Rotational Management of Wetlands and Croplands in Tulelake Basin

Project Overview

Project Type: Research and Education
Funds awarded in 1994: $0.00
Projected End Date: 12/31/1999
Matching Non-Federal Funds: $39,186.00
ACE Funds: $259,633.00
Region: Western
State: California
Principal Investigator:
Carol Shennan
University of California, Santa Cruz

Annual Reports


Not commodity specific


  • Crop Production: crop rotation, nutrient management
  • Natural Resources/Environment: wetlands, wildlife


    Tulelake is a high mountain valley on the California Oregon border where irrigated agriculture coexists adjacent to the Tulelake National Wildlife Refuge. The refuge is a critical part of the Pacific flyway and with Lower Klamath Refuge supports 1 million migrating waterfowl, annual waterfowl production of 40,000, and habitat for 411 wildlife species. Concerns facing the basin include; degeneration of wetland habitat, hypereutrophication, pesticide use, declining populations of endangered fish and declining crop productivity due to build up of nematodes and other soil pathogens.

    Improved management strategies to sustain agriculture and provide high quality wildlife habitat are needed. One strategy proposed is to flood areas of existing cropland to create new diverse wetlands, and drain areas of existing wetland to create cropland free of soil borne pathogens. In this project we established pilot studies to assess the feasibility of cropland/wetland rotations in terms of crop production, pest control, quality of wildlife habitat created, effects on water quality, and socioeconomic impacts. A major goal was to communicate with different sectors of the local community, Federal/State agencies, researchers, and other organizations active in Klamath Basin issues, and to incorporate different perspectives into this study as it developed.

    During the course of this grant we completed baseline soil and water sampling of all the pilot sites, and initiated wetland/cropland rotational management at each location. Vegetation development, impacts on water quality and seasonal water use were monitored at selected sites. While variation in vegetation development across pilot sites was observed, abundance of desired wetland species was achieved in most sites by the second year of seasonal flooding. Water quality impacts of seasonal wetlands depended upon time of drainage and the degree of subsurface to surface drainage. A GIS based hydrological model is being developed to predict water use and quality impacts of different rotational land use schemes. Preliminary data suggest that newly created permanent marshes can improve surface water quality for much of the season, and significantly reduced nematode populations.

    A digitized base map of the basin was developed in cooperation with the US Bureau of Reclamation office in Klamath Falls. Multiple layers of inherited physical and socioeconomic information together with data collected from the pilot sites have been entered to create a spatial database for the area. This GIS database is being used to develop models to assess the impacts of various management options on economic and environmental aspects of the ecosystem.

    Project objectives:

    • To conduct pilot studies to assess the feasibility of wetland/cropland rotation (flooding of existing cropland to create new wetlands, and drainage of existing wetland to create new farmland) as a long term management option for sustainable coexistence of irrigated agriculture and wetland reserves in the Tulelake basin.

    • To determine the impacts of wetland/agriculture rotations using various management strategies on: water quality, seasonal dynamics of nutrient release/immobilization, pesticide residue movement, crop productivity, development of marshland vegetation and the quality of wildlife habitat created.

    • To compare the ability of managed wetland systems and irrigated cropland to remove or immobilize nutrients and other residues from agricultural drainage water.

    • To test the utility of short term flooding cycles to control soil borne pathogen and nematode populations within irrigated cropland rotations, and determine the extent of use of these temporary wetlands by wildlife.

    • To assess the socioeconomic impacts and policy implications associated with rotational wetland/agriculture management systems.

    • To coordinate this project with other research/planning activities in the Klamath Basin, and facilitate involvement of different community groups, State and Federal Agencies and other organizations in the development of the pilot projects.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.