May 1997
Water that fills the Tule Lake and Lower Klamath NWRs is dependent on climatic conditions and agricultural irrigation return flows. Historically, Lower Klamath wetlands received water during the flooding of the Klamath River. Water would flow through the area known as the Klamath Straits to Lower Klamath Lake. This flow was blocked by the construction of the Southern Pacific railroad embankment in the early 1900s (see Figure 1 (120K)). Since water did not drain efficiently from the Lower Klamath wetlands, the soils built up salts, causing locally alkaline soils.
Quaternary lava flows blocked the Lost River from draining into the Klamath River. That diversion resulted in the flooding of the Tule basin forming the Tule Lake wetlands. There was no surface outflow for these wetlands. However, a significant quantity of water was lost through the southern rim of the lake into the fractured lava beds. The movement of water through the system to the south contributed to the flushing of salts and laid down rich deposits of organic material.
Today Tule Lake receives all of its surface flows from conveyances that are a mixture of Lost River water and irrigation return water (Sorenson and Schwarzbach 1991). The irrigation system is illustrated in Figure 1 (120K). The Lost River Diversion Channel was originally constructed to divert Lost River water to the Klamath River to aid in the draining of Tule Lake. To further stabilize water elevation within the Tule Lake sumps, the Tule Tunnel was constructed (as previously discussed). Direct flow monitoring of water entering the refuges has not occurred, therefore it is not possible to estimate a water budget at this time. Competition for water resources is important in the allocation of water supplies. During periods of sub-normal precipitation, neither agricultural nor wildlife interests are content with current water availability.
Habitat for fish movement is severely restricted by the fact that irrigation systems serve as the primary fish corridors. Habitat effectiveness is reduced both by lack of sufficient water quality and quantity, as well as lack of appropriate structural habitat.
Historically, Tule Lake and Lower Klamath NWRs have been productive aquatic ecosystems. Surface waters were supplied with nutrients during annual flooding of the Lost and Klamath rivers, and became eutrophic. (The term eutrophic simply describes water that is rich in nutrients; a relatively productive condition [Edmondson 1991].) The geologic setting did not provide surface water outlet flows (that would have removed nutrients from the wetlands) for Tule and Lower Klamath lakes. This resulted in the retention of nutrients. In relatively short geological time (hundreds to thousands of years), the build-up of nutrients led to eutrophic condition of the surface waters. Eutrophication is the process by which surface waters become rich in nutrients. Eutrophication occurs over time when there are events that result in additional nutrient input to a lake from its watershed. These events include wildfires, earthquakes, floods, erosion (both wind and water), landslides, and leaching of nutrients from soils. This is known as natural eutrophication. Cultural eutrophication occurs when human activities cause nutrient loading to increase. In many cases, this accelerated nutrient loading is in excess of the capacity of a water body to assimilate the nutrients without a degradation of water quality.
Lakes and wetlands can be eutrophic without a general degradation in water quality. The difference between a "natural" eutrophic condition and a "cultural" eutrophic condition is the system's ability to assimilate the increase in nutrient loading due to human activities. In a culturally eutrophic situation, water quality and other limnological characteristics decline. This decline is due to a change in the ecosystem's balance. For example, the water quality within the refuges generally has been considered poor for the last three decades (Sorenson and Schwarzbach 1991, MacCoy 1994, Bennett 1994, and Keith 1966). Land-use activities over the past 100 years (both on and off Refuge) that have contributed to nutrient loading are: land development; road-building; logging; landscaping; on-site waste disposal; impervious surfacing; water resource management of the Lost River system; and flood-irrigation and other agriculture activities. Both natural and cultural nutrient loading throughout the basin have resulted in the poor water quality conditions that exist upstream of the Tule Lake NWR. Some activities with NWR leased lands, in addition to the irrigation system and on-site waste disposal, are not providing the necessary conditions to improve water quality as it moves through the Refuge, as demonstrated by the data collected by Sorenson and Schwarzbach (1991), MacCoy (1994), and Bennett (1994).
Nitrogen and phosphorus concentrations within return irrigation flows on the Tule Lake NWR were almost 10 times the level that would be considered eutrophic (Bennett 1994). Bennett (1994) also observed concentrations of nitrogen and phosphorus in the Tule Lake sumps to be well in excess of eutrophic thresholds (Cooke et al. 1993). Within the Klamath Basin, algal blooms are commonplace and are part of the normal surface water dynamics. For example, Upper Klamath Lake annually supports massive blue green algae (Aphanizomenon flos-aquae) that use nutrients recycled from rich lake sediments (Johnson et al. 1985). Algal blooms also have occurred at Tule Lake in the past. The density of algae and turbidity (caused by high concentrations of suspended solids) limits the development of emersed and emergent rooted plant growth within the open water areas. This is a highly limiting factor for habitat diversity of the wetlands.
