Idaho Snake- Payette Rivers USDA Water Quality Hydrologic Unit Project

What is the Project About?
The Idaho Snake-Payette Water Quality Hydrologic Unit Project is one of 74 projects funded nationally by USDA. The purpose of these 5-year, federally funded projects is to accelerate the transfer of technology necessary to protect ground and surface water quality while maintaining farm profitability. This project has three phases: (1) determination of groundwater problems in the study area, (2) development of best management practices (BMPs) to deal with observed problems, and (3) implementation of developed BMPs on farms in the study area.

Water quality is an environmental issue that will dominate federal and state legislation in the 1990s. In fact, water quality is a presidential initiative! Because of this there is much at stake with these projects. These projects may be the last chance agriculture has to demonstrate that voluntary best management practices (BMPs) developed to protect water quality can and will work. If these projects are deemed a success, increased regulatory activity may not follow.

Description of Project Area
The Idaho Snake-Payette Rivers Hydrologic Unit Water Quality Project comprises over 840,000 acres in Canyon, Gem, Payette and Washington counties. Within this project are over 3,400 farms covering more than 500,000 acres. Virtually all of the highly productive farmland is irrigated. Agriculture within the study area is very diverse as over 40 different crops are grown. Major crops include: alfalfa (76,800 acres) barley (25,100 acres), beans (12,100 acres), corn (20,800 acres), hops (2,600 acres), oats (9,800 acres), onions (7,700 acres), orchards (12,090 acres), peppermint (11,000 acres), potatoes (5,000 acres), seed crops (8,800 acres), spearmint (2,000 acres), sugarbeets (39,100 acres) and wheat (52,400 acres).

The Problem
Groundwater monitoring surveys have shown that agrichemicals are contaminating many aquifers in Idaho. The Idaho Division of Environmental Quality has identified the Payette and Boise River aquifers in southwestern Idaho as particularly vulnerable aquifers. These aquifers are found in this hydrologic unit study area. This is a major concern since groundwater is the source of drinking water for over 90 percent of Idahoans.

An extensive amount of baseline groundwater data collected in the study area has shown groundwater contamination by nitrates and Dacthal (a herbicide). Intensive and extensive agrichemical use occurs in the study area. Average nitrogen application is 145 lb/acre. Nitrogen use efficiency by crops in the study area averages 50 percent; however, nitrogen use efficiency is less than 20 percent under poor management conditions. In addition to nitrogen, over 100 agrichemicals are used in the study area.

Shallow sensitive water tables exist within the study area. For marketing and storage reasons, surface irrigation is the preferred method for irrigating most crops in the study area; however, furrow irrigation efficiency average 35 percent and has been measured as low as 20 percent on some farms. Irrigation sets are often long runs and extended duration, which results in deep percolation of soluble materials. This results in a serious loss of water and movement of chemicals under cropping systems where large amounts of water and agrichemicals are applied.

This project site was selected because agricultural cropping systems and hydrological characteristics make groundwater in southwestern Idaho particularly vulnerable. If voluntary BMPs developed and implemented here work, they can be applied in other irrigated parts of the Northwest.

Project Objectives/Goals
The objectives of this project include:

1. Determine the extent of nonpoint source pollution of groundwater from pesticides and nutrients.
2. Determine the nutrient and pesticide contribution of crops such as onions, potatoes, mint, corn, etc., produced under surface irrigation vs. crops such as cereals, alfalfa, pastures, etc.
3. Develop and implement best management practices (BMPs) that will reduce to acceptable levels the loss of nutrients and pesticides from the root zone into critical groundwater aquifers.
4. Develop an economic evaluation of BMP effectiveness.
5. Develop an information and education plan evolving from information used and gathered from this project.

1. Improvement in water quality, particularly groundwater quality.
2. Identification of areas within the study unit that have the greatest groundwater quality problems.
3. Identification of the crops most responsible for degradation of groundwater quality; alternate management systems developed to produce identified high-risk crops.
4. Improved nutrient, pesticide and water management.
5. Grower acceptance of developed and introduced BMPs within the project area.
6. Identification of additional research needs to meet water quality goals.
7. Improvement of farm profitability.
8. Development of BMP programs with water quality goals that can be utilized by private consultants within the region.
9. Establishment of good coordinated working relationships among all agencies working on this project.

Lead Agencies
Three lead agencies are principally responsible for this project: Soil Conservation Service (SCS), University of Idaho Cooperative Extension System (CES) and Agricultural Stabilization and Conservation Service (ASCS).

Other Major Participants:
Payette Soil Conservation District
Canyon Soil Conservation District
Gem Soil Conservation District
Weiser River Soil Conservation District
Idaho Department of Agriculture
Idaho Department of Water Resources
Idaho Division of Environmental Quality
Idaho Soil Conservation Commission
Local Irrigation Districts
University of Idaho Agricultural Experiment Station
West Cassia Soil and Water Conservation District

This brochure, WQ-4, was prepared by R. L. Mahler. Mahler is Water Quality Coordinator, Soil Science Division, University of Idaho, Moscow, Idaho 83844-2339. Project office located at: 1630 Third Ave. S., Payette, ID.

3M, 8-91

Comments to webmistress: karenl@uidaho.edu

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College of Agricultural and Life Sciences, University of Idaho.
All rights reserved.

Revised: January 3, 2003

URL: http://www.uidaho.edu/wq/wqbr/wqbr4.html