Mountain Resource Group

The following report was submitted by a member of the team participating in the Pre-Harvest Inspection process related to SJWC's logging plan (NTMP) application.  It presents some very disturbing findings related to SJWC.

Residents should read this report completely, despite its length.  This is valuable information.

 

September 4, 2006
Richard Sampson
Review Team Chair
California Department of Forestry

Felton, CA

Re: 1-06NTMP-012SCL

Mr. Sampson:

I represented Aldercroft Heights County Water District on the PHI for the San Jose Water Company NTMP. Chemeketa Park Mutual Water Company also has contracted me to prepare comments on the San Jose Water Company NTMP.

I was the Hydrologist for the Mendocino County Water Agency (MCWA) from May 1989 to November 1994. The Mendocino County Board of Supervisors appointed me as their representative on pre-harvest inspections for THPs with the potential to impact public water systems. As the MCWA Hydrologist, I also reviewed Proof-of-Water pump tests for the Town of Mendocino. I also routinely reviewed CEQA documents for projects before the Planning Commission. I have a Masters in Physical Science specializing in Hydrology from ChicoStateUniversity. Since 1994 I have been a consulting Hydrologist. I have also taught Hydrology at CaliforniaStateUniversity, MontereyBay.

First I make some general observations and recommendations. Then my notes from the PHI are presented. Mitigation specific recommendations are presented in the PHI notes. Photos are available upon request.

Erosion Hazard Rating

Technical Rule Addendum No. 1, Procedure for Estimating Surface Soil Erosion Hazard Rating, Revised February 1, 1990 states that a loam underlain by a clay loam should be considered to have a restrictive layer at the top of the clay loam.

The Soil Survey of Eastern Santa Clara County, page 16, describes the Felton Soil series as:

In a representative profile, the surface layer is brown, medium acid silt loam about 2 inches thick. The sub-soil is brown, light-brown, and light yelllowish-brown, medium acid and strongly acid clay loam about 37 inches thick. The substratum is light yellowish-brown, strongly acid, shaly clay loam about 9 inches thick over interbedded shale and sandstone. (Emphasis added)

The above description from the Soil Survey shows that there is a restrictive layer at 2 inches below the surface. Such a shallow restrictive layer should get a rating of 15 for the Depth to Restrictive Layer or Bedrock on the Erosion Hazard Rating Worksheet instead of the 2 assigned by the RPF. The rating of 15 should apply to all of the Felton soils within the plan boundary, that is, the rating of 15 should be applied to Soil A, B, C, D, F, G, H and K on the worksheet.

The Felton soil series should be assigned a permeability rating of 4 since only the top two inches of the profile is silt loam which is underlain by clay loam and since the 2-year, 1-hour rainfall intensity is Extreme. In addition, the PHI found that soil piping was widespread.

The following table shows the HER score and rating after adjusting increasing the Depth to Restrictive layer by 13 points and increasing the Permeability score by 1for the Felton series soils:

NTMP EHR Map Unit

Soil Name

NTMP Units

Adjusted EHR Score

Adjusted EHR Rating

A

Felton Silt Loam 20-50%

1, 2, 5, 6, and 7

75

High

B

Felton Silt Loam 50-70%

1, 2, and 7

76

Extreme

C

Felton Silt Loam 20-50%

1, 3, 4, 5, and 7

74

High

D

Felton Silt Loam 50-70%

1, 3, 4, 5, 6, and 7

76

Extreme

E

Maymen Fine Sandy Loam 30-45%

5

55

Moderate

F

Felton Silt Loam 50-70%

8

86

Extreme

G

Felton Silt Loam 25-50%

8

79

Extreme

H

Felton Silt Loam 20-50%

Briggs Creek

80

Extreme

I

Maymen Fine Sandy Loam 25-50%

Austrian Gulch

55

Moderate

J

Maymen Fine Sandy Loam 50-70%

Austrian Gulch

55

Moderate

K

Felton Silt Loam 20-65%

Briggs Creek

83

Extreme

 

The above adjustments to the EHR result in an adjusted rating of Extreme for NTMP map Units B, D, F, G, H and K of Felton Silt Loam. This is a water quality concern since tractor operations are proposed in Units 1-7 on Felton Silt Loam 50%-70% soils in NTMP map units B and D. The soils with an adjusted EHR of Extreme in NTMP map units F, G, H and K are in cable or helicopter yarding units. Note that an EHR score of 75 is on the border between High and Extreme.

