Figure 6. Soil Taxonomy Subgroups, San Pedro Creek Watershed 24

Figure 7. Generalized Vegetation Patterns, San Pedro Creek Watershed

25 1.5 Project Purpose

The purpose of the San Pedro Creek Watershed Assessment and Enhancement Plan is to provide a better understanding of watershed processes and continue building the community coalition needed to implement additional restoration activities. This information will help to enhance one of the most significant fisheries on the central Coast of California. Specific objectives linked to this project include: Developing an assessment of the physical, biological and chemical conditions of the watershed. Preparing conceptual plans to manage and repair identified problems generally at specific sites. Setting priorities for restoration. Providing strategies to implement conceptual repairs and management programs.

The Assessment and Enhancement Plan also aims at anticipating and addressing future deterioration in the watershed as a result of the exacerbation of existing conditions.

26 2. WATERSHED ASSESSMENT

Section 3 provides a detailed description of San Pedro Creek Watershed. Information about the geomorphology, water quality, land use history, vegetation, and fish habitat is included. Each of these topics is the result of analyses developed by professionals, contractors, students and residents of the watershed. Due to the length of each report, each is included in the assessment plan in a separate volume.

Geomorphological Analyses (See Volume I)

Geomorphology is the science that investigates the landforms of the earth. Included are the forms on the land surface, the mountains, valleys, slopes, riverbeds and dunes, for example, and the submarine forms on the sea floor. Geomorphology describes the existing landforms, investigates the processes that create them, examines the relationships between landform and processes and seeks to explain landform development (Ahnert 1998):

In 2001, Laurel Collins, Paul Amato and Donna Morton developed a Geomorphic Analysis of the San Pedro Creek main stem. Collins, Amato and Morton analyzed the lower 2.6 miles of the creek determining current physical conditions and assessing the impacts of land use activities. Their report (Volume 1) provides process-related findings to support the success and cost-effectiveness of future restoration and management efforts focused on San Pedro Creek. The volume includes information about topography, climate, stream flow analyses, geology, landscape change, as well as an analysis of channel characteristics. Maps and graphs visually display the results of this detailed study.

Vegetation Analyses (See Volume II)

Mike Vasey conducted riparian and upland vegetation surveys of the San Pedro Creek corridor and watershed, assisted by Eugenie Mont Blanc, Mike Faden, Erika Kean and Tom Parker from SFSU. His riparian analysis of the main-stem and major tributaries is organized into eighteen reaches. A total of 205 vegetation samples were taken every 100 feet from the mouth of the creek to the upper reaches of the Middle Fork and South Fork. A total of 142 non- native invasive species (NIS) infestations were also mapped along these reaches. A vegetation

27 map of the entire watershed is being produced to provide insight into large-scale hydrological processes affecting the lower riparian environment. The general vegetation survey enables an analysis of frequency, dominance and the Relative Importance Value (RIV) for native and non- native species in each survey area. This information provides insights into good candidate species for use in revegetation and problematic NIS infestations that need control efforts. Overall findings as well as a detailed description by reach are included in the report. The survey also included the development of a detailed GIS map identifying and locating the results of the survey.

Water Quality Analyses (See Volume III)

Water quality monitoring is defined as the process of sampling, measuring, recording and analyzing various water quality characteristics (Bartram and Helmer 1996). An important objective of water quality monitoring is to provide managers with appropriate information that aids the decision-making process. Water quality studies are important tools that provide valuable and sufficient information to maintain a high level of stream quality or ecological integrity (physical, chemical and biological) (Eyre and Pepperell 1999).

Vivian Matuk, a Master student at San Francisco State University, Doctor Bernard Halloran, a doctor of University of California at San Francisco and the chair of the water quality committee of San Pedro Creek Watershed Coalition, and Doctor Jerry Davis, an Associate Professor of Geography at San Francisco State University examined the water quality of San Pedro Creek. This research sought to study the water quality of the stream considering the following objectives: 1) To establish and compare physical, chemical and biological water quality characteristics in San Pedro Creek Watershed during four sampling periods (winter (January-February), late spring (April-May), summer (July-August) and fall (October- November) (seasonal variability), 2) to compare in-stream physical, chemical and biological characteristics of the watershed to the San Francisco Regional Water Quality Control Board, the Environmental Protection Agency (EPA) or literature standards, and 3) to determine whether cumulative changes occur in water quality along the creek (variability over space). The method used in this study is a routine type of water monitoring involving the periodic

28 collection of samples from a number of fixed locations along the watershed (Bartram and Helmer 1996).

The results of this research provide important information about the water quality dynamics in the creek. This information helps in identifying sources of pollution and controlling their impact on the watershed and its ecological integrity; providing base-line information for decision-making; restoring, protecting and maintaining activities; establishing a permanent water quality testing program to ensure high water quality; and building a sense of the importance of the creek and its role in the watershed. Furthermore, this research could be used as a model for similar watershed programs that seek to develop a monitoring and protecting program in order to preserve urban creeks and their watersheds. Maps, photographs, and graphs summarize the results of this report.

