In Reply Refer To:
Mail Stop 409

March 30, 2010

Memorandum

Distribution:      GS-W All
 cc:                   GS-D Regional Executives

From:               Matthew C. Larsen
                        Associate Director for Water

Subject:            WRD Policy Numbered Memorandum No. 2010.02
                        Continuous Records Processing of all Water Time Series Data

Because of increasing availability and use of U.S. Geological Survey (USGS) streamgaging, water-quality monitoring, and other time-series hydrologic data in real-time decision making processes, users have requested that data be approved or published much sooner after collection than has been USGS policy in the past.  As a result, all Water Science Centers (WSCs) shall implement Continuous Records Processing (CRP) of all water time-series data by June 30, 2010 with the full understanding that it may take some time for full implementation. Continuous records processing is the collection, analysis, review, and approval of time-series hydrologic data on a continuous (sub-water year) basis. At any given time, the time-series data will be as close to approval as computational methods and hydrologic interpretation will allow. This general definition of CRP is implemented through the following operational timelines:

  1. All real-time water data must be reviewed by a hydrographer and checked for gross instrument errors within 1 day of collection (WRD Policy Memorandum 99.34).
  2. All time-series data collected at Category 1 sites (defined below and in attachment 1) are to be finalized within the National Water Information System (NWIS) within 150 days of collection.
  3. All time-series data collected at Category 2 sites (defined below and in attachment 1) are to be finalized within NWIS within 240 days of collection.
  4. Ultimately, regardless of category, all data need to be approved, finalized, and published (per Water Science Center policy) as part of the Annual Water Data Report by April 1 of the year following the water year of collection.
There are two basic guiding principles implicit in this definition. The first is that CRP must be data driven.  This means that streamflow, groundwater levels, water-quality parameters, or other time-series information are not approved until the analyst and reviewers are satisfied that the data are ready for approval and distribution without caveat. The approval criteria will depend on the individual site and its climatic and hydraulic characteristics, the stability of those characteristics, and the field protocols being used at that site. With this principle as a guide, data need to be reviewed and approved as soon as possible after all the necessary information becomes available. Resources must be allocated and prioritized to facilitate this timely review and approval.

The WSCs are to categorize their sites according to the criteria set up in the Continuous Records Processing Implementation Plan- May 2008 (attachment 1) which was prepared by the Continuous Records Processing Implementation Committee. Because most real-time sites are currently surface-water sites, these categorizations will initially be tracked by the Office of Surface Water with the intention that an official database (NWIS or Station Information Management System (SIMS)) will eventually be used to track the categorization of sites. Category 1 sites are defined as sites for which the data needed to compute records for a period between site visits are in hand at the end of a site visit.  These time-series records should be finalized within 150 days of collection. Category 2 sites are defined as sites for which more data are needed for specific seasonal record computation (such as long term ice effect), streamgages that have unstable controls and longer periods are needed to determine trends, or where data from continuous water-quality analyzers depend upon laboratory results for verification. Category 2 time series records should be finalized within 240 days of collection. Category 3 sites are special cases where a continuous record processing does not currently apply.  These types of sites should be rare and each case may be unique.

The second guiding principle is that CRP cannot degrade the accuracy of the hydrologic information published by the USGS. High standards of accuracy and precision must be maintained in all data collection and analysis procedures. The USGS must provide the best data to the public as soon as possible.

A number of recommended practices are included in the Continuous Records Processing Implementation Plan (attachment 1). WSCs are urged to read the plan and consider adopting those practices that will help meet the goal of full implementation of continuous processing of time series data within the Water Resources Discipline.

Attachment 1 - Continuous Records Processing Implementation Plan – May 2008