Prepared under Authority of Section 6, Public Law 83-566 (as amended) by the Soil Conservation Service and Forest Service representatives on the U.S. Department of Agriculture, River Basin Planning Staff, Berkeley, California.
Greenview is the only notable town in the watershed. The watershed area is bordered on the west by the Salmon Mountains and on the east by Scott River. State Highway 3 runs north through the service area towards Fort Jones and intersects Interstate Highway 5 near Yreka.
The economy of the Kidder Creek watershed is based primarily on lumbering and livestock enterprises. This general area is also important for salmon and steelhead fisheries. The popular game species are deer and quail.
The drainage area of the watershed is approximately 50,144 acres and the irrigable area of Kidder Creek Watershed totals about 11,580 acres. Present land use in the watershed is estimated as follows: 68 percent forest, brush and woodland; 22 percent cropland; 9 percent range; 1 percent urban, channels, roads, and miscellaneous uses.
The 1964 U.S. Census of Agriculture indicates that the average farm size in Siskiyou County decreased slightly 0.8 percent) from 1,401 acres to 1,390 acres since the previous agricultural census in 1959. The 1964 value of land and buildings for the average farm was $132,105, or $95 per acre. This represents an increase in value per acre of 58 percent over a fiveyear period. Specific data for the Kidder Creek Watershed portion of Siskiyou County was not available.
Soils in the irrigable area of the Kidder Creek Watershed are represented by the Stoner and Serpa soil series, which are in land capability classes II and III respectively. These soils are over 60 inches deep, have a slight to moderate erosion hazard, occur on O to 9 percent slopes and have moderately slow to slow permeabilities. Stoner soils have gravelly loam surface textures, gravelly clay loam subsoils and good drainage. Serpa soils have silty clay loam surface textures, silty clay subsoils and poor drainage.
Dominant soil series of the uplands are Kinkel and Boomer. Soil depths range from 20 to 60 inches over bedrock, drainage is good and permeability moderately slow. Slopes vary from 15 to 50 percent and the erosion hazard is moderate to high.
More detailed soils information is available at the Soil Conservation Service office in Yreka.
To reduce Scott River flooding, it is necessary to control major tributaries such as Kidder Creek. The average annual damage on the Kidder Creek floodplain alone is $62,200, and consists primarily of crop and pasture, road, bridge, and existing channel improvement damages. Downstream damages on the Scott River, which are affected by Kidder Creek flood flows, are primarily to crops and pasture. See TABLE I for detailed information.
It is estimated the average sediment yield would be 0.3 acre-feet per year for each square mile of watershed or a total for the watershed of 23.5 acrefeet per year.
Preliminary estimates for improved pasture, alfalfa and potatoes show a seasonal consumptive use of 28, 27, and 22 inches respectively. Of this amount, seasonal precipitation supplies 1 to 7 inches leaving a net irrigation water requirement of 21 inches each for improved pasture, alfalfa and potatoes. Assuming a field efficiency of 70 percent and an overall canal evaporation and conveyance loss of 20 percent, the gross irrigation demand is 2.9 acre-feet per acre.
Soils information for the area indicates that drainage is presently a problem and that it will increase under full irrigation. Present USDA programs should be adequate to solve drainage problems. The proposed irrigation distribution system would also reduce the drainage problem by minimizing seepage losses, which presently occur from existing irrigation canals. Better drainage realized by installing flood control and land treatment measures should also reduce the mosquito problem.
Present wildlife populations are limited, but the situation can be improved through better watershed management. The valley area and the lower slopes around the valley are important winter ranges for migratory deer and the deer population is generally greater than the available forage can support. Deer populations should be kept at a level commensurate with the carrying capacity of the range. This will maintain a healthier herd, protect the soil resource, and probably sustain a greater animal harvest and more hunting days per year.
A preliminary geologic investigation shows that a favorable dam and reservoir site exists on Kidder Creek approximately 4.3 miles upstream of its confluence with Patterson Creek. The drainage area at the site is 26.6 square miles with an average annual precipitation of 48 inches. The mean annual runoff is 33,300 acre-feet with a firm yield (80 percent chance) of 24,440 acrefeet.
A floodwater-retarding structure on Kidder Creek would control runoff from 26.6 square miles (48 percent) of the Kidder Creek drainage. This structure would protect the agricultural area immediately downstream and provide complete protection for the 10 percent chance event on 2,550 acres in the Kidder Creek floodplain.
Developing the underground water supply is also a means of meeting future demands for water. The estimated groundwater storage capacity of the entire Scott Valley is 400,000 acre-feet (United States Department of the Interior, Geological Survey, Water Supply Paper 1462, Geology and Groundwater Features of Scott Valley, Siskiyou County, California, 1958). Some existing wells in Scott Valley produce from 1,200 to 2,500 gallons per minute at depths of 75 to 120 feet. Assuming an average saturated thickness of 100 feet and an average specific yield of 15 percent, a 2,275-acre area could supply the total irrigation need of 34,100 acre-feet.