Fish Habitat Analyses (See Volume IV)

This report describes a survey conducted by Hagar Environmental Science to assess the existing habitat conditions for steelhead within the San Pedro Creek watershed, and identify potentially limiting factors, needs for habitat protection, and potential for habitat enhancement. The habitat survey included detailed mapping of representative stream reaches, identification and reconnaissance-level evaluation of potential steelhead migration barriers, and recording visual observations of steelhead present in each survey area.

Titus et. al. in a report titled History and Status of Steelhead in California Coastal Drainages South of San Francisco Bay, still in preparation, report the following steelhead information from 1941 to 1988 (Marty Gingras, CA Department of Fish and Game, 2000, communicated this information from Titus et al. via email).

San Pedro Creek is somewhat unique in that it is a highly urbanized stream, which continues to support a naturally reproducing steelhead stock, in part due to the interests and efforts of local residents in the community of Pacifica. From an historical perspective, the California Department of Fish and Game (CDFG) files indicate that adult steelhead were seen ascending the stream to spawn in April 1941. At that time, ranches dominated the drainage area and it is assumed that the creek system was in relatively good condition. There was tidewater at the stream mouth, but no real lagoon. The main stem was about 4 km long and formed by flow from three forks, the "east" fork

29 being the only one with perennial flow. Water was diverted from the creek system for irrigation. However, by 1971 the creek habitat was severely degraded due to the effects of garbage dumping, rat poisoning, and wastewater discharge in conjunction with urbanization of the area. Apparently, a fish kill had occurred on 22 December 1970. Local citizens formed a committee to promote the protection and enhancement of San Pedro Creek (J. Ladd, CDFG, unpubl. memo. of 14 January 1971). Two adult steelhead were seen in the stream during a single spot check on 6 April 1972 (E. Armstrong, CDFG, unpubl. memo. of 7 April 1972). Adults ascended the stream during the winter of 1972-73 as well (D. C. Erman, UC Berkeley, unpubl. letter of 9 February 1973). San Pedro Creek was surveyed by the CDFG in July 1973. Urban debris was still common in the streambed, and spawning areas were both quantitatively and qualitatively limited. Rearing habitat was adequate, with the presence of pools and abundant riparian cover. Several barriers to upstream migration were identified, especially at culverts, and several diversions were observed, the largest being that for the North Coast County Water District. Storm drains discharged into the creek. Juvenile steelhead were observed in all reaches of the main stem. As determined from electrofishing samples, the trout ranged from 3.8 to 20.3 cm in length and averaged 8.9 cm. Steelhead were observed above all culverts on the main stem, but only below the water district diversion in the south fork of the creek system. The size-structure of the juvenile steelhead population in San Pedro Creek was investigated on four occasions during the 1970's. On 3 July 1973, steelhead were sampled by electrofishing at four main stem stations (K. R. Anderson, CDFG, unpubl. memo. of 29 August 1973). The fish ranged in size from 3.6 to 16.0 cm FL, and averaged 8.0 cm FL (SD = 1.8 cm, n = 220). Thus, rearing juveniles were age 0+ and 1+, and 0+ trout were proportionately dominant in number. Abundance estimates were also made in late summer 1973, by electrofishing seven stream reaches (15–61 m) and applying the two- pass removal method of population estimation (K. R. Anderson, CDFG, unpubl. memo. of 13 November 1973). Juvenile steelhead densities ranged from about 2.0 to 7.6 trout/m, and averaged (± SD) 5.1 ± 2.3 trout/m. Despite its somewhat degraded condition, the creek system continued to support relatively high densities of juvenile steelhead. On 10 October 1974, the average size of juvenile steelhead electrofished in four main stem reaches was 10.2 cm FL (range, 5.1–18.8 cm FL; n = 125). The largest trout (21.3 cm FL) was found in the South Fork San Pedro Creek (K. R. Anderson, CDFG, unpubl. memo. of 28 October 1974). On 17 September 1976, the average size of juvenile steelhead electrofished in two main stem reaches was 8.9 cm FL (range, 3.3–17.3 cm FL; n = 26). Overall abundance of juvenile steelhead was apparently lower than in previous surveys (K. R. Anderson et al., CDFG. unpubl. memo. of 24 September 1976). Finally, on 15 November 1979, the mean size of juvenile steelhead electrofished in two main stem reaches was 9.4 cm FL (range, 5.6–16.8 cm FL; n = 43) (I. L. Paulsen and L. Fish, CDFG, unpubl. memo. of 21 November