The above adjustments to the EHR result in an adjusted rating of High for NTMP map Units A, C, and G of Felton Silt Loam. The above adjustments to the EHR result in only the Maymen soils having an EHR rating of Moderate.

One result of the change of NTMP HER mapping units A, C and G from Moderate to High is that Mitigation Points M5-1 and M8-1 should be added back to the plan. First Review Team Question 6 to the RPF noted that M5-1 and M8-1 were mentioned in the text on page 60 of the NTMP but were not discussed in Section II of the NTMP. The RPF’s response was that M5-1 and M8-1 were skid trails traversing short stretches of slope between 50% and 65% with an EHR of Moderate. The above adjustments to the EHR change the rating of mapping Units A, C and G from Moderate to High. Therefore, M5-1 and M8-1 are mitigations for skid trails on slopes greater than 50% with an EHR of High. 

General Recommendation 1:

To protect water quality, all erosion control measures should assume that the EHR is Extreme.

General Recommendation 2:

Reorganize NTMP plan by operation Units. The section of the plan for each Unit should have the Unit map, description of all mitigation point, projected time of first entry, and number of acres of each stand type in the unit, number of acres in each yarding method, description of and Special Treatment Zones. Alternatively, provide a cross reference table that identifies all mitigations by unit and by type. The cross reference table should also give the page the mitigation is discussed in the NTMP and the map page showing the mitigation point.

General Recommendation 3:

Special Treatment Zones (STZ) apply to the first entry only. The NTMP is taking an adaptive management approach to adjust constraints. However, there is no language specifically stating that revised specifications for STZ should provided better or equal water quality protection than the original prescription.

Language guaranteeing equal or better water quality protection for all changes/modifications/amendments to the NTMP should be included in the Plan.

General Recommendation 4:

The Road Maintenance Program, page 23 of the NTMP, must be expanded to cover all roads on the San Jose Water Company property in the Los Gatos Creek watershed. The existing road system needs to be improved to protect water quality.

San Jose Water NTMP, PHI Notes, 8/15/2006 and 8/16/2006

Met at the parking lot near the Bear Creek Road exit at 8:30 AM. Drove through ChemeketaPark to the playground area above the slide in Unit 7. Left cars at Landing 13, the primary helicopter service landing at the site of the Austrian Dam Cement Plant near LakeElsman.

August 15, 2006

Stop-1: Mitigation point M1-2 mapped on page 42.2 and described on page 30. A new section of road is proposed within the WLPZ. Waterbars every 50 feet with outflow of waterbars directed to stable ground. All fill within 25 feet of the watercourse will be seeded and straw mulched. See Section III for further explanation and justification. See photos 2950 M1-2 and, 2951 M1-2.

The length of road segment in WLPZ is not given in the plan. Recommend that the road be kept as far from the watercourse as possible and that no sidecast be placed on the downslope side of the road.

Stop-2: M5-2. New drainage facility crossing draw. Point not in Plan.

RPF proposed using multiple 4” culverts with 5 feet of fill. The site is just a few feet upslope from the Class II WLPZ. The slope of the draw is nearly flat. It was suggested that using 18” culvert would allow for debris. The area is within the Lexington Fire (1985?). Maps of Lexington Fire are in the Fire Hazard Assessment.

Stop 3, Landing 15.

Relatively flat, brush covered area.

Stop-4, R4-2: Class-II Crossing

Discussion of whether to use 4’ arch culvert or bridge. Also discussed whether to remove crossing prior to winter or make it permanent. Dave Hope, RWQCB, just wants to know what is in the Plan. He does not think that the PHI should attempt to fix the mitigations.

Photos 2952 R4-2 to 2956 R4-2. 

Stop 5, M23-2, Bench-cut road.

Reconstruct road on scarp bench. Widen road to a full bench and end-haul. Spoils are to be placed on slopes less than 30% in 12-inch lifts. Propose to clean road of cut-face ravel by end-hauling. Michael Huyette, CGS, wants them to make sure that the subsurface is okay by having CGS inspection during actual construction. See page 21 of Plan.

Photo 2959 shows spalling of the existing road bench where groundwater seeps from the roadbed. The spalling is located near a small swale that may be providing a portion of the groundwater. The presence of the groundwater seep on the side of the road bench indicates that saturated conditions may occur near the road surface during winter, spring and potentially early summer. Recommend that subsurface drainage facilities be provided.

