Skip to main content

Change your cookie settings

We cannot change your cookie settings at the moment because JavaScript is not running in your browser. To fix this, try:

  1. turning on JavaScript in your browser settings
  2. reloading this page
View cookies

Change your cookie settings

We cannot change your cookie settings at the moment because JavaScript is not running in your browser. To fix this, try:

  1. turning on JavaScript in your browser settings
  2. reloading this page
View cookies
  1. Home
  2. Search
  3. Historic GQA Headline Indicators of Water Courses - Nutrients - phosphate GQA grades 2010 (Wales)

Historic GQA Headline Indicators of Water Courses - Nutrients - phosphate GQA grades 2010 (Wales)

Summary

This record is for Approval for Access product AfA163.4 'Historic GQA Headline Indicators of Water Courses - Nutrients - phosphate GQA grades 2010 (Wales)'. The General Quality Assessment Headline Indicator scheme (GQAHI) was the Environment Agency's national method for creating a water quality indicator based on rivers and canals in England. This was a reduced network compared to the original GQA network used in England from 1990 to 2006. The Nutrients GQAHI scheme had over 3000 sampling sites which provide information for approximately 22500 km of watercourses. In Wales we maintained the full GQA network until 2010 based on 800 sampling sites which provided information for approximately 4700km. The GQAHI/GQA scheme was designed to provide an accurate and consistent assessment of the state of water quality and how it changes over time. The Nutrients GQA described quality in terms of two nutrients: nitrates (mg NO3 /l) and phosphates (mg P/l) and graded from 1 to 6. Grades were allocated for both phosphate and nitrate; they were not combined into a single nutrients grade. There were no set 'good' or 'bad' concentrations for nutrients in rivers in the way that we describe chemical and biological quality. Rivers in different parts of the country have naturally different concentrations of nutrients. ‘Very low’ nutrient concentrations, for example, are not necessarily good or bad; the classifications merely stated that concentrations in this river were very low relative to other rivers. Classification for phosphate: Grade limit (mgP/l) Average Description <0.02 Very low >0.02 to 0.06 Low >0.06 to 0.1 Moderate >0.1 to 0.2 High >0.2 to 1.0 Very high >1.0 Excessively high Classification for nitrate Grade limit (mg NO3/l) Average Description <5 Very low >5 to 10 Low >10 to 20 Moderately low >20 to30 Moderate >30 to 40 High >40 Very high 2009 is the final year of the scheme.

Use limitation statement

There are no public access constraints to this data. Use of this data is subject to the licence identified.

Attribution statement

© Environment Agency copyright and/or database right 2019. All rights reserved.

Technical information

Update frequency

notPlanned

Lineage

The Nutrients GQAHI described quality in terms of nutrients specifically Phosphate and Nitrates. At each sample points twelve water column samples were collected per annum and each assessment was based on a three year period. Data is represented as river stretches and stored in an zipped access database in four tables on the O drive (Environment Agency's shared drive).

Spatial information

Geographic extent

  • Latitude from: 49.943 to 55.816
  • Longitude from: -6.236 to 2.072
Metadata information

Language

English

Metadata identifier

64b2c39e-d465-11e4-87df-f0def148f590


Published by

Environment Agency

Contact publisher

Defra Data Services Forum

Dataset reference dates

Creation date

01 January 2010

Revision date

N/A

Publication date

N/A

Period

  • From: 01 January 1990
  • To: 31 December 2010

Search

Data and Supporting Information
Data services and download by area of interestLinkAction
Full downloads and supporting documentationFormatAction
Historic_GQA_Headline_Indicators_of_Water_Courses_-_Nutrients_-_phosphate_GQA_grades_2010_(Wales).zipZIPDownload