Opportunities for satisfying some of the recreational needs of the county with the proposed reservoir are good. The sides will be easily accessible and on gentle slopes ideal for camping, swimming, fishing, hiking, horseback riding and picnicking facilities.
Water quality of both ground and surface water is excellent for most beneficial purposes.
The proposed water development will inundate a small portion of winter range used by migratory deer. This loss can be mitigated by improving rangeland and bottom land adjacent to the reservoir area.
To mitigate loss of fish habitat from constructing the dam, adult salmon and/or steelhead would be trapped below the dam and released above the dam to spawn. Traps will also be placed above the reservoir to catch the young fingerlings, so they can be released downstream of the dam. An alternative would be to trap the adult fish below the dam for transportation to a nearby hatchery to spawn, and subsequent release of fingerlings below the dam. To insure the success of the mitigation measures, a plan of operation must be implemented before construction, for scheduling sufficient release rates to provide for fish passage.
Water quality of both ground and surface water is excellent for most beneficial purposes.
Present fire protection facilities are adequate. However, temporary improvements and precautionary measures will be necessary during the construction period. Fire breaks and other fire protection facilities will be needed as recreation activities expand. Storage assigned to recreation and irrigation could be used for fire fighting in case of emergency.
A "Report on Comprehensive Planning Study" was prepared in March 1967 by McCreary-Koretsky Engineers. The report contains information on the Scott Valley area, problems of interest in comprehensive planning, a program for development, and recommendations for its implementation.
The San Francisco District of the Corps of Engineers has also conducted a preliminary study on a large dam and reservoir site near Callahan.
Fencing of gullied and eroded areas and sound timber management will help to control erosion and the resulting improvement in vegetative cover will enhance wildlife habitat. A planned program of brush manipulation (including browse propagation and regeneration), reforestation, proper grazing and wildlife management, timber stand improvement, browse propagation and browse regeneration on suitable soils will improve wildlife habitat, range forage, and timber production as well as reduce the fire hazard.
The danger of wildfires in the area requires that the present level of fire protection be maintained to protect the proposed land treatment measures.
For the 10 percent chance event, this dam will eliminate flooding on the estimated 2,550-acre Kidder Creek floodplain and would also reduce flooding in the 11,581-acre Scott River floodplain by 196 acres.
About 7,395 acres of irrigable land above the 10 percent floodplain would have an estimated 19 miles of concrete-lined canals to distribute the irrigation water. Another 4,185 acres within the 10 percent floodplain would also be irrigated, but the distribution system would consist of about 7 miles of buried pipeline to minimize flood damage to the system. Turnouts would be provided for an estimated 105 farms in the service area.
The permanent recreation pool will have 145 acres of surface area and a depth of 9 feet above the sediment pool. This pool will extend about 0.8 mile along Kidder Creek and provide two miles of shoreline.
To utilize the full recreational potential of the reservoir, several basic facilities are proposed. These facilities include 5 developed camp sites, 4 developed picnic sites, a swimming beach, one boat launching ramp and dock, necessary sanitation, adequate access roads, and parking.
To supplement the irrigation releases from the reservoir, wells and pumping plants would be located throughout the service area. Based on existing wells in the area, the average well capacity would be approximately 1,000 gallons per minute and have a depth of 100 feet. Each pump will have a maximum capacity of 1,000 gallons per minute and the water would be pumped into the same distribution system proposed for the irrigation releases from the dam.
To provide protection from flooding on the land adjacent to Kidder Creek, it will be necessary to excavate a channel from the proposed dam to State Highway No. 3. The spoil will be used to construct levees on each side of the channel and there will be drains provided so the surface water will drain into the channel. Tchannel will be vegetated and 1,000 feet will have rock rip rap to minimize erosion.
See TABLES II, III and IV for detailed information.
The sediment storage requirements were based upon information gathered during the North Coastal River Basin Survey (Type IV) in the Klamath River Basin. Flood prevention storage requirements were determined by using procedures outlined in SCS Technical Release No. 10 and a regional stream study for the Klamath River Basin. The effects of the proposed structure on the main stem Scott River floodplain were determined by a computer study. The computer programs (water surface profiles and hydrology TR-20) were used to evaluate the effects of several dams including Kidder Creek Dam within the Scott River drainage. Procedures outlined in SCS Technical Release No. 21 were used to estimate the net irrigation requirements.
Unit prices for pumping plants, irrigation pipelines, concrete-lined canals, wells, and channel improvement are similar to those used for Public Law 566 watershed planning.
Costs for engineering services were estimated to be 23 percent of the total construction cost.
Land rights were based on estimates secured from local SCS personnel. Costs for relocation of utilities were developed from existing PL 566 Work Plans and are based on a percentage of the construction cost of the distribution system. Unit prices for road relocation are based upon a recent cost study by the SCS State Office Design Unit.
Operation and maintenance costs for the Kidder Creek Dam and distribution system are based on factors developed in California and used in PL 566 watershed planning. An annual lump sum was included to cover maintenance personnel and equipment and secretarial help.
See TABLES V, VI and VII for detailed information.