Downslope end of road crosses a flat area. As the road approaches the flat it is crossed by a Class-III which apparently resulted from the same stream diversion that created the erosion in Morrill Road, map point G-11. This human-caused Class-III does not appear to be mapped at the crossing of the road being constructed under M23-2.

Stop 6, Large flat on reconstructed road near Mitigation Point M17-2.

Class-III crosses the road that is to be reconstructed where the road leaves the large flat area. The Class-III is not shown on the on the map. The Class-III (photos 2961, 2962) is apparently man-made and resulted from the same diversion that exposed the PG&E line in Morrill Road. The unmapped Class-III runs from just north of R3-1 to about M17-2, see map on page 42.2. Point M17-2 is discussed on page 21. 

Stop 7, M24-2, Bench-cut road.

Full bench road construction in the WLPZ of Los Gatos Creek, see page 21 of the Plan and page 23 of the Geology Report (page 300 of Plan) for a description. Photo 2971 shows where groundwater is seeping out of steep slope, above the site where 2 feet of fill is proposed to be placed on the existing road surface to reduce the slope of the bench cut. The fill would be placed near the lower right-hand corner of photo 2972.

Stop 8: M2-2 Rolling Dip at Sag Pond.

Pages 30 and page 62 of the Plan describes the mitigation point as a section of new road across the outlet of the sag pond. The entrance to a large soil pipe was observed on the north bank of the sag pond, in line with the main pond outlet. There is the potential that the soil pipe runs directly under the pond outlet and that construction of or equipment traffic across the proposed rocked rolling dip will crush the pipe and result in routing groundwater flow to the surface. Photos 2973-2976 show potential exits of soil pipes on face exposed by fallen tree along the path of the defined outflow from the sag pond.

The entrance to another large soil pipe was observed on the north bank of the sag pond roughly 60 feet to the west (photos 2977, 2978). There appeared to be faint signs of outflow from the pond across the alignment of the proposed road. The area appeared to be at a higher elevation than the well defined outlet at M2-2. However, there may be soil pipes crossing under the proposed road alignment.

Recommend that a bridge be used to cross the defined outlet of the sag pond at M2-2. Also recommend further investigation of near-surface soil pipes that may be draining the sag pond during high water. 

Stop 9: Landing 18.

A general discussion of the NTMP was held at the site of Landing 18. The discussion touched on the widespread occurrence of soil pipes in the plan area. Besides the soil pipes at the sag pond, Dave Hope, RWQCB, said that he observed soil piping at Landing 17, see map on page 42.2. I observed soil pipes in the Austrian Gulch Helicopter Unit and in the Sample Marking Area of Unit 1 on August 16.

Tom Spittler, CDF, wants the plan to address soil pipes. Suggested that skid trails be minimized to reduce risk of collapsing soil pipes. Dave Hope, RWQCB, does not think that Tim Best, Engineering Geologist, focus on water-bar spacing is an adequate response to soil pipes.

The discussion also touched on the responsibility of San Jose Water Company for a road maintenance program for their entire property and on Big Creek’s responsibility for roads within the NTMP.

Stop 10: A Class-III with two channels.

The Class-III to the west of Landing 18 appears to have shifted its channel to the west. The eastern channel bed appears higher and there are no exposed gravels. In places the channel wall separating the two channels is very thin. Camera failure produced unusable photos. The NTMP map indicates that the Class-III with the parallel channels starts in the sag pond upslope from crossing S2-2.

Stop 11: Crossing S2-2.

Page 29 of the Plan calls skidding across the Class-III watercourse “as-is” if it is dry at the time of operations. About 30 feet upstream of the proposed skid trail crossing I noticed patches of salt-encrusted soils indicating that groundwater is relatively close to the surface (photo 3159). The soil at the crossing may be saturated in July and potentially into August. Care must be exercised that skidding operations do not occur when the soil in the crossing is saturated.

The map of Unit 2 on page 42.2 shows that the Class-III starts at S2-2. Field observations show that the Class-III extends up to at least the sag pond (photos 3160 and 3161) by the paved road. The missing segment of the Class-III above S2-2 must be mapped. 

Stop 12: Sag Pond upslope of S2-2.

