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• 721. [Image] Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency Lakes, Oregon

  	Two maps digitized separately; Includes bibliographical references (p. 44-49)
  	Citation × Citation Citation Abstract Copy Title: Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency Lakes, Oregon Author: Snyder, Daniel T. Year: 1997, 2005, 2004 Two maps digitized separately; Includes bibliographical references (p. 44-49) Title: Nitrogen and phosphorus loading from drained wetlands adjacent to Upper Klamath and Agency Lakes, Oregon Author: Snyder, Daniel T. Year: 1997, 2005, 2004 Two maps digitized separately; Includes bibliographical references (p. 44-49) Close

• 722. [Image] Effect of water-column pH on sediment-phosphorus release rates in Upper Klamath Lake, Oregon, 2001

  	Abstract Sediment-phosphorus release rates as a function of pH were determined in laboratory experiments for sediment and water samples collected from Shoalwater Bay in Upper Klamath Lake, Oregon, in 2001. ...
  	Citation × Citation Citation Abstract Copy Title: Effect of water-column pH on sediment-phosphorus release rates in Upper Klamath Lake, Oregon, 2001 Author: Fisher, Lawrence H. Year: 2004, 2005 Abstract Sediment-phosphorus release rates as a function of pH were determined in laboratory experiments for sediment and water samples collected from Shoalwater Bay in Upper Klamath Lake, Oregon, in 2001. Areal release rates for a stable sediment/water interface that is representative of the sediment surface area to water column volume ratio (1:3) observed in the lake and volumetric release rates for resuspended sediment events were determined at three different pH values (8.1, 9.2, 10.2). Ambient water column pH (8.1) was maintained by sparging study columns with atmospheric air. Elevation of the water column pH to 9.2 was achieved through the removal of dissolved carbon dioxide by sparging with carbon dioxide-reduced air, partially simulating water chemistry changes that occur during algal photosynthesis. Further elevation of the pH to 10.2 was achieved by the addition of sodium hydroxide, which doubled average alkalinities in the study columns from about 1 to 2 milliequivalents per liter. Upper Klamath Lake sediments collected from the lake bottom and then placed in contact with lake water, either at a stable sediment/water interface or by resus-pension, exhibited an initial capacity to take up soluble reactive phosphorus (SRP) from the water column rather than release phosphorus to the water column. At a higher pH this initial uptake of phosphorus was slowed, but not stopped. This initial phase was followed by a reversal in which the sediments began to release SRP back into the water column. The release rate of phosphorus 30 to 40 days after suspension of sediments in the columns was 0.5 |ig/L/day (micrograms per liter per day) at pH 8, and 0.9 |ug/L/day at pH 10, indicating that the higher pH increased the rate of phosphorus release by a factor of about two. The highest determined rate of release was approximately 10% (percent) of the rate required to explain the annual internal loading to Upper Klamath Lake from the sediments as calculated from a lake-wide mass balance and observed in total phosphorus data collected at individual locations. Title: Effect of water-column pH on sediment-phosphorus release rates in Upper Klamath Lake, Oregon, 2001 Author: Fisher, Lawrence H. Year: 2004, 2005 Abstract Sediment-phosphorus release rates as a function of pH were determined in laboratory experiments for sediment and water samples collected from Shoalwater Bay in Upper Klamath Lake, Oregon, in 2001. Areal release rates for a stable sediment/water interface that is representative of the sediment surface area to water column volume ratio (1:3) observed in the lake and volumetric release rates for resuspended sediment events were determined at three different pH values (8.1, 9.2, 10.2). Ambient water column pH (8.1) was maintained by sparging study columns with atmospheric air. Elevation of the water column pH to 9.2 was achieved through the removal of dissolved carbon dioxide by sparging with carbon dioxide-reduced air, partially simulating water chemistry changes that occur during algal photosynthesis. Further elevation of the pH to 10.2 was achieved by the addition of sodium hydroxide, which doubled average alkalinities in the study columns from about 1 to 2 milliequivalents per liter. Upper Klamath Lake sediments collected from the lake bottom and then placed in contact with lake water, either at a stable sediment/water interface or by resus-pension, exhibited an initial capacity to take up soluble reactive phosphorus (SRP) from the water column rather than release phosphorus to the water column. At a higher pH this initial uptake of phosphorus was slowed, but not stopped. This initial phase was followed by a reversal in which the sediments began to release SRP back into the water column. The release rate of phosphorus 30 to 40 days after suspension of sediments in the columns was 0.5 |ig/L/day (micrograms per liter per day) at pH 8, and 0.9 |ug/L/day at pH 10, indicating that the higher pH increased the rate of phosphorus release by a factor of about two. The highest determined rate of release was approximately 10% (percent) of the rate required to explain the annual internal loading to Upper Klamath Lake from the sediments as calculated from a lake-wide mass balance and observed in total phosphorus data collected at individual locations. Close

