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Bureau of Land Management Research Needs
TITLE:
Effects of Siltation and Salinization
of the San Juan River on the Survival and Recovery of the
Colorado Squawfish and Razorback Sucker
SUBMITTING BUREAU: Bureau of Land Management
Originating Offices: Farmington District Office, Farmington, New Mexico
BIN NUMBER: BLM04CR98
BRD REGION: Central
DESCRIPTION OF NEED: The San Juan River originates high in the San Juan Mountains of southwestern Colorado and flows in a southwesterly to westerly direction where it ends at the confluence with the Colorado River in Utah. The majority of the San Juan River flows through a semi-desert region covered with sparse vegetation and highly erosive soils that are formed mainly from sandstone and shale parent materials. Historically, the San Juan River has been a sandy, silt laden river. Personal journals and logs kept by early explorers, fur trappers, and settlers that ventured into the region mention the high levels of the sand and silt content of the San Juan River.
To date, studies have focused on historical flows and simulation of the natural hydrograph and its relationship to the survival of the Colorado squawfish and the razorback sucker, as well as heavy metals impacts and polynuclear aromatic hydrocarbon toxicity below the Navajo Dam.
Bureau of Reclamation's water releases from Navajo Dam have been successful in simulating the natural hydrograph based on historical flow data prior to the construction of the dam. However, the quality of water used is different than pre-dam era due to the reservoir's effects both on solids settling and chemical reactions.
Investigations into the effects of silt and salt contents of the San Juan River water and its relationship to the survival and recovery of the Colorado squawfish and razorback sucker are non-existent or un-published. BLM feels that siltation differences and salinization differences may have changed the habitat and water quality characteristics that the species prefer. The effects of erosion below the dam may also appear more drastic since the dam was constructed because the upper sections of the San Juan, Piedra and the Los Pinos Rivers have been contained, with 30 miles of lake to settle their contents. They may, in fact, be more impacted due to road development in the San Juan Basin, but there is little to no documentation of sediment loading in the area.
Detailed need:
1. Historical review of siltation and salinization of the San Juan River prior to construction of man made dams.
2.Effects of silt and salt content of the San Juan River water and its relationship to the survival of the Colorado squawfish and razorback sucker.
3.Effects of solids settling and chemical reactions due to reservoirs and their effect on the survival and recovery of the Colorado squawfish and razorback sucker.
4.Impacts of road development in the San Juan Basin and their impact on sediment load in the area.
MANAGEMENT PROBLEM WITH NEED: To further the understanding of proposed and ongoing oil and gas leasing and development activities and the likelihood of jeopardizing the survival and recovery of the Colorado squawfish and razorback sucker through the degradation of the aquatic habitat in the San Juan River.
There is a general concern about the water quality and its impacts to the recovery of Colorado squawfish and razorback sucker, both endangered species.
BUREAU CONTACTS: Joel Farrell 505-599-6310
(Stephanie Odell, (505)-599-6314, sodell@nm0151wp.nmso.nm.blm.gov, Dale Wirth, (505) 599-6320, dwirth@nm0151wp.nmso.nm.blm.gov)
BRD PRIMARY CENTER: ECRC
BRD CENTER CONTACT: Steve Hamilton
RESULTS OF BRD-INITIATED COMMUNICATION (FY99): Studies in the San Juan Basin by BRD, BLM, and FWS have focused on historical flows and simulation of the natural hydrograph and its relationship to the survival of the Colorado squawfish and the razorback sucker, as well as potential toxicity of irrigation drainwater, heavy metals, and polynuclear aromatic hydrocarbons below the Navajo Dam. BLM feels that siltation differences and salinization differences may have changed the habitat and water quality characteristics that the species prefer. The effects of erosion below the dam may also appear more drastic since the dam was constructed because the upper sections of the San Juan, Piedra and the Los Pinos Rivers have been contained, with 30 miles of lake to settle their contents. BRD has been in contact with BLM to discuss San Juan Basin issues in April, May, July, and August of 1998. ECRC has also presented information on BRD projects conducted in cooperation with BLM at several national meetings and most recently discussed the methods for interpreting the effects of salinity and siltation as two of many stressors affecting fisheries in that system. ECRC is using information from several studies conducted in this basin to evaluate the relative importance of different ecological factors on the success of razorback suckers and Colorado squawfish. Issues associated with salinization in the San Juan River link directly to irrigation input. Existing studies have documented increases in water salinity as the river moves downstream from Navajo Dam. Recently completed studies on benthic invertebrate communities are being used to evaluate the level of siltation in stretches of the river below Navajo Dam and determine the quality of the habitat. Because of the many anthropogenic changes in this basin, it will be impossible to attribute reduced numbers of razorback suckers and Colorado squawfish to a single cause. However, it may be possible to determine the relative importance of multiple stressors in determining population success. ECRC has been involved in projects in the San Juan Basin since 1994. Contacts with Joel Farrel and other BLM contacts will continue on a regular basis.
DATE SUBMITTED TO REGIONAL OFFICE: December 18,1998
PREPARED BY: Steve Hamilton and Susan Finger (CERC)
RESULTS OF BRD-INITIATED COMMUNICATION (FY98): BRD studies during the past three years have investigated the effects of potential oil and gas development on aquatic resources in the San Juan River. The final report is near completion and should be in the hands of BLM’s Farmington, NM office by March. Additional work has been completed on the effects of inorganic elements associated with irrigation practices on the flannelmouth sucker in the San Juan River. Both studies have investigated issues that relate to salinization in the San Juan River. Both studies have also shown increases in water salinity as the river moves downstream from Navajo Dam. Habitat quality which includes aspects of siltation has also been addressed in a separate study with information to be available within the year. Of the four detailed needs listed in this BIN, information is currently available for the potential effects of the salinity and associated contaminants on the survival of native fishes. Attempts will be made to identify resources to compile a historical review of siltation and salinization of the San Juan river prior to dams.
DATE SUBMITTED TO REGIONAL OFFICE: November 14, 1997
PREPARED BY: Steve Hamilton, Environmental and Contaminents Research Center, Field Research Station, Yankton, RR 1, Box 295, Yankton, SD 57078-9214, 605-665-9217 and Susan Finger, Environmental and Contaminents Research Center, 4200 New Haven Road, Columbia, MO 65201, 573-875-5399-1850
U.S. Department of the Interior | U.S. Geological Survey
URL: http://biology.usgs.gov/cro/98blm-4.htm
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