30 1979). Estimated densities were 0.2 and 0.9 juvenile steelhead/m, which were much lower than those measured in 1973. Despite apparent differences in relative year-class strength, these four surveys demonstrated that the juvenile steelhead population in San Pedro Creek consistently comprised two age-classes, 0+ and 1+, and that the 0+ group dominated numerically. The relatively small proportion of 1+ trout present in any given survey indicates that the main smolting age of steelhead in San Pedro Creek is age 1. During the winter of 1975-76, entry of adults from the ocean and their migration to upstream spawning grounds were apparently restricted due to a lack of precipitation and thus reduced stream flow. Consequently, no adult steelhead or redds were observed in San Pedro Creek on 26 February 1976. Several adult steelhead, two estimated at 2.7 kg each, were observed in the creek on 1–2 March 1976, however. The local warden estimated that 60 adult steelhead had been poached at Adobe Road Bridge during this period (G. Scoppettone, CDFG, unpubl. memo of 25 March 1976 and 19 April 1976). In March 1978, about 600 steelhead died in San Pedro Creek due to the storm drain discharge of an unknown poison, possibly chlorinated swimming pool water (The Times, San Mateo, 22 June 1978). By 1985, the headwaters of San Pedro Creek were protected by virtue of their inclusion in San Pedro Valley County Park. In March 1985, 800 Dry Creek steelhead (8.8/kg) were stocked into the stream. When surveyed by the CDFG in May 1985 (J. Ford and L. Bordenave, DFG, unpubl. memo. of 29 July 1985), the creek system was in good condition overall. Steelhead spawning habitat was abundant in the upper main stem, or middle fork, but lacking in the north and south forks. Most spawning occurred within the park boundaries. Spawning reportedly occurred as late as May, and during the 1984–1985 spawning season, there were about 40 pairs of spawning steelhead within a 30 m spawning reach. Obstructions for upstream migrating spawners were identified, and storm drain pollution was still cited as a problem. Indeed, on 10 March 1987, 600–700 steelhead fry, yearlings, smolts, and adults were killed in the north fork and 2 km of the main stem as the result of a toxic storm drain discharge, probably chlorinated swimming pool water. The lowermost 880 m of San Pedro Creek was surveyed by the CDFG on 28 September 1988 (C. Dayes and D. Becker, CDFG, unpubl. memo. of 21 October 1988). Age 0+ and 1+ steelhead, up to about 20 cm in length, were observed throughout the reach, including the lagoon. Riffles provided over 464 m2 of spawning gravel for steelhead. Rearing habitat was good to excellent, and included abundant streamside riparian vegetation. Notably, the creek had continuous flow to the lagoon and contained two consecutive year- classes of juvenile steelhead, despite two consecutive drought years.

This information, as well as the other reports, will be used by the San Pedro Creek Watershed Coalition in setting priorities for adaptive management, educational activities, or restoration projects by considering the practicality of addressing key limiting factors and weighing the relative benefits to be expected.

31

Ongoing Studies

The Coalition’s team feels that the study of San Pedro Creek and its watershed is an ongoing process, as befits the Adaptive Management approach. The major findings included in the four volumes of this report have produced new questions during this project, and some of these questions have been addressed in the following short reports: 1. Longitudinal Profile and Rosgen Classification of Reaches 2. Storm Response of Water and Turbidity Levels in Two Tributaries of San Pedro Creek 3. Optical Brighteners Sewage-Source Study.

32 San Pedro Creek Longitudinal Profile and Rosgen Classification of Reaches – Fall 2001

Laurel Collins and Jerry Davis

Surprisingly, no longitudinal profiles have ever been surveyed of the entire main stem of San Pedro Creek. Geomorphologists (Collins and Davis) associated with the San Pedro Creek Coalition recently completed a profile of the main stem from Peralta Bridge into San Pedro Valley County Park. For our profile, we stopped at Peralta Bridge because the Flood Control Project a short ways downstream will dramatically change the profile in that reach, as soon as it opens. The graph "straightens out the curves" of the creek displaying channel length on the horizontal axis and channel elevation on the vertical. In order to see the whole profile, the view shown here has a vertical exaggeration of 43 times.

Figure 8. Longitudinal Profile from Peralta Bridge to Horeshoe Pit Bridge.

For the survey, the team used a tripod-mounted optical level, stadia rod and survey tape to capture elevations of (1) the deepest part of the channel – called the thalweg (Ger. "valley way"); (2) the water surface at base flow; (3) the bankfull elevation; and (4) various terraces. This

33 technique was very accurate: in a 8200 feet length of the channel – from Peralta to Linda Mar Blvd. bridges – the elevation error was only 0.01 foot. The apparent gradient detected in this profile differs markedly from that derived using contours on the 1993 USGS Montara Mountain 7.5’ quad (Figure 9).

Many factors will influence the shape of the profile. As described in Volume 1, a major historical impact to the profile is the channelization of the lower-most reaches, especially below Adobe. Flashy, erosive runoff from impervious cover adds to this impact. What can we see in the profile? 1. The creek's profile has some peculiar patterns that relate to the history of impacts. Clearly the biggest impact can be seen at Capistrano Bridge, where a knickpoint was created in the early 1950's by a grade control structure, perhaps at the upper end of a progressive headcut resulting from 19th-20th century channel straightening in the lower-most reaches, when up to a mile of effective channel length was lost as the creek was diverted from Lake Mathilda to drain directly to the ocean. The effect at Capistrano Bridge has been most dramatic during the last 50 years. Since 1960, fifteen feet of vertical erosion downstream of the structure has created a serious barrier to fish migration, plus some serious headaches for downstream residents losing their backyards. A succession of largely ineffective fish ladders have been installed, but this barrier remains and addressing it is a top priority for improving passage to important habitat upstream. 2. Both downstream and upstream of Capistrano, the creek's gradient has eroded to a lower gradient than must have existed before settlement. The average baseflow gradient below the Capistrano fish ladders and above Adobe Bridge is 0.91%, with a similar gradient (0.90%) at the bankfull level. In this reach, the uppermost terrace, which appears to relate to the bankfull level before settlement, has a gradient of 1.07%. The lowered channel gradient is likely the result of erosion from more frequent peak flows from urban runoff (rainfall on paved areas runs off quickly.) The potential for further erosion will depend upon whether this profile is flat enough to be in dynamic equilibrium with the flashy urban runoff it is provided. Unfortunately, the likelihood is that it is not, and even more erosion will occur unless something is done to decrease the flashiness of the runoff.