• 723. [Image] Ground water hydrology of four proposed project areas in the Klamath Basin, Oregon

  	"OF-01-01"
  	Citation × Citation Citation Abstract Copy Title: Ground water hydrology of four proposed project areas in the Klamath Basin, Oregon Author: Oregon. Water Resources Dept Year: 2001, 2005 "OF-01-01" Title: Ground water hydrology of four proposed project areas in the Klamath Basin, Oregon Author: Oregon. Water Resources Dept Year: 2001, 2005 "OF-01-01" Close

• 724. [Image] Farming practices and water quality in the Upper Klamath Basin : final report to the California State Water Resources Control Board : 205j program

  	Summary The Upper Klamath Basin (UKB) is a high desert region straddling the California-Oregon border east of the Cascade Range. Irrigation and other agricultural practices in the U. S. Bureau of Reclamation's ...
  	Citation × Citation Citation Abstract Copy Title: Farming practices and water quality in the Upper Klamath Basin : final report to the California State Water Resources Control Board : 205j program Author: Danosky, Earl; Kaffka, Stephen Year: 2002, 2007, 2006 Summary The Upper Klamath Basin (UKB) is a high desert region straddling the California-Oregon border east of the Cascade Range. Irrigation and other agricultural practices in the U. S. Bureau of Reclamation's Klamath Project may result in impaired surface water quality, reducing its use for wildlife and fish in important national wildlife refuges that receive drainage water from farms, and in the Klamath River. By 2004, a system of total maximum daily loads (TMDL) for nutrients must be established for the Klamath River. To investigate the relationships among agricultural practices and surface water quality in the Upper Klamath Basin, a two year reconnaissance survey of surface water and agricultural tile drain locations, focusing on nitrogen and phosphorus concentrations and mass transfers was conducted. Data was collected at 18 surface locations and 10 tile drain locations. Triplicate samples were taken every ten days during the growing season (April through October) and one or two times a month during the remainder of the months, depending on opportunity. No samples were taken from tile drains during the winter months because there was no irrigation and drainage during that period. Water samples were analyzed for phosphorus (total P, soluble reactive P, total filterable P, and particulate P) and nitrogen (total N, soluble N, Soluble organic N, total filterable N, particulate N, and ammonia N), temperature, pH and electrical conductivity, a measure of salinity or total dissolved solids. Analyses of data, including data quality, estimates of the transfer of nutrients in surface waters in the region, and hypotheses about the relationship between agriculture and water quality are reported. 1. The salt and nutrient content of surface waters increases nearly threefold as water moves through the watershed from the Lost River and J canal diversion to the Klamath Straits Drain. Mean ECW levels in input waters at the J canal diversion were approximately 250 \iS cm1, while water sampled at the D pump increased to 600 ^S cm"1 on average over the sample period. By the time water reenters the Klamath River, salt concentrations have increased to approximately 700 jaS cm1. 2. The ECW values observed in subsurface tile drains were higher on average than in input waters and surface waters elsewhere in the region, especially in the Lease Lands area of the Tulelake Irrigation District (TID). ECW values averaged approximately 2,500 ^S cm"1 . Recycling irrigation water through soils in the TID increases the salinity of the water, especially by the time it reaches and is reused in the Lease Lands area of the Tulelake National Wildlife Refuge (TLNWR). Soils in this part of the Klamath Project area are naturally high in salt. 3. Water temperatures in agricultural subsurface tile drains were significantly lower than surface water temperatures during the growing season when tile drains were active. pH values in tile drains were lower than surface water values. The temperature and pH of tile drains does not influence surface water values. 1. 4. For total phosphorus (TP) input waters at the J canal irrigation diversion for the TED averaged approximately 0.27 mg L1 for the two years reported. Water leaving the Tulelake Sumps at the D pump increases to 0.33 mg L1. Water leaving the Lower Klamath National Wildlife Refuge (LKNWR) sampled at the start of the Klamath Straits Drain, averaged 0.33 mg L1, similar to those at the D pump. TP increased further to 0.40 mg L"1 a the end of the Klamath Straits Drain. The overall increase in P concentration in surface waters was much less than for salt, suggesting that processes other than simple enrichment are occurring, particularly those associated with the exchange of sedimentary P and aquatic plant species. TN increases from 2.3 mg L"1 to 4.0 mg L1 over the same pathway. Atomic ratios (TN:TP) of surface water samples remain constant at approximately 10:1 throughout the system, suggesting that the amount of sediment and other small particulate matter in surface waters affects the values observed. The amount of sediment is influenced in part by the agitation of surface water as it passes through pumps and over weirs. 