SUGAR CREEK WATER YIELD ENHANCEMENT STUDY
STATEMENT OF WORK
SCOTT RIVER COOPERATIVE RESTORATION PLANNING GROUP*
APRIL 10, 2013
The Scott River is a tributary to the Klamath River in far Northern California that supports a large portion of the Klamath Riverís coho salmon run. Coho Salmon in the Klamath Basin are listed as threatened under both the State and Federal Endangered Species Acts. The Scott River is also listed as impaired under section 303(d) of the Clean Water Act for stream temperature and sediment. Much of the fishery and water quality problems are related to low flows in the summer months that contribute to high stream temperatures and reduce the quantity of rearing and spawning habitat. In dry years, segments of the main stem of the Scott River dry up, and salmonoid refugia habitat is located in smaller upland tributaries. Stream flows are often too low for the early fall migration of anadramous species. Fish migration is blocked from passing multiple reaches of the main-stem and many tributary mouth gravel deposits until river flows are restored by the seasonal evapotranspiration cessation of upland vegetation and annual major fall storms add significant precipitation within the watershed.
Habitat regulatory requirements for the Northern Spotted Owl and other listed species include the development and retention of high levels of forest density to meet the demands of a closed canopy environment. The inclusion of these requirements on public and private lands within the range of the NSO has modified most forest harvest entries to low intensity thinning. Most of the increased forest densities and the shift to mixed conifer from ponderosa pine forest types within the watershed is a result of a rapid expansion of white fir understory established post fire suppression, circa 1950. Most forested areas within the basin have documented a 2 to 4 fold departure from the historic reference 15 year fire reentry period and an associated forest vegetative densification.
The University of California at Davis is currently conducting an investigation of the impacts of groundwater use on surface flows as a requirement of the Scott River TMDL (Harter, 2008). The study is developing a water balance that includes water use by vegetation and agriculture in the alluvial valley bottom, but does not account for changing conditions in forest density on upslope lands and the east side Juniper/Pine Biome found in the Scott River Watershed.
It is hypothesized that the low flows in the Scott River are partially due to an increase in evapotranspiration caused by an increase in forest vegetative density, the loss of snow fields in high elevation basins and shifts in forest stand age distributions. Fire suppression over the past century has caused local forests to change from low-density ponderosa pine to high-density mixed conifer stands with an associated rapid localized expansion of white fir topographic distribution. The local public is requesting that forest treatments be designed to simultaneously restore stream flows for salmon, reduce the threat of high-severity wildfires, and produce commercial timber products.
The goal of this study is to investigate relationships between stream water yield and upland forest densities in the Sugar Creek Sub-watershed of the Scott River, and to quantify any potential to enhance water yield in the Scott River by managing upslope forest vegetation. Potential yield will be studied and compared using three vegetative conditions.
1. Pre-fire suppression forest densities using 1940ís aerial photography, the earliest local reliable data source for vegetation.
2. Current water yields using current vegetative condition within the watershed.
3. Projected water yield changes due to critical habitat designation specified by the 2012 NSO Recovery Plan.
SCOPE OF WORK
The analysis area is the Sugar Creek watershed (HUC 180102080204). A less intensive analysis will be completed for the Scott River sub-basin upstream from the US Geological Survey stream gauge (11519500), excluding agricultural lands.
Develop a Study Plan:
a. The Consultant will develop a draft project plan including a study design, schedule, and proposed budget.
b. The plan will include a review of the literature and its relevance to conditions in the Scott River. It will include a review of conditions in the Scott River basin in order to develop hypotheses regarding the impact of forest management actions on the forest water balance.
c. Carry out a site visit to assess local conditions, assess data availability, and meet with Scott River Cooperative to help define scope of study.
d. The Consultant will submit a final study plan that incorporates any relevant comments and issues identified at the public meeting in task #2.
e. Meet with advisory committee to review the study design
f. Draft Study Plan
g. Final Study Plan
Presentation of project design:
a. Consultant will present the draft project plan to the Cooperative. Conduct a question and answer session to identify issues to include in the final study plan. Provide written answers to written questions. Transcribe oral questions. Present draft and final project plan in an online format, via the www.
a. Simulate the hydrologic responses found in the objectives that can be expected to occur under: (1) current conditions (2) historic conditions (3) conditions meeting the proposed vegetation treatments required to address the current critical habitat requirements for management of the Northern Spotted Owl. The modeling approach should provide a quantitative estimate of water-yield, and the magnitude and timing of low flows and peak flows.
b. Compile and analyze relevant data for hydrologic and linked vegetation modeling
c. Meet with advisory committee
d. Two additional site visits to Siskiyou County.
e. Draft Report
f. Final Report
g. Develop a web presence for all data and modeling results
Presentation of results:
a. UC will present the draft findings to partners for review and comment.
b. Provide written answers to written questions. Transcribe oral questions. Present draft and final project plan in an online format, via the www.
Acceptance of Work
The acceptance of all deliverables will reside with Scott River Cooperative.
PERIOD OF PERFORMANCE
The period of performance for the Project is one year (365 days) beginning on 2 March 2013 through 3 March 2014. Upon agreement by both parties, the work may be extended for 2 or more years if needed or if the items listed under additional work are completed.
INFORMATION SUPPLIED BY THE SCOTT RIVER COOPERATIVE
1. The Cooperative will provide data relevant to the project to the contractor. This includes spatial data, vegetation data, and other information relevant for meeting objectives.
2. A GIS Specialist to assist with analysis.
3. Field crew, if needed to collect data on current conditions, etc.
4. Vegetation descriptions for forest species, structure, and stocking levels under
- Historic pre-fire suppression conditions.
- Current conditions
- Treatment prescriptions for a range of scenarios
Develop guidance for hydrologists to assess the cumulative effects of future vegetation management on water yields and hydrographs using a researcher recommended model.