Photos 3160-3161 show that the sag pond drains and that the soil is saturated and only a few puddles of standing water were present. Drainage from the road appears to contribute to the unmapped segment of the Class-III that flows down to crossing S2-2.

The map shows a utility line runs up the swale to the north of the pond.

Stop 12: Landing 19.

Landing 19 is on the edge of a deeply incised Class-II, approximately 80’ to 100’ deep. The map indicates that the deeply incised Class-II (Geologic Mitigation Point G4-3) and the WLPZ of the deeply incised Class-II is completely contained in Unit 3. Does this mean that any trees harvested from the eastern bank of the WLPZ of the deeply incised Class-II will be cabled over to the west bank of the Class-II? Does the mapping indicate that no trees will be harvested from the eastern bank of the Class-II during the tractor yarding operations in Unit 2? Will the harvest of Unit 3 involve any operations from the east bank of the Class-II? Will the STZ and WLPZ of the Class-II be subject to entry during the harvest of Unit 3 and Unit 2?

Photos 3162-3164 are looking west into the deeply incised Class-II from the approximate location of Landing 19. Photo 3165 is looking from the top of the inner gorge towards Landing 19.

Geologic Mitigation G4.

In Item 26, WLPZ and Domestic Water Protection Measures, of the NTMP (page 27) specifies that a Special Treatment Zone (STZ) will be established along the top of the inner gorge where the slope gradient is greater than 60%. Harvesting within the STZs is proposed to be restricted to redwoods growing in groups. Page 27 of the NTMP states that:

·         Special Treatment Zones (STZ) shall be flagged along the top of the inner gorge where slope gradients exceed 60%. At present the WLPZ has been expanded to encompass the STZ.

·         Within the STZ,

o        Harvest shall be restricted to redwoods in groups retaining 2/3 of the trees in the group greater than 12-inches dbh.

o        Harvesting shall exclude Douglas-fir and individual redwoods, except those incidentally damaged during operations.

o        Minor modifications to level of retention may be made to facilitate operations or regeneration based on site specific review by the project Engineering Geologist.

Discussion:

Harvesting trees within the Inner Gorge STZ unnecessarily jeopardizes water quality. The NTMP states (p. 27) that, “Harvesting on the steep valley walls could contribute to a higher incidence of shallow landslides through reduced root reinforcement.” The proposed method of limiting harvest to groups of redwoods is experimental. There are significant problems with the proposed protocol to harvest within the Inner Gorge STZ.

o        The NTMP does not define “redwoods in groups”. Big Creek Foresters stated that “groups” were redwoods within 10 feet of each other. This definition does not appear in the NTMP and so has no legal standing. Furthermore, nothing was said about the minimum number of trees required for a “group”. Logically, a group has to be three or more trees since the protocol calls for, “retaining 2/3 of the trees in the group greater than 12” dbh.” 

o        There is no way of knowing if root systems of a specific “group” of redwoods are actually interconnected. If the roots systems of the redwood trees in a “group” are not actually interconnected, then cutting the trees may have the same effect of cutting single trees.

o        Even if it could be demonstrated that the root network of redwood trees in a “group” were actually interconnected, the potential loss in root strength over time may result in the initiation of shallow landsliding. The proposed harvest protocol calls for, “… retaining 2/3 of the trees in the group greater than 12-inches dbh.” It is likely that the 1/3 of the trees harvested will be the largest trees and may account for more than 1/3 of the foliage. The resulting loss of food production may cause a die back in the root system. Loss of vigor in the root system may lead to a reduction in root reinforcement sufficient to allow initiation of shallow landsliding at some future date. Slides associated with the reduction in root strength typically occur 10 to 15 years after harvest.

o        There is no way of knowing if even a small loss of root reinforcement would be sufficient to result in the initiation of a shallow landslide at some future date. Any shallow landslide within the Inner Gorge should be considered to have a sediment-delivery-ration of 100%.

o        San Jose Water Company, Santa Clara Valley Water District, Chemeketa Park Mutual Water Company, and Aldercroft Heights County Water District all draw water from Los Gatos Creek for municipal or domestic water supply. Therefore, if there is any question of whether proposed harvest operations, under the NTMP, pose a risk to water quality, the proposed harvest methodology should be changed to ensure that no threat to water quality will occur as the result of the harvest.

o        The NTMP and Geologist Report have not demonstrated that the proposed harvesting within the Inner Gorge STZ (G4) has a zero risk to water quality.

o        The proposed protocol for the Inner Gorge STZ allows for “minor modifications to the level of retention to facilitate operations or regeneration.” The most protective measure is to prohibit harvest within the STZs established under Geologic Mitigation G4. The entire proposed harvest protocol is experimental and the definition of “minor modifications” is subject to dispute.