5. The average seasonal TP value in tile drains beneath farm fields is approximately 0.34 mg L"1 . While average total P values in subsurface tile drains were not different from those found at the D pump and the LKNWR outlet, the range in values was great (0.1 to 0.8 mg L1). Similarly, high NO3 -N values were observed at times in tile drains. Very high values in tile drains lead to the inference that some fertilizer N and P is lost in drainage water, combined with nutrients derived from decaying soil organic matter. The amount estimated as lost is much less than the amount of surplus fertilizer P applied and the amount of P surmised to be mineralized from decaying soil organic matter. P from fertilizer and decaying organic matter appears to be accumulating in soils and lake sediments in the region. 6. Ammonia N concentrations are at or below the limit of detection in subsurface agricultural tile lines and one to two orders of magnitude below the values observed in surface soils. Un ionized ammonia increases with temperature. Values above 0.25 mg L1 were observed in late summer at several locations. 7. Some leaching of soluble salts and nutrients is unavoidable when crops are irrigated. P fertilizer is applied at rates higher than crop removal, while fertilizer n is applied at rates less than crop removal. Reduced fertilizer use can help bring P inputs and outputs into balance and may reduce further any avoidable losses of P. This objective should be the subject of an agronomic research program in the region. 8. Surface waters entering the TDD, the TLNWR, and the LKNWR are already enriched with N and P. It seems unlikely that reducing N and P losses from farming in the TID, if possible, would influence surface water quality sufficiently to make them significantly less eutrophic. For P, the hypothesized threshold concentration limiting algae growth in fresh waters is 5 to 25 times smaller than the values observed in waters entering the TID for irrigation use. The addition of 1. nutrients from agriculture probably does not influence significantly surface water quality in the region. Wetland sediments, large amounts of organic matter in soils, and water introduced for irrigation contain essentially unlimited amounts of nutrients for aquatic plant growth. It is not clear how this circumstance could be changed under any reasonable time frame, if ever. 9. Using a TMDL approach may not result in reduced amounts of nutrients returned to the Klamath River because wetlands and farming practices in the southern portion of the Klamath Project result in the net removal of nutrients from the waters diverted for irrigation on a yearly basis, compared to allowing the same amount of water simply to flow down the river unused. Because of large errors of estimation for the amounts of water transferred, combined with smaller errors associated with estimating nutrient concentrations in water samples, and with year to year climate variation, TMDLs may not be an effective or efficient means of reducing nutrients in return flows to the Klamath River. Rational confidence limits for TMDLs may have to be too broad to be effective. Recycling of some drainage water for irrigation would reduce the amount of nutrients returned to the river more effectively than implementing a TMDL program. Title: Farming practices and water quality in the Upper Klamath Basin : final report to the California State Water Resources Control Board : 205j program Author: Danosky, Earl; Kaffka, Stephen Year: 2002, 2007, 2006 Summary The Upper Klamath Basin (UKB) is a high desert region straddling the California-Oregon border east of the Cascade Range. Irrigation and other agricultural practices in the U. S. Bureau of Reclamation's Klamath Project may result in impaired surface water quality, reducing its use for wildlife and fish in important national wildlife refuges that receive drainage water from farms, and in the Klamath River. By 2004, a system of total maximum daily loads (TMDL) for nutrients must be established for the Klamath River. To investigate the relationships among agricultural practices and surface water quality in the Upper Klamath Basin, a two year reconnaissance survey of surface water and agricultural tile drain locations, focusing on nitrogen and phosphorus concentrations and mass transfers was conducted. Data was collected at 18 surface locations and 10 tile drain locations. Triplicate samples were taken every ten days during the growing season (April through October) and one or two times a month during the remainder of the months, depending on opportunity. No samples were taken from tile drains during the winter months because there was no irrigation and drainage during that period. Water samples were analyzed for phosphorus (total P, soluble reactive P, total filterable P, and particulate P) and nitrogen (total N, soluble N, Soluble organic N, total filterable N, particulate N, and ammonia N), temperature, pH and electrical conductivity, a measure of salinity or total dissolved solids. Analyses of data, including data quality, estimates of the transfer of nutrients in surface waters in the region, and hypotheses about the relationship between agriculture and water quality are reported. 1. The salt and nutrient content of surface waters increases nearly threefold as water moves through the watershed from the Lost River and J canal diversion to the Klamath Straits Drain. Mean ECW levels in input waters at the J canal diversion were approximately 250 \iS cm1, while water sampled at the D pump increased to 600 ^S cm"1 on average over the sample period. By the time water reenters the Klamath River, salt concentrations have increased to approximately 700 jaS cm1. 