Executive Summary Executive Summary This report presents details of the investigation and results in estimating the natural flow of the upper Klamath River at Keno, Oregon. The area investigated includes the Klamath River Basin above Keno, Oregon, primarily in Klamath County, with some areas of Siskiyou and Modoc Counties in California. The study area includes the Sprague, Williamson, and Wood River basins, as well as Upper Klamath and Lower Klamath Lakes. Objectives The current purpose of this study is to provide an estimate of the monthly natural flows in the upper Klamath River at Keno. This estimate of the natural flow represents typical flow without agricultural development in the Upper Klamath River Basin, including its tributaries. Study Approach This study used a water budget approach to assess the agricultural depletions and alterations to the natural flow. The approach was to evaluate the changes of agriculture from predevelopment conditions, estimate the effects of these changes, and restore the water budget to natural conditions by reversing the effects of agricultural development. Records used in this empirical assessment were derived from both stream gaging flow histories and from climatological records for stations within and adjacent to the study area. Water Budget Description The water budget assessment of the watershed as a natural system includes an evaluation of hydrological changes related to agricultural development above the Keno gage. The water budget assessment includes: ? Natural inflow from the Sprague, Williamson, and Wood Rivers to Upper Klamath Lake ? Predevelopment evapotranspiration losses from marshes surrounding Upper Klamath Lake ? Predevelopment evaporation losses of the Upper Klamath Lake ? Natural flow at the outlet of Upper Klamath Lake into the Link River at Klamath Falls ? Resulting natural flow at Keno The processes developed in the water budget to evaluate the natural outflow of Upper Klamath Lake accounts for factors related to water resources developments XI Natural Flow of the Upper Klamath River in the watershed that have affected inflow to the lake, and for losses due to natural condition of the lake. The water budget assessment of the watershed as a natural system includes an evaluation of hydrological changes related to agricultural development above the Keno gage. The results of the water budget assessment are given as average annual flows for two important stream gages, one located on the Link River at Klamath Falls and the other on the Klamath River at Keno. Evaluation of Predevelopment Conditions An evaluation of predevelopment conditions included an evaluation of changes to Upper Klamath Lake, agricultural developments in the Wood River, Sprague River, and Williamson River watersheds. Several basic elements were considered in this study: ? How had development changed the system ? Was information available about conditions before the changes occurred ? Were data available to assist in estimating changes to the natural system Evaluation of Current Conditions Period of Record The period of record considered in this investigation is the 52 years from 1949 to 2000. This period of record was chosen because hydrologic and climatological data were limited for the pre-1949 period and data beyond 2000 were not available when the study began. The water year convention (October through September) is used in this report. Crop and Marshland Evapotranspiration Analysis The modified Blaney-Criddle method was used to determine potential net evapotranspiration (ET) from crops, marshlands, and riparian zones. The method is empirical and the calculated values were adjusted based on other recent study findings and water limiting considerations. To estimate net ET water consumption by this method requires the following data: ? Location of irrigated lands, marshlands, and riparian zones ? Types of crops and number of acres for each crop ? Types and acreages of marshland and riparian vegetation, both existing and predevelopment ? Monthly precipitation and monthly average temperature for the period of record for each area Methods to Estimate Natural Flows Natural streamflow development included adjustment of gaged streamflow to natural flow, restoration of missing streamflow and climate data, making natural streamflow estimates in ungaged watersheds, assessing groundwater XII Executive Summary contributions, and estimating transit losses. Not all of these procedures were appropriate or possible in all subbasins of the study area. Records of historic flow may be adjusted to natural flow using crop net consumptive use and marshland evapotranspiration: natural flow = gaged flow + crop net consumptive use - reclaimed natural marshland net evapotranspiration Correlation analysis was used to restore missing values from monthly-value data records used in this study. The method is different from linear least-squares regression estimation. Data records used in this study include precipitation and average temperature histories, in addition to hydrologic records of streamflow and lake stage. Also, natural streamflow histories are required in ungaged watersheds to assess the natural inflow to Upper Klamath Lake. Sparse monthly flow records for streams heading on the east flank of the Cascades and flowing into the Wood River Valley or Pelican Bay area of Upper Klamath Lake required estimation techniques that used gaged histories from nearby river basins. These data were evaluated in statistical applications to yield natural flow estimates for these ungaged portions of the Klamath Basin. In a similar vein, groundwater contributions required temporal adjustments attributable to the climate signature evident in longer term records for similar groundwater discharges in neighboring watersheds. Transit losses for both surface water and groundwater contributions were also estimated in this study. Natural Lake Simulations Implementation of a water budget for Upper Klamath Lake required developing information about (1) the storage and inundation surface area characteristics of the lake, and (2) the discharge characteristics at the outflow point of the lake. These characteristics were evaluated in relation to the elevation, or stage, of the water surface of the lake. Additionally, discharge from the lake was also related to the stage. Estimating the outflow of a