34 3. Most of the bridges serve as grade control structures, and this can be seen by looking at the profile at these points. Bridges at Adobe, Capistrano, Linda Mar and Oddstad all force the creek through concrete box culverts, creating a limit to downward erosion at that point in the profile. This is all right for the sections immediately upstream, but it invariably creates a fish migration barrier as a steep step and deep pool develops downstream. This is why people often see fish on the downstream side of Adobe Bridge. 4. Below the North Fork confluence and extending downstream to the next grade control structure at Linda Mar Bridge, the gradient has similarly been flattened as a result of urban runoff, primarily from the North Fork watershed and delivered by its system of culverts draining Park Pacifica. While the upper terrace gradient is 1.85% in this reach, the water surface and bankfull gradients are 1.09% and 1.07% respectively. 5. For the same reason, the main-stem upstream of the North-Fork confluence has been steepened to a gradient of 1.8%. This is because the downcutting below the confluence creates a steeper gradient in the main channel draining into it. This steeper gradient will no doubt create a headcut, which will migrate upstream until it reaches the next grade control structure at Oddstad Bridge. This is where we should expect the next major barrier to fish migration, as a deep pool develops downstream of the concrete pad under the bridge.

This profile has now been integrated with Rosgen classifications interpreted by Laurel Collins. The changing classifications along the stream’s length can be seen in Figure 10 a-d. The added detail of the profile, especially coupled with Rosgen classification integration indicating stable and unstable sections, will help guide restoration efforts. We are now in the process of identifying and surveying cross sections in areas of special concern, especially below Capistrano Bridge.

Repeating the longitudinal survey in a few years will also help us to understand erosion rates in various reaches. The section from the park down to just below the North-Fork confluence has in fact been surveyed on three successive years recent, and from this temporal view we can see in this some surprising effects. For example, upstream of the Oddstad bridge grade control structure, there has been significant downcutting – approximately 1.5 feet in two years. Why is

35 this happening in a park, with the only significant rapid runoff coming from the few gravel roads and a small parking lot at the visitor center? The answer, being investigated by students at SFSU, appears to be that we're seeing the response of the creek to a major depositional event from the 1962 debris flow that wiped out John Gay's trout farm operation. The creek is now rapidly cutting through these quite recent deposits.

We will probably discover other surprises when we repeat the downstream survey. We may be able to detect which sections are possibly stable, and which are heading for failure. We will need the cooperation of all creekside residents. The key to the success of any restoration project is taking the longitudinal view: (a) what happens at any point relates to things both upstream and downstream; and (b) what you do to any part affects the creek both upstream and downstream. This profile helps us to see it.

Fig. 9. Comparison of longitudinal profiles from contours and field survey (L. Collins).

36

Fig 10. a-b. Profile, gradients and Rosgen class, 3000-5000 ft. from mouth (L. Collins.)

37

Fig 10. c-d.. Profile, gradients and Rosgen class, 5000-7000 ft. from mouth (L. Collins.)

38

Fig 10. e-f.. Profile, gradients and Rosgen class, 7000-9000 ft. from mouth (L. Collins).

39

Fig 10. g-h. Profile, gradients and Rosgen class, 9000-11000 ft. from mouth (L. Collins).

40

Fig 10. i-j. Profile, gradients and Rosgen class, 11000-12000 ft. from mouth (L. Collins).

41

Fig 10. k. Profile, gradients and Rosgen class, 13000-13800 ft. from mouth (L. Collins).

42 Storm Response of Water and Turbidity Levels in Two Tributaries in San Pedro Creek Paul Amato, January 2002

During part of the water year of 2000, data was collected in two tributaries of San Pedro Creek, to estimate rainfall in the watershed, and discharge and turbidity values of the two largest, and similar sized sub-watersheds. The point of the study was to try and improve the rainfall estimates in the watershed and to compare discharge and turbidity levels in the developed North Fork tributary with the undeveloped Middle Fork tributary. Two Rainwise tipping bucket rain gauges were installed, one on Sweeney Ridge to measure rainfall at the top of the North Fork, and the other near Montara Mountain to measure precipitation in the Middle Fork. Rainfall data was collected with a continuous event counter, activated each time 0.01 of an inch of rain fell. This information was then compared to the long-term daily records taken since 1978 at the San Pedro Valley Park near the center of the watershed. Discharge values in each of the study sub-watersheds were derived by measuring water depth near the confluence using Global Water water pressure level transducers installed near the tributary confluence. The North Fork sensor was installed by securing the sensor near the bottom of the concrete culvert that forms most of the main channel of the North Fork. The Middle Fork sensor was installed in a plastic PVC pipe upstream of any significant development. Values were collected using a continuous recording data logging system. A Swoffer flow meter was used to measure velocity and determine discharge values for future conversion of water level readings to discharge. Global Water transmittance turbidity sensors were installed with the water pressure level transducers and data was collected using the same data logging system.