Nutrient availability allows for rapid growth of algae, particularly blue-green algae. At night, dense populations of algae consume oxygen for respiration, and when they die and decay, more oxygen is consumed by the microbial (bacterial and fungal) community. Natural and cultural eutrophication of the wetlands have resulted in low dissolved oxygen conditions. In over-enriched systems, such as Tule Lake, this cycle of oxygen depletion exceeds oxygen replenishment. Dissolved oxygen concentrations as low as zero have been documented by both Bennett (1994), and MacCoy (1994). The low oxygen levels increase environmental stress and reduce habitat for fisheries within the refuges. In addition, the low oxygen concentrations create a zone where biochemical processes can occur that further degrade water quality. Consistently low levels of oxygen were measured in 1991 through 1992 by MacCoy (1994) on the refuges.
High levels of potentially toxic un-ionized ammonia contribute to the low oxygen levels. Un-ionized ammonia is a concern due to its toxic potential to fish and invertebrates at the high temperature (75 to 86 degrees F) and pH ranges observed (7.0 to 10.3) within the refuges (MacCoy 1994 and Bennett 1994).
Literature review presented by Bennett (1994) documented the upper limit of temperature tolerance for the fish species found in the refuges. Temperatures exceeding these limits have been observed in the 1994 study by MacCoy (1994). Significance of the high temperatures becomes even more important when considering other environmental factors such as low dissolved oxygen, high pH, and un-ionized ammonia concentrations, all of which potentially limit fish survival with the refuges. Elevated temperatures result both from shallow water and repeated use of water for irrigation.
At Tule Lake and Lower Klamath NWRs, there is concern about the limitations that poor or degraded water quality have on aquatic habitat and species survival. Aquatic habitat on the refuges is degrading, which in turn, affects aquatic plant and animal species, including wetland plants, inveterbrate animals (e.g., insects and snails), and fish species including the endangered suckers.
Since Tule Lake and Lower Klamath NWRs were originally wetlands and/or lake, all dryland habitats have been artificially created. Very little documentation exists on how these dry land types, outside of farming, have changed through time. It is known that the remaining wetlands, often referred to as sumps, are degrading rapidly (Jim Hainline, U.S. Fish and Wildlife Service, personal communication, June 28, 1996).
Historically, the Klamath and Lost River basins supported abundant fisheries resources (Cope 1879; Gilbert 1898; and Coots 1965). Within the management areas of the Tule Lake and Lower Klamath NWRs, fish habitat has been greatly degraded over the last century (Moyle 1976; Coots 1965). This is also supported by Littleton (1993). Suitable fishery habitat is dependent on water quantity of sufficient water quality, delivered or available at a specific location(s), for fish species life cycle requirements. Physical habitat requirements must provide for spawning, nursery, feeding, rearing, and refuge from predation or adverse environmental conditions. In addition, habitat corridors must be available to permit fish to move from one type of habitat to another. Biological conditions are also part of the habitat. These components include food supply, competition, predation, disease, and parasitism. Factors responsible for habitat degradation within the refuge boundaries are damming of rivers, dredging and draining of wetlands, flow diversions, over-enrichment of water from nutrients, high sediment loads, low dissolved oxygen concentrations, high water temperatures, and invasion of non-native fish. The loss of habitat has put the survival of certain species at risk (White et al. 1994).
Fisheries investigations have shown that the loss of habitat and habitat diversity has led to reduced populations of Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) (Moyle 1976; Coots 1965). Both suckers are native to Tule Lake and its historic wetlands, as well as to Lost River (Cope 1879; Gilbert 1898). These fish have been placed on the endangered species list by the Service and state agencies of Oregon and California. It is known that these fish exist within Tule Lake, and the ADY canal near Lower Klamath Refuge. The lack of deep-water habitat within Lower Klamath Refuge precludes a sustained population of either sucker. The juveniles found in the ADY canal probably were flushed from the river into the canal during water management activities. (Mark Buettner, Reclamation, Klamath office, personal communication, January 29, 1997). Limited spawning of the Tule Lake population occurs at Anderson Rose Dam. This may be sustaining the Tule Lake population; however this has not been definitively established.
While other native fish species maybe at risk, little data are available to indicate population dynamics. This is particularly true for tui chub (Gila bicolor) and blue chub (Gila coerulea). Certainly, current agricultural practices are affecting their survival. The same factors affecting the endangered suckers may be affecting these species.
Loss of suitable habitats to support spawning, nursery, and feeding, as well as refuge from predation and water quality stresses, have been severely limited and disconnected (Moyle 1976). Lack of water movement through the system due to backwater storage within the sumps has resulted in physical loss of habitat by sedimentation, increased water temperatures, and low dissolved oxygen concentrations (Coots 1965). Fertilization and erosion of farmlands is causing over-enrichment of nutrients to the aquatic system. This is resulting in a limited diversity within the phytoplanktonic and rooted aquatic plant communities, algal blooms, and reduced water quality.
Under the current management practices for agriculture, the wetland sump systems are not providing for successful reproduction and rearing of fish. The artificial character of the sumps and poor environmental quality have allowed the sucker population to approach collapse and extinction within the Tule Lake Refuge area. Recruitment (reproductive) failure is the main reason for this imbalance within the fisheries community (White et al. 1994).