2. The ECW values observed in subsurface tile drains were higher on average than in input waters and surface waters elsewhere in the region, especially in the Lease Lands area of the Tulelake Irrigation District (TID). ECW values averaged approximately 2,500 ^S cm"1 . Recycling irrigation water through soils in the TID increases the salinity of the water, especially by the time it reaches and is reused in the Lease Lands area of the Tulelake National Wildlife Refuge (TLNWR). Soils in this part of the Klamath Project area are naturally high in salt. 3. Water temperatures in agricultural subsurface tile drains were significantly lower than surface water temperatures during the growing season when tile drains were active. pH values in tile drains were lower than surface water values. The temperature and pH of tile drains does not influence surface water values. 1. 4. For total phosphorus (TP) input waters at the J canal irrigation diversion for the TED averaged approximately 0.27 mg L1 for the two years reported. Water leaving the Tulelake Sumps at the D pump increases to 0.33 mg L1. Water leaving the Lower Klamath National Wildlife Refuge (LKNWR) sampled at the start of the Klamath Straits Drain, averaged 0.33 mg L1, similar to those at the D pump. TP increased further to 0.40 mg L"1 a the end of the Klamath Straits Drain. The overall increase in P concentration in surface waters was much less than for salt, suggesting that processes other than simple enrichment are occurring, particularly those associated with the exchange of sedimentary P and aquatic plant species. TN increases from 2.3 mg L"1 to 4.0 mg L1 over the same pathway. Atomic ratios (TN:TP) of surface water samples remain constant at approximately 10:1 throughout the system, suggesting that the amount of sediment and other small particulate matter in surface waters affects the values observed. The amount of sediment is influenced in part by the agitation of surface water as it passes through pumps and over weirs. 5. The average seasonal TP value in tile drains beneath farm fields is approximately 0.34 mg L"1 . While average total P values in subsurface tile drains were not different from those found at the D pump and the LKNWR outlet, the range in values was great (0.1 to 0.8 mg L1). Similarly, high NO3 -N values were observed at times in tile drains. Very high values in tile drains lead to the inference that some fertilizer N and P is lost in drainage water, combined with nutrients derived from decaying soil organic matter. The amount estimated as lost is much less than the amount of surplus fertilizer P applied and the amount of P surmised to be mineralized from decaying soil organic matter. P from fertilizer and decaying organic matter appears to be accumulating in soils and lake sediments in the region. 6. Ammonia N concentrations are at or below the limit of detection in subsurface agricultural tile lines and one to two orders of magnitude below the values observed in surface soils. Un ionized ammonia increases with temperature. Values above 0.25 mg L1 were observed in late summer at several locations. 7. Some leaching of soluble salts and nutrients is unavoidable when crops are irrigated. P fertilizer is applied at rates higher than crop removal, while fertilizer n is applied at rates less than crop removal. Reduced fertilizer use can help bring P inputs and outputs into balance and may reduce further any avoidable losses of P. This objective should be the subject of an agronomic research program in the region. 8. Surface waters entering the TDD, the TLNWR, and the LKNWR are already enriched with N and P. It seems unlikely that reducing N and P losses from farming in the TID, if possible, would influence surface water quality sufficiently to make them significantly less eutrophic. For P, the hypothesized threshold concentration limiting algae growth in fresh waters is 5 to 25 times smaller than the values observed in waters entering the TID for irrigation use. The addition of 1. nutrients from agriculture probably does not influence significantly surface water quality in the region. Wetland sediments, large amounts of organic matter in soils, and water introduced for irrigation contain essentially unlimited amounts of nutrients for aquatic plant growth. It is not clear how this circumstance could be changed under any reasonable time frame, if ever. 9. Using a TMDL approach may not result in reduced amounts of nutrients returned to the Klamath River because wetlands and farming practices in the southern portion of the Klamath Project result in the net removal of nutrients from the waters diverted for irrigation on a yearly basis, compared to allowing the same amount of water simply to flow down the river unused. Because of large errors of estimation for the amounts of water transferred, combined with smaller errors associated with estimating nutrient concentrations in water samples, and with year to year climate variation, TMDLs may not be an effective or efficient means of reducing nutrients in return flows to the Klamath River. Rational confidence limits for TMDLs may have to be too broad to be effective. Recycling of some drainage water for irrigation would reduce the amount of nutrients returned to the river more effectively than implementing a TMDL program. Close