Recommendations:

Harvesting within the Inner Gorge areas of the NTMP should be prohibited. Protection of water quality should outweigh the economic value of harvesting the relatively few trees that would be removed under the proposed STZ for Inner Gorges.

Stop 13:M10-2. Skid Trail within Class-II WLPZ

Page 30 of the NTMP describes the measures to be applied to minimize sediment from the skid trail moving from the 240 feet of skid trail in the WLPZ towards the Class II watercourse.

Stop 14: Exposed Utility Line R3-1.

Page 28 of the NTMP describes the problem as groundwater seeping out of the bank on the south side of the road has created a gully in the road surface exposing utility lines (photos 3168-3170). The exposed utility lines are a 12kv electrical line owned by PG&E and two Verizon phone lines. The gully flows down the road surface for several feet and then turns, along with the utility lines, towards the north. The gully leaves the utility right-of-way about 70’-100’ north of R3-1 (photo 3166, 3167). The gully heads downslope towards M17-2. The gully should be mapped on page 42.2 as a Class-III.

The plan of action for R3-1 depends on cooperation of the two utility companies. Various plans were discussed for addressing the problem Dave Hope, RWQCB, stressed the importance of diverting any water that did not naturally belong. One of the Big Creek Foresters suggested the possibility that the groundwater was coming from the spring tapped by the LomaPrietaSchool.

The map on page 42.1 suggests the possibility that water that leaves the gully in the road surface at G11-1 may travel downslope to R3-1 and contribute to the problem there. This possibility should be examined in the field. If this is the case, repair of the road at G11-1 and proper drainage for the repaired road may reduce the amount of groundwater seeping from the road cut at R3-1.

Stop 15: M14-1.

The NTMP proposes about 200 feet of inside ditch to drain groundwater seepage from the cutbank. I speculate that removing this groundwater seepage may reduce the water concentration at R3-1 and help reduce the future potential to erode the road surface after the mitigation at R3-1 has been applied. Note that M14-1 is about 250 feet upslope from R3-1.

Stop 16: G11-1.

See page 20 of the NTMP for details. A 2-5 foot gully has formed along the road surface exposing utility lines. The gully was apparently caused by watercourse on an adjoining property was diverted don the road. The diversion appears to have been corrected. The fill over the utility line may not have been properly compacted. The proposed mitigation is to backfill the gully with moist-compacted earth. Follow the recommendations of California Geologic Survey.

Stop 17: G10-1.

About 150 feet of a proposed road 650 feet long will cross 55%-65% slopes on a full bench cut to reach Morrill Road. Details of the proposed mitigation are on page 20 of the NTMP. Follow the recommendations of California Geologic Survey.

Stop 18: M11-1 and M12-1.

Skid trails on slopes 50%-65% with a High EHR, see page 14 of the NTMP. Dave Hope, RWQCB recommend that the few trees to be accessed by hauled upslope using a long-line. Michael Huyette, CGS, pointed out that the Plan did not provide for traffic control on Wrights Station Road downslope.

Stop 19: Osprey Nest.

Walked down Wright Station Road to view an osprey nest.

Photo 3172 shows the steep scarp along the head of the Class-II that is crossed at R1-1. Failure cracks were observed along the east bank of the Class-II about 15-20 feet from the break in slope at the top of the Inner Gorge. 

Stop 20:  Class-II Crossing R1-1.

Place a Class-II crossing along an existing road proposed for reconstruction. The details are given on page 28 and on page 296-297 in the Geology Report. Photos 3173 and 3174 show the channel at or near the proposed crossing. A 36” by 50 foot long culvert is proposed. The western approach will be cut down 3-4 feet. The proposed crossing will require about 150 cubic yards of fill with a maximum depth of about 7 feet. Fill will be keyed below grade and will be compacted around the culvert. The inlet and outlet will be rocked to the top of the culvert.

