasive Species.
Volume 3: Observed Indicator Features and Catchments Walks
Volume 3 provides an overview of visual indicators for land drains, vegetation of natural drainage, biodiversity and karst landscape features, and guidance on how risk of water quality impact to groundwater can be screened using a simplified method for estimating zones of contributions of groundwater to natural springs and pumping wells.
Volume 4: Measured Indicator Parameters and Catchment Walks
Volume 4 provides an overview of field methods for the measurement of streamflow and water quality parameters that are indicative of specific environmental pressures. Parameters considered include measurement of streamflow and spring discharges, water temperature, dissolved oxygen, pH, specific electrical conductivity, turbidity, sediment, nutrients and biological indicators. It also outlines the equipment that can be used during the walks, and how monitoring and measurements are carried out.
The biological indicators section introduces a new biological assessment tool called the Rapid Assessment designed to enable the assessor to confirm if a location along a river is clearly impacted or unimpacted. The approach enables the assessor to validate the level of impact quickly. Following a kick sample and rapid inspection (5-10 minutes duration expected), well documented deviations of biota for some common water quality issues prevalent in Irish rivers can be established (i.e. organic and nutrient enrichment, acidification or chemical pollution). The survey is intended to be undertaken in conjunction with catchment walks when recording other field observations and assessing relevant supporting physical and chemical criteria. As it utilises phototrophic indicators, the rapid assessment has most value during summer, when algae are often expected to be most prolific.
Volume 5: Catchment Walk Case Studies
This volume is intended to provide articles on relevant case studies and new supporting information for LCAs. This volume will evolve over time with new articles and documents circulated to add as they become available.
Future updates of the Guidance are anticipated to capture the knowledge and experience gained from undertaking the LCAs. Please keep this in mind and contact us at firstname.lastname@example.org with any suggestions for future iterations.