• 725. [Image] Natural flow of the upper Klamath River

  	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 ...
  	Citation × Citation Citation Abstract Copy Title: Natural flow of the upper Klamath River Author: United States. Bureau of Reclamation. Klamath Basin Area Office Year: 2005, 2008 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 Title: Natural flow of the upper Klamath River Author: United States. Bureau of Reclamation. Klamath Basin Area Office Year: 2005, 2008 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 Close

• 726. [Image] Handbook for developing watershed plans to restore and protect our waters

  	Draft; Title from title screen (viewed on Mar. 17, 2006); "October 2005."; "EPA 841-B-05-005."; Includes bibliographical references
  	Citation × Citation Citation Abstract Copy Title: Handbook for developing watershed plans to restore and protect our waters Author: United States Environmental Protection Agency, Office of Water Year: 2005, 2008, 2006 Draft; Title from title screen (viewed on Mar. 17, 2006); "October 2005."; "EPA 841-B-05-005."; Includes bibliographical references Title: Handbook for developing watershed plans to restore and protect our waters Author: United States Environmental Protection Agency, Office of Water Year: 2005, 2008, 2006 Draft; Title from title screen (viewed on Mar. 17, 2006); "October 2005."; "EPA 841-B-05-005."; Includes bibliographical references Close

• 727. [Image] Upper Klamath Lake Basin nutrient-loading study: assessment of historic flows in the Williamson and Sprague Rivers

