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.






The Kidder Creek Watershed is located in southern Siskiyou County, California, approximately 19 miles southwest of Yreka. The principal stream of the watershed is Kidder Creek which flows easterly and outlets into Scott River approximately 1 mile southwest of the City of Fort Jones. Elevations in the watershed range from 2,700 to 7,800 feet MSL.

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.





It is estimated that 24,482 acres would flood in the Scott River Valley at the one percent chance event, including 14,715 acres due to the Scott River. Flooding in the Kidder Creek Watershed alone totals about 9,450 acres with 2,919 acres occurring on the Kidder Creek floodplain and 6,531 acres occurring on the Scott River floodplain for this event.

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.



Localized areas of sheet and gully erosion, resulting from poor vegetative cover (due to improper timber management, over grazing and wildfires), occur in the upland portions of the watershed. Streambank erosion occurs in isolated areas of the watershed and along a two mile portion of Kidder Creek below the proposed damsite. This erosion causes a loss of irrigable land and the sediment contributes pollution to Kidder Creek and Scott River.

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.



To fully realize the agricultural potential of the watershed, additional irrigation water is needed. The potentially irrigable land in the Kidder Creek Watershed totals approximately 11,580 acres. Of this, about 8,500 acres are partially irrigated and 3,080 acres will require a full supply of irrigation water. The existing supply from local creeks is inadequate and usually dries up by the end of June.

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 municipal and industrial water supplies in the proposed service area are adequate, and the estimated probable ultimate mean seasonal demand is only 400 acre-feet (California Department of Water Resource, Bulletin No. 83, Klamath River Basin Investigation, July 1964).


Between 1958 and 1980 the recreational needs of Siskiyou County are expected to increase by more than 200 percent to an estimated use of over 3 million activity-days (California Outdoor Recreation Plan Committee, California Outdoor Recreation Plan, Parts I and II, 1960). There is a need for recreational facilities for such activities as fishing, swimming, camping, hiking, horseback riding and picnicking.


According to the California Department of Fish and Game, the 800 square miles of the Scott River System, which includes Kidder Creek, supports an annual run of approximately 10,000 king salmon, 2,000 silver salmon and 20,000 to 40,000 steelhead (California Department of Water Resources, Bulletin No. 136, North Coastal Area Investigation, Appendix C, Fish and Wildlife, April 1965 by Department of Fish and Game, Water Projects Branch, Contract Services Section) The majority of king salmon spawn in the Scott River from the upper end of Scott Valley downstream to its confluence with the Klamath River. Deterioration of spawning areas by silt and sand from past mining operations covering streambed gravels appears to be a problem. Several miles of Scott River and many tributaries utilized by salmon and steelhead become dry both from natural causes and from irrigation diversions in the summer.

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.



The Kidder Creek Watershed has an average annual rainfall that ranges from 20 inches at the valley floor to 70 inches at the mountain tops. Runoff from the watershed averages about 14 inches per year and appears adequate to supply the future foreseeable needs, if the entire runoff could be utilized. Since interception and storage of the entire runoff is not feasible, irrigation water must be developed from additional sources.

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.



This project is in the Siskiyou County Soil Conservation District. The soil conservation district and Siskiyou County Board of Supervisors are interested in sponsoring watershed projects. The soil conservation district is willing and able to accelerate the needed land treatment that will be required in a watershed project. At present, local interest in a watershed project appears to be moderate pending more detailed planning information.


The California Department of Water Resources investigated the Scott Valley for both groundwater and surface water developments. Their investigations are described in Bulletin No. 83, Klamath River Basin Investigation, July 1964.

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.





Land treatment measures will be necessary to minimize upstream erosion and fully realize the benefits from the structural works of improvement. Some streambank protection at critical locations will be needed to minimize bank erosion and protect irrigable cropland. The installationid of irrigation systems and some land leveling will be necessary to prepare the land for proper irrigation. Some on-farm irrigation systems will need rehabilitation and a follow-up practice of irrigation water management will be needed to insure efficient use of water and fertilizer, minimize crop production problems, and reduce the need for supplemental drainage practices. Subsurface drainage may be necessary in some areas. Proper pasture use will be needed for improved forage production and mosquito abatement with the impending, irrigated land use. Costs for these measures have been subtracted from the gross benefits as associated costs necessary for land improvement.

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.