The proposed culvert may be capable of carrying the 100-year water discharge but it is likely that debris flows will periodically move through this section of the Class-II. The head of the Class-II is very steep and failure cracks were noted on the walk down to R1-1 (discussion of photo 3172 above). The proposed culvert may not be able to handle debris flows. Therefore, a bridge would be the environmentally superior choice of a crossing at this location.

Mitigation Points M5-1 and M8-1 should be put back into the plan since the EHR of the soil should be High not Moderate as in the NTMP (see discussion at the beginning of this report). Thus, M5-1 and M8-1 are skid trails on slopes between 50% and 65% on soils with a High EHR. Request that M5-1 and M8-1 be visited on the next PHI. 

Stop 21: Class-III Crossing R2-1.

Page 28 and page 298 describe R2-1 as a seasonal crossing of a small watercourse draining a hydric area. Presently, some of the storm flows appear to be going down the road surface towards R1-1. Page 28 says that the soils in the hydric area are relatively dry in the summer months. Upslope of the proposed crossing there were some wet areas. One of the Big Creek Foresters mentioned that water appears to bubble out of the ground in the winter. Photo 3175 shows the entrance to a soil pipe in the hydric area.

The NTMP offers three options: a temporary crossing; a rock ford; or a 24” culvert. The northern edge of the road is at the break in slope. Any action that lowers the subsurface control on flow out of the hydric area has the potential to increase the discharge out of the hydric area which may in turn lead to drier conditions in the summer in this valuable habitat area.

I recommend a temporary crossing that will be removed after operations. I also recommend that storm flows be prevented from traveling down the road surface.

Stop 22: S4-1, Class-II Tractor Crossing.

The tractor crossing is on flat ground and the Class-II is not incised (Photo 3176). A temporary crossing will be made by placing straw on the streambed prior to placing log bundles that are cabled together to protect the bed and bank during skidding operations. If water is present, a pipe (4” minimum diameter) will be place in the streambed.

Stop 23: G8-1.

An old road in a broad swale is offset 18-24 inches by a scarp from the 1989 earthquake (Photos 3177 and 3178). There is a potential for a Class-III to form in the swale. A 48” culvert under the road was recommended.

Stop 24: Landing 2.

Landing 2 will be between 0.25 and 0.5 acres in size and serve as a helicopter landing (photos 3179 and 3180). The general area is flat and will probably not require much grading.

Stop 25: Class-III at base of Dam.

Photos 3181-3183 show the bed of the Class-II below Landing 2. Slide G-2 is just upstream. Debris flow deposits were noted in the streambed.

End Day-1

August 16, 2006

Stop 1: No Mitigation Number

Old jeep trail on ridge from Landing 40 (map on page 42.13) will be turned into a fire break with waterbars spaced as appropriate for High EHR. RWQCB started a discussion about the inadequate condition of the road along the south shore of Lake Elsman. The road will be used to transport personnel such as fallers and therefore is part of the NTMP. CDF, CGS and RWQCB all want the road upgraded to FPR standards and made part of the Road Maintenance Plan. I support this position. 

Stop 2: Williams Reservoir. No Mitigation Number

Photos 20 to 30 show the area around Williams Reservoir. There is a small saddle dam in the northwest corner of the lake. There are signs of erosion downslope of the saddle dam indicating that it is overtopped during storm events. Only about 2.5 acres of the plan is upslope of the reservoir. The area above the reservoir is in the helicopter unit. The Lexington Fire, 1985, reportedly contributed a significant amount of sediment to the reservoir.

Stop 3: Look at Example Marking in Unit 1 Below Sears Road.

Climbing down the road embankment I noticed what appears to be a soil pipe, photo 0031. People climbing down the embankment before me apparently pushed the overlying debris away from the soil pipe. Photo 32 is looking back up the embankment from the location of the apparent soil pipe.

Class-II from crossing R1-1 goes through the sample marking area below the road. The watercourse divided into at least two channels on its way down to Los Gatos Creek. Observed soil piping near the base of trees to the east of the watercourse (photos 0033-0035). Photos 0034-0040 show the Class-III at various locations on the way down to Los Gatos Creek. There is a flat area part way down where significant amounts of sediment have been deposited and where the channel divides (photos 0039-0040 and 0052-0053).

The eastern channel goes subsurface as it crosses an old road bench on the top of the streambank. The bank failure at the point where the eastern channel crosses the road bench shows signs of groundwater seepage where flow from the Class-III channel that went subsurface probably re-emerges (photos 0045-0048). The larger western channel cuts across the road bench.

