BOARD01305

• Board Meeting Date: 3/16/2004
• Description: WSP Section - Arkansas River Basin Salinity Study
• Board Meetings - Doc Type: Memo

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STATE OF COLORADO

Colorado Water Conservation Board

Department of Natural Resources
1313 Sherman Street Room 721
Denver, Colorado 80203
Phone: [phone]
FAX [phone]
www.cwcb.state.co.us

MEMORANDUM

Bill Owens
Governor

To: Colorado Water Conservation Board Members

From: Steve Miller Sft-~ ~
Date: March 3, 2004

Russell George
Executive Director

Rod Kuharich
CWCB Director

Re:

Agenda Item 10, March 16-17, 2004, CWeB Meeting. Water Supply Protection-
Arkansas River Basin Salinity Study

Dan McAuliffe
Deputy Director

Introduction

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Dr, Tim Gates, Colorado State University ("CSU"), Department of Civil Engineering, has been invited to give a
presentation to the Board about his ongoing research project in the Lower Arkansas Basin. The project involves
measuring, mapping and modeling irrigation water practices and the resulting impacts on water quality and
groundwater tables, An overview of the project prepared by Dr. Gates is attached,

Discussion

Dr, Gates, as well as CSU Cooperative Extension Service, has been conducting irrigation and drainage related
research in the Lower Arkansas Basin for approximately five years, Dr. Gates recently gave a presentation on this
work at the January 2004 Colorado Water Congress Annual Meeting. Staff thought this subject would be of
interest to the Board and asked Dr, Gates to give a brief presentation on his research to the Board at this meeting,

Water quality issues in the Lower Arkansas, particularly salinity or total dissolved solids ("TDS"), have long been
recognized as a serious and complex problem, Marine derived soils and extensive reuse of irrigation return flows
both concentrate the background river salinity and mobilizes new salt loads into the river. The result is a steady
and dramatic increase in TDS levels in a downstream direction - from less than 1000 ppm at Pueblo to over 3000
ppm at the Colorado. Kansas Stateline. More recently advocates with various agendas have asserted water quality
concerns in opposition to proposed operational changes in the river regime, Much of that rhetoric has been
incorrect and illogical. Dr, Gates' analysis of the physical river-field.groundwater system will provide a scientific
basis from which to quantitatively evaluate the impacts of salinity and potential remedial actions,

The project team put in place by Dr. Gates for this ongoing work is also proposed to be utilized to obtain crop and
evapotranspiration data for the Kansas v, Colorado litigation under the studies discussed at agenda item 11 of this
meeting,

Recommendation

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There is no staff recommendation, this item is informational only, Dr, Gates has reserved time in his presentation
to respond to questions from the Board, The Board might also consider touring the area being studied as part of
its September 2004 meeting in La Junta.