A multipurpose flood prevention-irrigation-recreation storage structure is proposed on Kidder Creek approximately 4.3 miles upstream of its confluence with Patterson Creek. An earthfill dam approximately 50 feet high will provide 5,000 acre-feet of beneficial-use storage allocated to the following: irrigation storage - 4,000 acre-feet (including 3,500 acre-feet used jointly for flood prevention), and recreation storage - 1,000 acre-feet. An additional 800 acre-feet of storage capacity is required for the 100-year sediment accumulation. The earthfill volume required for the dam would be approximately 1,350,000 cubic yards.

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.



Cost estimates for the multipurpose storage structure are based on data developed from USGS quadrangle maps and from recent Public Law 566 Work Plans in California. With the use of quadrangle maps, reservoir storage and earthfill volumes were plotted as a function of water surface elevation. From recent Public Law 566 Work Plans, unit costs were developed and include all construction costs for placing the fill and providing the necessary outlet works.

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.



Under present conditions, Kidder Creek will inundate 2,919 acres along its own floodplain (above the Scott River floodplain) from a one percent chance event and 2,550 acres from a 10 percent chance event With the project installed, complete flood Protection is provided at the ten percent chance event. The effect of this project on the Scott River will be to reduce flooding by 54 acres for the one percent chance event and 196 acres for the 10 percent chance event.

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.



A flood control plan for the entire Scott Valley area should be investigated in greater detail. At the present time, there are four other watersheds in Scott Valley--Etna, Kidder and Moffett Creeks, and East Fork Scott River--that are under preliminary investigation as potential PL 566 projects. Channel improvement on the main stem Scott River was investigated briefly with the assumption that five multipurpose dams, controlling 30 percent of the drainage area and having a combined flood control storage of 17,500 acre-feet, would be installed. Complete flood protection could be provided at the 10 percent chance event with a reduction in flooding of 9,600 acres on the main stem Scott River due to channel improvements alone. (Flooding from Scott River in the Kidder Creek Watershed would be reduced by 4,460 acres for the 10 percent chance event.) Five dams, including Kidder Creek Dam, would reduce flooding by 5,300 acres on the tributaries and 2,000 acres on the main stem Scott River. Capital cost of channel improvement on Scott River was estimated at $2,102,000 with an annual cost of $138,100. Channel improvement appears economically justified.

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
Item  Damage (Dollars) 
Floodwater  Kidder Creek  Scott River  Totals
Crop and Pasture  16,200  41,300  57,500
Other Agricultural  4,400  11,300  15,700
Sediment  5,100  13,100  18,200
Road, Bridge and Channel  26,400  7,300  33,700
Urban  700  700
Indirect  9,400  8,400  17,800
Total  62,200  81,400  143,600

Table 2. Structural Data, Kidder Creek Watershed, Klamath River Basin
Dam Site  C
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
Pipelines  7 miles
Turnouts  105 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
26.6  800  1,000  3,500  5800

Table 4. Estimated Structural Cost (price base 1970), Kidder Creek Watershed, Klamath River Basin
Amount Planned  Estimated Total Cost in Dollars 
Structural Measures 
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
Engineering Services  1,334,000
Land Rights  578,000
Project Administration  85,000
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
Multipurpose Reservoir 
Flood Prevention  1,366,000  314,000  94,000  26,000  1,800,000
Agricultural Water  1,211,000  279,000  81,000  23,000  1,594,000
Recreation Storage  528,000  121,000  273,000  10,000  932,000
Sub totals  3,105,000  714,000  448,000  59,000  4,326,000
Irrigation Pumping Plants  124,000  29,000  1,000  154,000
Irrigation Wells  248,000  57,000  8,000  2,000  315,000
Irrigation Distribution System  2,131,000  490,000  111,000  21,000  2,753,000
Channel Improvement  59,000  14,000  7,000  600  80,600
Fish and Deer Mitigation Measures  56,000  13,000  500  69,500
Basic Recreation Facilities  76,000  17,000  4,000  900  97,900
Totals  5,799,000  1,334,000  578,000  85,000  7,796,000

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
Multipurpose Reservoir  233,800  11,200  245,000
Irrigation Pumping Plants  8,300  21,200  29,500
Irrigation Wells  17,000  5,200  22,200
Irrigation Distribution System  148,800  19,200  168,000
Channel Improvement  4,400  2,200  6,600
Fish and Deer Mitigation Measures  3,700  2,900  6,600
Basic Recreation Facilities  5,300  9,200  14,500
Totals  421,300  71,100  492,400

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
Totals  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 
Flood Prevention  1,911,000  1,783,000  128,000
Irrigation  4,843,000  2,541,000  2,302,000
Recreation  1,042,000  548,000  494,000
TOTALS  7,796,000  4,872,000  2,924,000