natural lake is accomplished using a water budget approach. A monthly summation of all elements in the water budget may be stated by the general form of the hydrologic equation: i = o + As where i = inflow to the lake o = outflow from the lake and As = change in storage of the lake XIII Natural Flow of the Upper Klamath River For Upper Klamath Lake, the month-to-month water budget accounts for natural inflow, storage of water within each lake, resulting estimated lake stage, and discharge from each lake. In addition, open water surface evaporation and groundwater discharge to the lake from the regional aquifer were estimated. The water budget assessment was designed to simulate the lake as a natural water body. Materials and Data Researched and Used Data Sources Records used in this analysis were derived from both stream gaging flow histories and from climatological records for stations within and adjacent to the study area. Information was also developed from published reports, file documents, and maps. Supporting information included documents from: ? Archives of the Bureau of Reclamation Klamath Basin Area Office ? Numerous U.S. Geological Survey (USGS) Water Supply Papers regarding stream gaging records ? Compact disk databases containing digital records of gaged flow, lake stage records, and meteorological data Anecdotal items from newspaper articles or clipped from magazines were also reviewed. These sources consisted of narratives of past events or conditions, transcripts of interviews, newspaper accounts, books, diaries, and historical journals. These provided an impression of predevelopment conditions that can be compared to the empirical and scientific information gleaned from other sources. Other reviewed materials included unpublished and out-of-print scientific reports, historical maps, letters, books, journals, and photographs. Modeling Tools Results of the water budget assessment were accomplished using Excel?, a sophisticated spreadsheet available in the Microsoft Office for Windows software package. This model was chosen over other models because this study is unique. The computational modules built as the study developed represent a custom application of Excel? to the solution of estimating the natural flow conditions in the Upper Klamath River Basin. Klamath River at Keno Gaging Station For the simulation period, 1949 to 2000, the water balance for the Upper Klamath River Basin at Keno is described below. The natural outflow (discharge) from Upper Klamath Lake at Link River was computed in the water balance. Discharge at Keno was then calculated using a correlation relationship developed between historic measured Link River and Keno flows. Table S-l presents the estimated water balance and outflow developed for the Link River and Keno gages. XIV Executive Summary Table S-1. Estimated inflow and outflow developed for Link River and Keno gages Upper Klamath Lake Acre-feet Average annual natural inflow Average annual natural net loss 1,605,000 210,000 Resulting average annual natural outflow 1,395,000 Link River to Keno Average annual natural inflow 1,485,000 Resulting average annual natural outflow at Keno gage 1,306,000 Other Factors Considered The focus of this study is agricultural development in the Upper Klamath River Basin and its effects on natural flow conditions. Other watershed factors have changed since predevelopment. Some of these factors were considered, but are unaccounted-for in the assessment, such as changes in forest conditions or an extension of the flow histories before 1949. Model Review and Sensitivity Analysis Although this study uses best available hydrologic methods and data to either measure or estimate all inflows and outflows to the system, additional concerns have arisen in completing the work. Relationships regarding the significance of uncertainty are likely to be spatially and temporally variable. The key factor is the relative importance of each module in the transit losses suffered by inflows to the natural system. The significance of these influences to model sensitivity is related to time of year or length of time over which flows are evaluated. Model sensitivity is related to uncertainty in data regarding the most significant transit losses; namely, marsh evapotranspiration and open water evaporation. The natural flows developed at Keno are realized, in part, through a statistical rule based model rather than a physically based model. This construct within the model is for the segment from the Link River gage below Upper Klamath Lake, to the Keno gage below Lower Klamath Lake. Thus, sensitivity in testing the spatial and temporal variables within the Link River to Keno reach that affect the flow at Keno is problematic. xv Natural Flow of the Upper Klamath River Summary Development of the natural flows at the Keno gage was accomplished using a spreadsheet modeling approach to resolve the water budget for the Upper Klamath River Basin under undeveloped watershed conditions. The resulting flow duration for simulated natural average monthly flows for Keno gage are described in Table S-2. The percentiles represent the flow exceedence ranges in monthly natural flow estimates at Keno solely due to record length. These percentiles are estimates for modeled baseline conditions and do not reflect data uncertainties for possible changes in evaporation, evapotranspiration, or other factors. Table S-2. Summary of simulated monthly flows at Keno in cfs % Time <= Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Annual % Time >= 10 648 1088 1216 1408 1647 1577 1670 1408 1168 631 520 560 1188 90 20 769 1159 1352 1472 1767 1689 2017 1721 1358 822 578 616 1429 80 30 857 1255 1453 1667 1925 1907 2125 2051 1664 964 706 720 1528 70 40 974 1342 1625 1845 2016 2040 2477 2280 1890 1228 767 746 1607 60 50 1033 1455 1698 1964 2343 2133 2595 2649 2039 1349 873 854 1773 50 60 1131 1523 1803 2072 2410 2360 3009 2827 2388 1478 998 955 1903 40 70 1224 1576 1984 2196 2615 2703 3146 3131 2657 1706 1154 1049 2169 30 80 1304 1739 2049 2399 2829 3115 3615 3385 3104 2210 1351 1210 2347 20 90 1488 1815 2319 2659 3294 3367 3877 3707 3460 2923 1684 1412 2511 10 A simplified flowchart depicting the overall sources of included inflow and outflow variables has been completed as figure S-l, with average annual values shown from each source. XVI
"November 2005."