Met Chris Rombough on his way downstream. He reported that upstream of this point the embeddedness average about 70%.

Bankfull on Los Gatos Creek appeared to be about 2.5 to 3 feet above the current water surface. The geomorphic floodplain was on the Left Bank (south bank, 0050-0051) to the east of the Class-III and on the Right Bank (north Bank, photo 0043) to the west of the watercourse. Fine silt was visible along the margin of the left bank in the vicinity of the Class-III. The cobble at the crest of a riffle had a light dusting of silt.

According to Kent Aue, DFG, the Santa Clara Valley Water District electro-fished between Lexington Reservoir and LakeElsman and found rainbow throughout the reach.

Stop 4: Landing 1 near mouth of Austrian Gulch.

Landing 1 (page 42.16) is on the north shore of LakeElsman near the Austrian Gulch helicopter unit. Local Air Quality Control Board must be notified because of the serpentine soils (photos 0056-0058).

Stop 5: Large Soil Pipe

Large soil pipe discharging above road to Austrian Gulch (photos 0059-0062).

Stop 6: Austrian Gulch Delta

Delta of Austrian Gulch at bridge (photos 0065-0072).

Stop 7: Road Drainage Sediment Deposit

Tom Lippe, Santa ClaraCounty, Richard Fitzgerald, DFG, Andy Morris, Big Creek Lumber and Dennis Jackson, Aldercroft Water District, investigated Austrian Gulch. Road Drainage formed a deposit of sediment (photos 0073, 0076, 0077) in the Class-II tributary of Austrian Gulch a few yards upstream of its confluence with Austrian Gulch. The road drainage comes from the large hairpin turn. Photos 0074 and 0075 show the road drainage ditch as it descends to the Class-II. Photos 0078-0080 show that the watercourse upstream of the entry of the roadside ditch is relatively free of fine sediment. Photos 0081-0083 show the fine sediment in bed of Class-II downstream of the point where the roadside ditch enters the watercourse.

Stop 8:

Photos 0084-0090 show Austrian Gulch upstream of the landslide marked on page 42.17 at one of the property corners.

Stop 9:

Photos 0091-0093 show the hillslope near the southern edge of the landslide on page 42.17.

Stop 10: Herbicide Spraying

RWQCB reported that herbicide was sprayed along the road near Wrights, see map on page 42.5

Stop 11: Mis-mapped Class-II and Soil Pipe

Discovered that the Class-III below the “Helicopter Unit” label on page 42.17 is actually a Class-II (photos 0094-0097). It has a Class-III tributary (photo 0103). Photo 0099 shows evidence that debris flows have moved down the channel. There is a 4-foot high waterfall in the channel (photo 0101) and groundwater is seeping out of the banks. Took a soil sample from the streambed at the confluence, and also took a soil sample from the hillside near the confluence of the Class-II and its Class-III tributary. Scooping up a handful of surface soil from the slope uncovered a soil pipe, photo 0106.

Stop 12: M18-4 Culvert Repair

A 60” culvert is causing erosion of the channel below the road fill (Photos 0107 to 0112). The mitigation is described on page 21-22 and map on page 42.5. An energy dissapator will be placed on the culvert outlet. The road prism will be elevated.

Stop 13: M16-5, M19-5 and M20-5

Did not stop at these mitigation points since we were trying to catch up with the main PHI group. Janet Web, Big Creek, described these measures as we drove past them. Dave Hope, RWQCB, later told me that he did not like the proposed mitigations because the road surface was 14% and the maximum allowable gradient for rolling dips is 8%.

Stop 14: Ostwald Intake

Ostwald Intake is operated by San Jose Water Company. Photos 0113 to 0126 show the channel of Los Gatos Creek at or slightly downstream of the Ostwald Intake.

Stop 15: Bridge Downstream of Ostwald Intake

Photos 0127 to 0135 show Los Gatos Creek at the bridge downstream of the Ostwald Intake. There is a large tree covered bar with an overflow channel along the left bank (photo 0135) just downstream of the bridge. All of the trees on the bar/island appear to be about the same age. Water is diverted into a 24” pipe and sent to the treatment plant adjacent to the dam at Lexington Reservoir.

Stop 16: Hooker Gulch

Photos 0137-0142 are of Los Gatos Creek at the confluence with Hooker Gulch. Photos 0143-0147 are of Hooker Gulch.