According to the Service, wildlife and habitat values of the Tule Lake wetlands have declined over the last 30 years (Mauser 1994). The cited reasons for this decline are 1) filling of the sumps with sediment, 2) stabilized water levels within the wetlands, 3) lack of habitat diversity, 4) poor water quality, and 5) chemical contaminants.
The decline in value of the Tule Lake wetlands as fisheries and wildlife habitats has led to a pilot project in farmland/wetland rotation to attempt to enhance the wetlands while still providing for agriculture. This is called sump rotation. Management of the refuge lands by sump rotation will alternate the flooded and non-flooded periods for a given area of wetland. Specifically, a given area will be ponded for a varying period of time to provide fish and wildlife habitat, and to condition the soil for agricultural use in the next period. After a given amount of time, depending on the specific management objective for the area, the ponded area will be drained and used for agricultural production for a number of years. Several areas within the refuge will be in different stages of flood/dry maintenance. A brief description of sump rotation follows because the IPM process eventually will include sump rotation as a management alternative. In addition, it is desirable to begin understanding the attainable benefits to wildlife and for pest management. However, the pilot sump rotation study will not be completed until 1999. Hence site-specific data on pest management benefits and optimum rotational periods are not defined yet. "We hope to implement sump rotation as a part of IPM, but only if the pilot project yields positive IPM results" (Robert Davis [Reclamation] and Tom Stewart [Service], in a letter to Wendall Wood, Oregon Natural Resource Council, July 19, 1996).
Wetland/crop rotation has been employed successfully since the construction of the Tule Lake tunnel, primarily to enhance waterfowl habitat and thereby, survival of waterfowl within the Lower Klamath NWR. Based on this experience, sump rotation on the Tule Lake NWR may be an approach to address the problems confronting both sustained crop production and wildlife management while meeting the intent of the Kuchel Act. The purpose of the pilot sump rotation program "...is to return to Tule Lake NWR the ecological processes that historically produced diverse productive wetlands and deep water habitats while maintaining economically viable sustainable agriculture" (Mauser 1994).
The sump rotation research, conducted by Drs. Carol Shennan and Chris Grue, will establish the feasibility of sump rotations as a future management option for the Tule Lake NWR. The research is designed to answer some basic questions about whether the combination of short and/or long-term rotations will provide intended results. Figure 3 (60K) shows the location of the sump rotation study areas with a description of cropping and wetland programming, and illustrates potential long-term sump rotation divisions.
The major issues that need to be addressed concerning sump rotation are listed below:
According to the "Sump Rotation Newsletter" (Issue No. 1, Winter 1996) the pilot sump rotation project is testing two types of rotational cycles: short-term and long-term. Short-term sump cycling is designed to have limited flooding duration. Flooding of the land will be limited to seasonal periods so that perennials will not be able to establish. Specifically, the short-term sump cycle is a 7-year program with 4 years of cropping, 2 years of seasonal flooding, and 1 year of continuous flooding. It is hoped that submersed aquatic plants will colonize the sumps during flooding periods. The organic materials produced by these plants and algae will increase soil fertility while the flooding may reduce soil pathogens. Long-term sump rotation is a 40-year cycle divided into two 20-year periods: 20 years of flooding or wetland habitat and 20 years of continuous crop production. During the 20-year period as a wetland, it is assumed that emergent and submersed plants will develop and a mature marsh environment will establish itself.
The sump rotation pilot study is collecting data on crop response, crop rotation, topography, cropping history, crop management, water flows, soil characteristics, vegetation patterns, economic impacts, water quality, weed seed viability, key soil pathogens, nematodes, soil nutrient cycling, fish and wildlife monitoring within the sump rotation management areas, habitat inventory of both aquatic and sub-aquatic areas, and waterfowl utilization. These data will be used to develop costs/benefits for various sump rotation strategies. One of the sumps will be designed specifically as sucker habitat.
It is expected that the sump rotation program will generate benefits to both agriculture and fish and wildlife on the Tule Lake NWR. Specifically, the agricultural community is looking for a reduction in soil pests and pathogens, reduced need for fertilizers and pesticides, and sustainability of cash crops. On the other hand, fish and wildlife managers and concerned environmental groups are hoping that endangered species will use the refuge to a greater degree and therefore enhance species survival (specifically the bald eagle and shortnose and Lost River suckers). They also expect migrant waterfowl, shorebirds, and nesting water birds to use the refuge. In general, sump rotation is expected to increase wildlife species diversity of the refuge.
The sump rotation pilot study is being funded by grants from the USDA and support from U.C. Davis. Engineering costs for construction of the pilot sump sites have been funded by the Service and Reclamation. Wildlife studies are funded by the National Biological Service with in-kind support from Service refuge staff.
Return to the IPM Plan Table of Contents or continue on to B. Overview of Current Agricultural and Pest Management Practices