As shown in the graph below, a consistent rainfall pattern can be seen between the Park, the North Fork watershed, and the Middle Fork watershed. This pattern was looked at as a way to determine a long-term rainfall average for the entire watershed. The monthly average rainfall was calculated for each recorded location between February and May. The Park was 5.67 inches, the North Fork was 4.71 inches, and the Middle Fork was 6.51 inches. This pattern may be explained by the watershed topography and by the prevailing wind during storm events. Storms typically move in from the south, where they are slowed by Montara and San

43 Pedro Mountains, causing increased precipitation. The Park is located on the valley floor at the back of the watershed. Storms may be moving slowly past the Middle Fork then releasing moderate rainfall over the Park as they are backed up at Sweeny Ridge to the North. It may be that the North Fork then experiences a slight rain shadow effect in comparison to the other locations on record. The average of the North Fork and the Middle Fork gauges for the months of February through May equals 5.61 inches, a value very close the average rainfall recorded in the Park during the same period. It may be that the Park is a suitable average for the watershed and that it can serve as an accurate long-term rainfall record location.

San Pedro Creek Rain Gage Comparison 2000 Rain Year

17 16 15 14 13 Park 12 n) i 11

( North Fork 10 on 9 ati 8 Middle Fork pit 7 6 Preci 5 4 3 2 1 0

r t r y ry ril y rch Ma une July be obe Ap J ugus brua Ma em Oct vember cember Januar A Fe ept No De S Month

Figure 11. San Pedro Creek Rain Gage Comparison 2000 Rain Year

Preliminary analysis of water level response shows a distinct difference between the unurbanized Middle Fork watershed and the North Fork, which is 19% impervious due to development. Values on the Y-axis of the graphs are simply an electronic signal in milliamps (mA) that increases as the water level depth increases over the sensors. Depth and discharge will later be derived from these values using known cross-sections and measured discharge at the sensors. Data is shown from approximately 11:00 PM on February 12, 2000 when a storm event began, to approximately 6:45 AM on February 15, 2000 when the Middle Fork water level appears to return to pre-storm levels.

The Middle Fork responds gradually (Figure 12), peaking at two different times during the storm. This shape is more typical of an unurbanized watershed that experiences slower runoff

44 response and less runoff contribution to the stream due to adequate surface infiltration. Runoff gradually increases as continued precipitation saturates the ground, limiting infiltration. This is represented by the peaks in the graph. The peaks are then followed by decreases in water level as precipitation decreases causing runoff to diminish. Eventually, the storm stops and the water level returns to pre-storm or near pre-storm levels.

The North Fork is a much flashier system, as shown by the irregular line (Figure 13). This is direct evidence that runoff is reaching the channel of the North Fork much faster and more frequently and that the watershed responds very quickly to changes in rainfall. Unlike the Middle Fork, the North Fork water level is more sensitive to smaller changes in rainfall. This is due to increased impervious area, decreased infiltration, and increased runoff.

Changes in turbidity levels in the Middle Fork (Figure 14) appear to be influenced by the amount of discharge in the channel. Like the water level, turbidity is represented as milliamps (mA) on the Y-axis. This data will later be converted to nephalometric turbidity units (NTUs). For general understanding the following approximations can be made: 4 mA is equal to 0 NTU, 6 mA = 100 NTU, 8 mA = 200 NTU, 10 mA = 300 NTU, 12 mA = 450 NTU. In the Middle Fork, as water levels increase, turbidity levels increase until a point where discharge increases seem to dilute turbidity levels causing a decrease in the concentration of suspended matter in the water column. This inverse relationship is evident upon comparison of the highest point in the water level line and the lowest point in the turbidity line for the Middle Fork. The highest turbidity levels are then sustained for several hours as the water level drops, peaks, and drops back to pre-storm levels.

Like water level, North Fork turbidity levels are flashy, responding quickly to increased precipitation and runoff. The highest turbidity levels appear to correspond with the highest water levels as seen by comparison of the two most significant peaks in water levels with the two most significant peaks in turbidity levels.

The overall turbidity levels are also less in the North Fork than in the Middle Fork. This can be attributed to reduced sediment sources due to increased impervious area and reduced natural channel bed and banks in the North Fork.