  	"The goal of the project is to quantitatively describe the nature and extent of the ground-water flow systems in the basin."
  	Citation × Citation Citation Abstract Copy Title: Upper Klamath Lake Basin nutrient-loading study: assessment of historic flows in the Williamson and Sprague Rivers Author: Risley, John C. Year: 1999, 2005, 2004 "The goal of the project is to quantitatively describe the nature and extent of the ground-water flow systems in the basin." Title: Upper Klamath Lake Basin nutrient-loading study: assessment of historic flows in the Williamson and Sprague Rivers Author: Risley, John C. Year: 1999, 2005, 2004 "The goal of the project is to quantitatively describe the nature and extent of the ground-water flow systems in the basin." Close

• 728. [Image] Klamath County, Oregon: its resources and advantages, its present and its future; a land of great pines, hardy cattle, wonderful lakes and temperate climate; its productive land needs thousands of people for its proper development

  	24 p.; ill.; Title from cover
  	Citation × Citation Citation Abstract Copy Title: Klamath County, Oregon: its resources and advantages, its present and its future; a land of great pines, hardy cattle, wonderful lakes and temperate climate; its productive land needs thousands of people for its proper development Author: Pierce, Joseph G. Year: 1900, 2006, 2005 24 p.; ill.; Title from cover Title: Klamath County, Oregon: its resources and advantages, its present and its future; a land of great pines, hardy cattle, wonderful lakes and temperate climate; its productive land needs thousands of people for its proper development Author: Pierce, Joseph G. Year: 1900, 2006, 2005 24 p.; ill.; Title from cover Close

• 729. [Image] Report on payment capacity for Tule Lake irrigation district, Klamath Project

  	SUMMARY To provide a basis for negotiations of a repayment contract with an irrigation district representing the water users of the Tule Lake Division of the Klamath Project, this report has been prepared. ...
  	Citation × Citation Citation Abstract Copy Title: Report on payment capacity for Tule Lake irrigation district, Klamath Project Author: Best, R.R. Year: 1948, 2004 SUMMARY To provide a basis for negotiations of a repayment contract with an irrigation district representing the water users of the Tule Lake Division of the Klamath Project, this report has been prepared. It covers past, present, and anticipated future agricultural and economic conditions and substantiates the proposed district's capacity to repay construction costs for irrigation water as well as to meet operation and maintenance charges It has been prepared according to procedures and policies established pursuant to the Federal Reclamation laws (Act of June 17, 1902, 32 Stat. 388, and acts amendatory thereof and supplementary thereto.) In general, a representative farm budget method of analysis was employed to determine the payment capacity* Gross income of the land was based upon average per acre yields in the area and 1939-44 prices received. Prices of certain crops were adjusted further in accordance with long term outlook for these crops. From the gross income, all farm operating and retention expenses, including cultural and harvesting costs, taxes, insurance, depreciation and replacement, interest on investment, and a reasonable allowance for family living predicated upon the same base period (1939-44) have been subtracted to arrive at payment capacity. Individual consideration has been given to the block of land entered prior to 1948 (the major portion of the area), the lands of the Coppock Bay Area which are principally Class 2, and the undeveloped lands of the area just south of Malin, Oregon, Area C, Plate 1. The annual payment capacity