SCADA vs. GCD ga

Glen Canyon Dam Adaptive ManagemenTechnical Work Group MeetingFebruary 26, 2002Prepared by:Bill PersonsArizona Game and Fish Department
TO: Technical Work Group members

FROM: Bill Persons, Arizona Game and Fish DepartmentDATE: December 11, 2001RE: Assessment of Glen Canyon Dam Gage and SCADA dataAt the last Technical Workgroup meeting (November 13-14,2001) I was asked to evaluate the the Glen Canyon Dam Gage (USGS 09379910) and the SCADA system and to make a recommTWG as to whether to close down the Dam gage and rely soley on the SCADA system for disccontacted Kirk LaGory, Argonne National Lab, and obtained the SCADA data he used in his aat Glen Canyon Dam and also downloaded Glen Canyon Dam gage data from the USGS web s(http://dg0daztcn.wr.usgs.gov/rt-cgi/gen_stn_pg?station=09379910). 

I compared the two data sets, and found that for some time periods SCADA data were not avaidata values were not uncommon. I contacted Kirk LaGory and he confirmed that the data for 

March 2001 and 9 April 2001 - 15 April 2001 were not available and were not on the website tposted SCADA data. I attempted to contact the website where SCADA data have been posted access the site. Kirk confirmed that it is not uncommon for the SCADA system to not report dreported that the SCADA system gives anomalous reading occasionally.I’ve prepared two graphs of a period with missing SCADA data (March 2001), one showing thdata and one showing the USGS dam gage data, that highlight my concerns with relying on the provide accurate, reliable data. Note that the period of missing data from the SCADA system 

corresponds with a period that shows unusually high releases at the USGS gage. The high discdam gage also appears at the Lees Ferry gage. SCADA system data are not always available, and the system also gives anomalous readings oUSGS system provides reliable, easily accessible, published discharge and stage data. USGS daccessed “real-time” on the internet. Therefore, my recommendation is that the USGS gagof Glen Canyon Dam be maintained.
Note N/A

data “Not available” for4/2001, 3/2001, 7/2000

Note N/Adata “Not available” for4/2001, 3/2001, 7/2000

SCADA web page
Note: This 

SCADA infor

mation is 

believed to be reliable but is not guaranteed to be correct. It is subject to change...

Note: This SCADA infor

mation is 

believed to be reliable but is not guaranteed to be correct. It is subject to change...

SCADA web page (2
Note missing data Note missing data

SCADA data March 20

Date

0

03/23

03/21/200

03/20/2001 03/18/2001 03/16/2001 03/15/2001 03/13/2001 03/12/2001 03/10/2001 03/08/2001 03/07/2001 03/05/2001 03/04/2001 03/02/2001 03/01/2001

SCADA data cfs

22000200001800016000140001200010000

8000600040002000

0
Note complete 

data for March

Note complete data for March

GCD gage data March 2

Date

03

03/23/20

03/21/2001 03/20/2001 03/18/2001 03/16/2001 03/15/2001 03/13/2001 03/12/2001 03/10/2001 03/08/2001 03/07/2001 03/05/2001 03/04/2001 03/02/2001 03/01/2001

Dam gage cfs

22000200001800016000140001200010000

8000600040002000

0
Lees Ferry

gage confirms GCD gage forMarch 2001.

Lees Ferrygage confirms GCD gage forMarch 2001. Lees Ferry gage March 2
Note ease of 

retrieving data.

Note ease of retrieving data.

Example of USGS data quer
Data 

retrieval is awkward with SCADA system

Data retrieval is awkward with SCADA system

Example of SCADA file f
Summary:

SCADA

• Not always available• Unreliable• Occasional anomalous 

reading

• Difficult format to convert 

to usable datafiles

US

• Easily avai• Reliable• Published d

stage data

• Consistent 

conversion 
Example data from USGS web site

Glen Canyon Dam gage and Lees Ferry gage, February 15 –

22, 2002.
GCD Gage and LF Gage

6,0007,0008,0009,000

10,00011,00012,00013,00014,000

0123456

Time

cfs