45

San Pedro Creek Middle Fork Water Level Response (Between 2/12/00, 11:04 PM and 2/15/00, 6:44 AM) 7

e

ev *Water level response is L 6 shown in milliamps ater

W 5 n i 4 ange Ch 3 02/12/00 02/13/00 02/13/00 02/14/00 02/14/00 02/15/00 02/15/00 Date

Figure 12. San Pedro Creek Middle Fork Water Level Response

San Pedro Creek North Fork Water Level Response (Between 2/12/00, 11:08 PM, and 2/15/00, 6:38 AM ) 7

e 6

pons es A)* R 5 (m vel

Le 4

Water 3 02/12/00 02/13/00 02/13/00 02/14/00 02/14/00 02/15/00 02/15/00 Date

Figure 13. San Pedro Creek North Fork Water Level Response

46 San Pedro Creek Middle Fork Turbidity Response (Between 2/12/00, 11:08 PM and 2/15/00, 6:44 AM)

12 11 10 9

esponse 8 A)*

R 7 y (m 6 idit 5 4 Turb 3 2/12/00 2/13/00 2/13/00 2/14/00 2/14/00 2/15/00 2/15/00 Date

Figure 14. San Pedro Creek Middle Fork Turbidity Response

San Pedro Creek North Fork Turbidity Response (Between 2/12/00, 11:08 PM, and 2/15/00, 6:38 AM)

12

mA)* 11 ( 10 se 9 8 pon

es 7

R 6 5 4 rbidity 3 Tu 02/12/00 02/13/00 02/13/00 02/14/00 02/14/00 02/15/00 02/15/00 Date

Figure 15. San Pedro Creek North Fork Turbidity Response.

47 The use of Optical Brighteners to assess sewage contamination in surface waters Bernard Halloran, Carmen Fewless, Christine Chan, Vivian Matuk, Jerry Davis

As described in Volume III, water quality testing showed extremely high levels of coliform bacteria including E. coli and Streptococcus. Studies indicated high total coliform levels (as much as 40,000 cfu/100 ml) in the creek but the actual source of bacteria is still not known. In the most heavily polluted areas, the North Fork and mouth of the creek, bacteria levels exceeded California State water quality maximums by more than 40 fold.

Because of these studies, we have evidence that San Pedro Creek is polluted, however, as stated, it is difficult to determine exactly where the pollution is coming from. It is possible that the water pollution problem is the result of leaking sewer pipes (human source), pet litter that inadvertently finds its way into the creek, or through naturally occurring processes such as animal feces from deer, raccoon, and other animals living along the creek. To help determine the source of the bacteria, the SPCWC’s Water Quality Committee, with the help of Carmen Fewless (a graduate student at Cal. State, Hayward) and Christine Chan (SPCWC Projects Coordinator) has begun testing for Optical Brighteners (OBs) at various sites along San Pedro Creek.

Optical Brighteners are fluorescent compounds found in laundry detergents that are used to increase the brightness of cotton clothes (makes our cotton clothes brighter and whiter) and that appear in sewage-contaminated water. The SPCWC is using optical brighteners as a means of distinguishing whether sewage is contributing to the bacterial load of the creek. Optical brightener compounds are in most laundry detergents but are not found in dish or hand soaps. When home washing machine’s, which are connected to our sewer system, empty used soapy water from the washer, the soap also carries with it the remaining optical brightener compounds. If the sewer pipes are leaking, the optical brighteners escape into the ground water and eventually make their way into the creek. To test for the presence of optical brighteners in San Pedro Creek, we place a small cotton pad (about 2 inch square, OB-free) mounted in wire baskets, in the creek in regions of moderate to high flow for periods of up to 7 days. After 7 days, the cotton pads are removed, dried, and placed under a UV A lamp to induce fluorescence. If during that 7 day period, there are optical brighteners present in the creek water, the optical brighteners

48 compounds stick to the cotton pad just as they do to our cotton laundry and when exposed to ultraviolet radiation (black light) will fluoresce. The SPCWC’s Optical Brightener testing program will take place over the next 12 months and results should be available during the summer of 2002.

Optical Brighteners Testing Along San Pedro Creek (Phase One): The San Pedro Creek Watershed Coalition has obtained a grant from the Regional Water Quality Control Board to begin testing for Optical Brighteners along four sites along San Pedro Creek. The first site, located on the Middle Fork, is our control site and is situated just outside of San Pedro Valley County Park. At this site, the creek water has moved through San Pedro Valley County Park, but has not yet reached areas of urbanized development. The second testing site is located approximately 400 feet from the North Fork Culvert before the creek mixes with the Middle Fork. The North Fork is most problematic of the sub-watersheds in that its upland drainage areas are steep and drain rapidly into culverts. Coupled with storm-drains from impervious surfaces along developed areas, the North Fork sub-watershed and the area surrounding its outfall is considered one of the most highly contaminated areas in the creek. The third sampling site is located along the Main-stem. The Main-stem is entirely within public lands, with the exception of a small inclusion of private land, which cannot be developed, and thus has fewer problems than the North Fork. This site was chosen because it provides the SPCWC with the ability to test for Optical Brighteners after the confluence of the Middle Fork (Control Site) and the highly contaminated North Fork. The final sampling site is located at the mouth of San Pedro Creek at Pacifica State Beach. This sampling site was chosen to help the San Pedro Creek Watershed Coalition determine if the OB’s were actually making there way through the Linda Mar Valley and into the Pacific Ocean.