of the irrigable lands entered prior to 1914-8, is determined to be approximately $50 per acre. The Class 2 lands of the Coppock Bay Area are shown to have a payment capacity of $21 per acre, as a result of slightly higher operating costs and probable lower yield or quality of certain crops. For the undeveloped area just south of Malin, Area C of Plate 1, the payment capacity is determined at $18 per acre after development to the extent expected under settlement and development plans currently being formulated The weighted average payment capacity for these areas is calculated to be $26.25 per acre. There is no need for a development period for the lands of the Tule Lake Division, except for the latter area as indicated above. Furthermore, after liberal allowance for farming costs and a reasonable family living, the resulting payment capacities appear to be well in excess of any annual installments likely to be considered necessary for repayment of the District's construction obligation and operation and maintenance charges. Title: Report on payment capacity for Tule Lake irrigation district, Klamath Project Author: Best, R.R. Year: 1948, 2004 SUMMARY To provide a basis for negotiations of a repayment contract with an irrigation district representing the water users of the Tule Lake Division of the Klamath Project, this report has been prepared. It covers past, present, and anticipated future agricultural and economic conditions and substantiates the proposed district's capacity to repay construction costs for irrigation water as well as to meet operation and maintenance charges It has been prepared according to procedures and policies established pursuant to the Federal Reclamation laws (Act of June 17, 1902, 32 Stat. 388, and acts amendatory thereof and supplementary thereto.) In general, a representative farm budget method of analysis was employed to determine the payment capacity* Gross income of the land was based upon average per acre yields in the area and 1939-44 prices received. Prices of certain crops were adjusted further in accordance with long term outlook for these crops. From the gross income, all farm operating and retention expenses, including cultural and harvesting costs, taxes, insurance, depreciation and replacement, interest on investment, and a reasonable allowance for family living predicated upon the same base period (1939-44) have been subtracted to arrive at payment capacity. Individual consideration has been given to the block of land entered prior to 1948 (the major portion of the area), the lands of the Coppock Bay Area which are principally Class 2, and the undeveloped lands of the area just south of Malin, Oregon, Area C, Plate 1. The annual payment capacity of the irrigable lands entered prior to 1914-8, is determined to be approximately $50 per acre. The Class 2 lands of the Coppock Bay Area are shown to have a payment capacity of $21 per acre, as a result of slightly higher operating costs and probable lower yield or quality of certain crops. For the undeveloped area just south of Malin, Area C of Plate 1, the payment capacity is determined at $18 per acre after development to the extent expected under settlement and development plans currently being formulated The weighted average payment capacity for these areas is calculated to be $26.25 per acre. There is no need for a development period for the lands of the Tule Lake Division, except for the latter area as indicated above. Furthermore, after liberal allowance for farming costs and a reasonable family living, the resulting payment capacities appear to be well in excess of any annual installments likely to be considered necessary for repayment of the District's construction obligation and operation and maintenance charges. Close