Stop 17: Recent Slide on Road above Los Gatos Creek

Photos 0148-0151 show a recent slide along San Jose Water Company road on the right bank of Los Gatos Creek, downstream of Hooker Gulch. Photos 0153 through 0156 show the bed of Los Gatos Creek directly below the slide. Assigned a Mitigation Point number of M9-7. Material from the slide on road and over the bank needs to be dealt with prior to the rainy season. 

Stop 18:

Photos 0157-0166 are of Los Gatos Creek where the 24” pipeline from Ostwald Intake crosses the creek. Photos 0169 to 0171 show the pipeline right-of-way. Photos 0172-0177 show Los Gatos Creek near the point where an unidentified black pipe crosses the 24” water pipeline right-of-way. Photos 0178-0180 are of a Class-II close to the boundary of the NTMP. Photos 0182 and 0183 are of a Class-II with large trash racks in need of repair.

Stop 19: Chemeketa Intake

Photo 0186 shows the Chemeketa intake sump.

Stop 20: Ryland Dam

Photos 0189-0195 are of Ryland Dam and its defunct fish ladder.

Stop 21: Chemeketa Slide

Photos 0196 to 0203 are of the slide, G7-7, below ChemeketaPark. The NTMP describes the conditions on page 16 and on page 293. The slide is part of a large complex that encompasses all of the ChemeketaPark subdivision. The NTMP notes that road and rooftop runoff from ChemeketaPark subdivision are directed on to the slide. In fact, road drainage from outside of the subdivision also is directed onto the slide. In addition, the subdivision is on septic tanks which provide a widely distributed subsurface input of water from the septic tanks into the slide complex.

The NTMP states, on page 16, that,

No signs of recent or active movement of the large slide block were observed, however the overall morphology of the slide block is consistent with infrequent slow periodic movement and limited movement has probably occurred within the past 100 years. The NTMP proposes WLPZ and selection harvesting on this slide. It is unlikely the harvest will have any significant impact due to the low number of trees proposed to be cut, particularly in light of the large drainage area located upslope. The ChemeketaPark subdivision probably has a much greater impact on hillslope stability through the concentration of runoff from roads and rooftops. None the less, it is prudent from a public slope stability standpoint to limit the level of harvest on the steep slopes below ChemeketaPark for public safety concerns.

On September 2, 2006, Gary Shapiro told me that he has observed a large crack near the intersection of Comanche Trail, Nez Pearce Trail and Blackfoot Trail which is about where the large plastic pipe directs surface runoff down the scarp face. If this observation is confirmed it may indicate that the slide is actively moving. This observation underscores the necessity of maintaining the existing trees so they reduce the moisture content of the slide through transpiration.

The reasoning in the NTMP is flawed. The NTMP notes that public safety requires that the slope stability of the slide not be jeopardized. The NTMP then proposes harvesting trees from the slide, which has the potential to destabilize the slide. The NTMP makes the argument that since the removal of the trees is judged, in their opinion, to have less impact than the water inputs from the ChemeketaPark subdivision; it is alright to harvest the trees. This argument misses the point; the impacts from the ChemeketaPark subdivision have been occurring for a long time and represent the baseline conditions. The harvest proposed under the NTMP is a change in the present situation. If the NTMP actually harvests trees and slope stability problems materialize San Jose Water Company and Big Creek should be held liable for any damage.

A 5.5 acre Special Treatment Zone (STZ) is proposed for slide G7-7. The proposed STZ is very similar to that proposed for Geologic Mitigation G4 on Inner Gorges. My discussion of the G4 STZ above demonstrates that the proposed harvest methodology can not guarantee slope stability. While the proposed STZ for the Inner Gorges, G4, was an attempt to protect water quality, the STZ for G7-7 must protect public safety and therefore the NTMP must guarantee slope stability. Since people’s homes, and potentially lives, are at potential risk from the proposed harvest of slide G7-7, it is imperative that the most conservative standards be applied. The most conservative approach would be to exclude slide G7-7 from harvest. Therefore, I strongly recommend that no trees be harvested from this slide.

Sincerely,
Dennis Jackson

Hydrologist

Cc:       Aldercroft Height County Water District
            Chemeketa Park Mutual Water Company
            Dave Hope, Regional Water Quality Control Board
            Bob Curry, Geologist for Santa Clara County