49

Figure 16. Optical Brighteners Testing Phase I Sampling Sites

Optical Brighteners Testing on the North Fork of San Pedro Creek (Phase Two): The San Pedro Creek Watershed Coalition has obtained a grant from the San Mateo Countywide Storm-water Pollution Prevention Program (STOPPP) to expand its optical brighteners testing program to the North Fork in an effort to find the source of the high bacterial levels in San Pedro Creek. With assistance from Carmen Fewless, Christine Chan, Bernard Halloran and Brain Martinez, Assistant Superintendent of Calera Creek Water Recycling Plant, the San Pedro Creek Watershed Coalition has begun testing a total of 9 sampling sites in the North Fork. Sampling will take place along Terra Nova and Oddstad Boulevards in pre-selected storm sewers and storm drains using city planning maps that identify approximate locations and diameters of each storm and sewer drain. Initial sampling will take place in storm sewers and storm drains located in the lower half of the North Fork along Oddstad and Terra Nova Boulevard’s. If Optical Brighteners are detected, the sampling locations will then be moved up Oddstad and Terra Nova Boulevard in order to isolate areas with suspected sewer pipes leaks.

50 Sample sites are either labeled “O” for Oddstad or “T” for Terra Nova and numbered according to the location and order in which the pads are placed.

While results to date must be considered preliminary, we are clearly identifying optical brighteners in many of the samples, with the greatest signal from the North Fork. While this might not expected considering the proven concentration of bacterial pollution at this site, it is in fact surprising given the relatively young age of sewer connections upstream (primarily 1970’s). The detailed results of the second phase of sampling will help us to understand these sources.

Figure 17. Optical Brighteners Testing Phase II Sampling Sites

51

3. SYNTHESIS OF WATERSHED ASSESSMENT

The assessments described in this report provide us with a picture of the watershed and its major stream corridors. The biogeomorphic, ecologic and hydrologic systems in this watershed are interrelated, and only through a comprehensive understanding of all can we start to undertake restoration projects.

Stream channel bed and bank material analyses described in the geomorphic analysis (Volume 1) and subsequent longitudinal profile demonstrate that the creek is subject to many human impacts. The full suite of bed and bank stabilization methods are illustrated along its length: riprap, gabion, wood and concrete revetments, concrete culvert structures at bridges, and remains of old dams from the farming period. A long history of impacts to this watershed beginning in the late 18th century have left many marks, including significant channelization of the lower reach and tributaries. Bank erosion has been identified as a major source of sediments. Creek observers frequently report turbid conditions at the Linda Mar Bridge (for location, see Fig. 18) even when the middle, south and north fork inputs are relatively clear. The Rosgen classification of stream reaches linked to a detailed longitudinal profile will provide useful and significant tools for stream restoration projects.

In addition to the important information on channel characteristics in Volume I, we have begun evaluating the significance of historical changes in land use, sediment sources and their impacts on channel erosion. From discussions with local residents, aerial photographic and field interpretation of stream terrace ages (from using growth whorl analysis of red alders- Alnus rubra), we can see the effects of debris flows with origins in South-Fork areas impacted by dirt biking. Two major debris flow events of widespread significance in the upper watershed occurred in 1962 and 1982. We are still seeing the effects of these events in channel erosion processes in the creek. The anomalously high incision rates noted in a two-year study (Amato 2002 pers.comm) of the upper mainstem (above the north fork confluence) can be understood as a response to relatively recent debris flow deposition events. We believe that a more through sediment sources analyses is needed to better quantify these effects.

52 Also important to planning a restoration project is a good understanding of the magnitude of hydrological inputs: precipitation and runoff. Our studies indicate watershed precipitation averages 38 inches (965 mm) annually. This is significantly higher than the 33-inch (838 mm) estimate reported in the hydrologic engineering report of the Army Corps' flood control project Environmental Impact Statement (1998?) (Appendix 1). Our estimates are based upon using data from two recording rain gauges (one in the north fork and one in the upper south- middle fork) to support the use of long-term precipitation results from the San Pedro Valley County Park as representative of the basin as a whole. The 38 inches (965 mm) figure is based on 23 years of record (1978-2000) at the park. This figure can be used to predict stable channel configuration using regional curve methods (Dunne and Leopold 1978).

Any in-stream restoration projects will also need to consider the contrasting responses of more and less urbanized subwatersheds, especially the north fork and middle-south fork (see Amato “Storm Response…” section above). Another runoff effect significant to this watershed is the probable maintenance of perennial flow in upper tributaries by fog drip. While we have conducted no fog-drip studies in this watershed, dense fog is a frequent occurrence and a contributor to stream flow elsewhere.

This watershed has experienced a long history of European-origin impacts starting with establishment of an asistencia in the late 18th century. Intensive grazing and agriculture produced many effects in the 19th and earlier 20th centuries: gulling on south facing grass covered hillsides; draining and diking of wetlands in the lower valley and the resulting channel erosion effects described in Volume I; and the introduction of non-native species altering the riparian corridor (Volume II). Sub-urban development from the 1950's thru 1970's (described in Volumes I) exacerbated the channel impacts by dramatically expanding areas of impervious covered. Today the watershed is approximately one-third built up, with a 13% overall impervious surface (EOA, 1998). Significant expansion of urbanized areas is not expected due to the Hillside Protection and Growth Control ordinances.

Our vegetation analysis (Volume II) has provided maps and analysis of riparian vegetation and the general characteristics of upland vegetation in the watershed. To make sense of the varying changes in riparian conditions, we have organized this information by reach (Figure 18)

53 and can now identify areas that need special attention for canopy gaps and removal of non- native species. For the most part, the creek is blessed with good canopy conditions though certain areas need attention. Through the Coalition's efforts, we have largely removed Arundo donax infestations. Cape and English Ivy remain the most pernicious invasive exotics.