• 730. [Image] Geology and ground-water resources of the Swan Lake-Yonna Valleys area, Klamath County, Oregon

  	Abstract The Swan Lake-Yonna Valleys area consists of two intermountain valleys with their subordinate side valleys adjoining slopes, and mountainous boundary ridges, In all the area covered is about 256 ...
  	Citation × Citation Citation Abstract Copy Title: Geology and ground-water resources of the Swan Lake-Yonna Valleys area, Klamath County, Oregon Author: Meyers, Joseph D. Year: 1952, 2007, 2005 Abstract The Swan Lake-Yonna Valleys area consists of two intermountain valleys with their subordinate side valleys adjoining slopes, and mountainous boundary ridges, In all the area covered is about 256 square miles but the essential agricultural sections are restricted to the floors of Swan Lake and Yonna valleys with their respective subsidiary extensions of Pine Flats and Alkali Lake flats, a valley-floor area totaling about 90 square miles The floors of Swan Lake Valley and Yonna Valley lie at an altitude of about U52OO feet but the mountainous boundary ridges rise generally to 6000 feeto Yonna Valley is largely drained to Lost River by Buck Creek but also in part to Alkali Lakeo Swan Lake Valley and Pine Flats have only internal drainage. The Swan Lake Valley floor is the top of a deep alluvial fill, while Yonna Valley floor is mainly an erosional surface sloping to lines of through drainage Precipitation is about lit inches annually on the valley floors 9 but must be much more, possibly 18 to 24 inches, on the higher parts of the drainage basins. The growing season is short and killing frosts do occur in late spring and early fall. The rock units forming the bedrock structure of the area are consolidated or semiconsolidated rocks of Tertiary age and are largely of volcanic-flow and volcanic-sedimentary originc They consist of three main elements, a lower lava-rock unit, a sedimentary and volcanic-sedimentary unit, and an upper lava-rock unito The unconsolidated deposits are the older alluvium of Quaternary (and in part of late-Tertiary) age and the younger alluvium of Quaternary age0 The bedrock is faulted and deformed particularly so along a northwest-southeast set of fault lines that have given a remarkable linearity to the topography. Unpublished records subject to revision Ground water occurs below a regional water table that slopes south-ward to the level of the Lost Rivero The upper lava rocks and the lower lava rocks contain the principal permeable zones that occur beneath the areao Breccia and other porous zones in those rocks in places yield water to wells at a rate as large as 35OOO gallons per minute with but 1 or 2 feet of drawdowno The economical construction of irrigation wells requires the determination of the best possible location at which those rocks may be tapped at shallow depth below the level of the water tableo The ground water in general relatively low in dissolved mineral matter and is but slightly to moderately hard and would be considered chemically satisfactory for most uaeso Irrigation is the principal use of the ground water in the area north of the Horsefly Irrigation Districto There 3? wells supplied about 6,000 acre-feet of water to about 3800 acres of land in 1950. Water-level records obtained since 19U8 and approximations of the probable annual recharge from precipitation indicate that the present withdrawals are considerably less than the annual increment of the ground-water recharge, Rough estimates indicate that an increase in withdrawals of as much as 100 percent or more can take place before ground-water levels, by a persistent lowering, will begin to indicate that the annual replenishment is being exceeded. Title: Geology and ground-water resources of the Swan Lake-Yonna Valleys area, Klamath County, Oregon Author: Meyers, Joseph D. Year: 1952, 2007, 2005 Abstract The Swan Lake-Yonna Valleys area consists of two intermountain valleys with their subordinate side valleys adjoining slopes, and mountainous boundary ridges, In all the area covered is about 256 square miles but the essential agricultural sections are restricted to the floors of Swan Lake and Yonna valleys with their respective subsidiary extensions of Pine Flats and Alkali Lake flats, a valley-floor area totaling about 90 square miles The floors of Swan Lake Valley and Yonna Valley lie at an altitude of about U52OO feet but the mountainous boundary ridges rise generally to 6000 feeto Yonna Valley is largely drained to Lost River by Buck Creek but also in part to Alkali Lakeo Swan Lake Valley and Pine Flats have only internal drainage. The Swan Lake Valley floor is the top of a deep alluvial fill, while Yonna Valley floor is mainly an erosional surface sloping to lines of through drainage Precipitation is about lit inches annually on the valley floors 9 but must be much more, possibly 18 to 24 inches, on the higher parts of the drainage basins. The growing season is short and killing frosts do occur in late spring and early fall. The rock units forming the bedrock structure of the area are consolidated or semiconsolidated rocks of Tertiary age and are largely of volcanic-flow and volcanic-sedimentary originc They consist of three main elements, a lower lava-rock unit, a sedimentary and volcanic-sedimentary unit, and an upper lava-rock unito The unconsolidated deposits are the older alluvium of Quaternary (and in part of late-Tertiary) age and the younger alluvium of Quaternary age0 The bedrock is faulted and deformed particularly so along a northwest-southeast set of fault lines that have given a remarkable linearity to the topography. Unpublished records subject to revision Ground water occurs below a regional water table that slopes south-ward to the level of the Lost Rivero The upper lava rocks and the lower lava rocks contain the principal permeable zones that occur beneath the areao Breccia and other porous zones in those rocks in places yield water to wells at a rate as large as 35OOO gallons per minute with but 1 or 2 feet of drawdowno The economical construction of irrigation wells requires the determination of the best possible location at which those rocks may be tapped at shallow depth below the level of the water tableo The ground water in general relatively low in dissolved mineral matter and is but slightly to moderately hard and would be considered chemically satisfactory for most uaeso Irrigation is the principal use of the ground water in the area north of the Horsefly Irrigation Districto There 3? wells supplied about 6,000 acre-feet of water to about 3800 acres of land in 1950. Water-level records obtained since 19U8 and approximations of the probable annual recharge from precipitation indicate that the present withdrawals are considerably less than the annual increment of the ground-water recharge, Rough estimates indicate that an increase in withdrawals of as much as 100 percent or more can take place before ground-water levels, by a persistent lowering, will begin to indicate that the annual replenishment is being exceeded. Close