Average annual flood damage reduction benefits occurring primarily to agricultural crops, roads, bridges and sediment in the floodplain total $49,200 annually. In addition, $99, 800 of agricultural more intensive use benefits were allocated to flood prevention and included in Table VII.
The availability of irrigation water and protection from flooding will enable farm operators to increase their net income on 11,580 acres of farmland. The difference in net income with and without the project, less the associated costs of irrigation, allowing for a 5-year straight-line lag in accrual, equals $454,800 annually. (Benefits allocated to irrigation only.)
Recreation benefits accruing to the 145-acre recreation pool at the multiple-purpose reservoir will amount to $49,300 annually, assuming a 5-year straight-line delay in accrual and a recreation-day value of $1.50. An annual total of 36,250 visitor days was the estimated full use at this site.
Secondary benefits were estimated to be ten percent of primary flood prevention, recreation and irrigation benefits. These secondary benefits total $65,300 annually and were local in nature. Secondary benefits from a national viewpoint were not considered.
The benefit-cost ratio is 1.5:1.0 for the overall project. A summary of benefits and cost is given in Table VII.
If the valley is planned as one unit, additional storage and releases should be considered at all potential reservoirs for fisheries enhancement.
Table 1. Estimated Average Annual Flood Damage (in adjusted normalized prices), Kidder Creek Watershed, Klamath River Basin
|Floodwater||Kidder Creek||Scott River||Totals|
|Crop and Pasture||16,200||41,300||57,500|
|Road, Bridge and Channel||26,400||7,300||33,700|
Table 2. Structural Data, Kidder Creek Watershed, Klamath River Basin
|Drainage Area||26.6 square miles|
|Estimated Height of Dam||50 feet|
|Estimated Volume of Fill||1,350,000 cubic yards|
|Emergency Spillway Type||concrete|
|Maximum Surface Area Emergency Spillway Level||260 acres|
|Multipurpose Dam||1 each|
|Fish Traps||2 each|
|Irrigation Pumping Plants (20 h.p., 1000 g.p.m. discharge)||54 each|
|Irrigation Wells||54 each|
|Channel Improvement||2 miles|
Table 3. Planned Reservoir Storage Capacity (in acre feet), Kidder Creek Watershed, Klamath River Basin
|Reservoir site||Drainage Area
in sq miles
|Sediment Storage||Recreation Storage||Flood Prevention and Irrigation||Total|
Table 4. Estimated Structural Cost (price base 1970), Kidder Creek Watershed, Klamath River Basin
|Amount Planned||Estimated Total Cost in Dollars|
|Multipurpose dam||1 each||3,105,000|
|Irrigation Pumping Plants||54 each||124,000|
|Irrigation Wells||54 each||248,000|
|Irrigation Distribution System||Lump sum||2,131,000|
|Channel Improvement||2.0 miles||59,000|
|Fish & Deer Mitigation Measures||Lump sum||56,000|
|Basic Recreation Facilities||Lump sum||76,000|
|Sub total construction||5,799,000|
|Total Structural Measures||7,796,000|
Table 5. Distribution of Structural Cost - Kidder Creek Watershed, Klamath River Basin. Installation Cost in Dollars (price base 1970)
|Installation Cost (1970 price base dollars)|
|Construc-tion||Engineering Services||Land Rights||Project Admin.||Installation Costs|
|Irrigation Pumping Plants||124,000||29,000||0||1,000||154,000|
|Irrigation Distribution System||2,131,000||490,000||111,000||21,000||2,753,000|
|Fish and Deer Mitigation Measures||56,000||13,000||0||500||69,500|
|Basic Recreation Facilities||76,000||17,000||4,000||900||97,900|
Table 6. Annual Cost Kidder Creek Watershed, Klamath River Basin (Price base, 1970 dollars. Installation Costs; Adjusted Normalized Prices - OM&R Costs. 100 year evaluation period, 5-3/8% interest).
|Item||Amortizaiton of Installlation Cost||Operation, Maintenance and Replacement Cost||Total|
|Irrigation Pumping Plants||8,300||21,200||29,500|
|Irrigation Distribution System||148,800||19,200||168,000|
|Fish and Deer Mitigation Measures||3,700||2,900||6,600|
|Basic Recreation Facilities||5,300||9,200||14,500|
Table 7. Comparison of Benefits and Costs for Structural Measures - Kidder Creek Watershed, Klamath River Basin in Dollars (Price base - Construction Cost 1970; Benefits, O&M - Adjusted Normalized Prices)
|Average Annual Benefit|
|Unit||Damage Reduction||Irrigation||Recreation||Secondary||Total||Average Annual Cost||Benefit Cost Ratio|
|Multipurpose Reservoir, Irrigation and Recreation Facilities||149,000||454,000||49,300||65,300||718,400||492,400||1.5:1|
Table 8. Cost Allocation And Cost Sharing Summary, Kidder Creek Watershed Watershed, Klamath River Basin,Dollars in a 1970 Price Base.
|Cost-Allocation||Cost - Sharing|