Water quality analyses (Vivian Matuk, Volume III) comparing different sites along the creek during winter, late spring, summer and fall of the year 2000, provided significant information about in-stream physical, chemical and biological characteristics of San Pedro creek watershed. The dry-summer maritime type of climate of San Pedro Creek watershed directly influenced the water quality of the creek. Highest values of alkalinity, hardness, electrical conductivity, pH, total, fecal coliform bacteria, Escherichia coli and enterococcus were reported during the April-May and July-August sampling periods. The lowest values of water temperature, and highest values of turbidity and dissolved oxygen were reported during the winter period (January-February and October-November). Rainfall events and changes in the water temperature clearly influenced these patterns. Also, Matuk found that spatial variations were evident when comparing the sampling sites along the creek. Generally, the highest water temperature, pH, alkalinity, hardness, electrical conductivity and bacteriological values were reported at the North Fork. In addition, lower values of turbidity and dissolved oxygen were reported at that sampling site. Similar physical, chemical and biological values were reported at Linda Mar, Peralta and the Outlet sampling sites. The lowest values for parameters such as pH, alkalinity, conductivity, hardness, electrical conductivity, bacteriological analyses and water temperature were reported at Oddstad (the “control” sampling site). In addition, the highest dissolved oxygen and turbidity values were reported at the “control” site. Land-use categories, urbanization, inputs from the sewage and storm systems, and the influence of geology may explain the spatial variations and the water quality characteristics reported in this study.

Overall, Matuk found that San Pedro Creek is a well-oxygenated creek with somewhat alkaline water, at a fairly stable water temperature, with relatively “hard” waters and moderately conductive. Its water quality met most of the San Francisco Regional Water Quality Control Board, EPA and literature standards for a freshwater habitat. On the other hand, the creek samples did not meet the EPA’s bacteriological standards for water contact recreation bodies. Water quality is impaired, possibly due to inputs from the sewage and storm systems, and the

54 creek’s bacteriological contamination may pose a risk to public health even though it provides a significant habitat for aquatic species such as the steelhead trout. Matuk recommends developing additional and more intensive water quality-monitoring program to account for annual variability along the creek, especially at the North Fork where variations of parameters such as temperature might be significant factor for fish habitat.

Our Steelhead Habitat Assessment (Jeff Hagar, Volume IV) has helped to clarify the character of different major stream reaches and tributaries as habitat for spawning and rearing. The Middle Fork appears to have the greatest potential for spawning, as well as rearing to smolt size, while the main stem is important for rearing despite significant water quality and disturbance issues significant to steelhead – especially turbidity, alkalinity, and temperature. Hagar emphasized that additional temperature monitoring, especially of the North Fork, would help to identify if this parameter may be significant seasonally. Of the tributaries, the South, North and Sanchez forks were emphasized primarily for water quality and quantity concerns: the significance for potential diversions of South Fork flow by the water district, the diverse water quality problems associated with the North Fork, and sediment concerns from the Sanchez Fork. The danger of reduced flows from any South Fork diversions is especially significant if North Fork runoff is removed due to water quality concerns. While the report doesn't emphasize habitat potential for Sanchez, he did note observations of small resident trout, and many of the limiting factors – a major barrier and a steep gradient downstream – can be addressed by relatively inexpensive restoration projects. The primary concerns Hagar recommends addressing, however, are barriers to fish passage, especially at bridge culverts, listed in order of decreasing importance as Capistrano, Linda Mar, Oddstad, and Adobe. The important spawning habitat identified in the Middle Fork is upstream of all of these barriers.

55

Figure 18. Reach and Impediments, San Pedro Creek Watershed

56

4. RESTORATION ISSUES AND ALTERNATIVES

Each volume of our assessment above notes specific problems and recommends restoration needs. The basic categories of restoration goals relating most directly to anadromous fish can be summarized as: 1. Removal of impediments to migration 2. Enhancement of habitat for spawning and rearing

There are of course many ways of accomplishing these goals, and many locations along the creek where efforts can have the most impact. In considering the results of the Assessment, the Coalition met to discuss and prioritize projects, organized geographically by stream reaches (see Figure 18). Reaches were defined to subdivide the creek in sections of similar general character and level of impact, though the many detailed changes in character – especially mapped in the Geomorphic Analysis (Volume 1) as well as in the vegetation data – are important to consider, especially as specific projects are designed.

Table 2 lists an array of potential restoration projects. Each project is identified by reach location, specific site, its benefits, the problem it addresses, the restoration method proposed, cost estimates where possible, funding sources and required permits. Each project is also assigned a level of urgency: High (H), Medium (M), and Low (L).

The highest priorities are given to addressing serious fish passage impediments, especially at Capistrano Bridge where a fish ladder has become seriously compromised by downstream erosion, and the ladder itself continues to contribute to serious bank failures downstream. While likely to be an expensive project, stopping fish migration at this fish ladder closes off the best spawning areas along the creek, as identified by Jeff Hagar. The City of Pacifica and the San Pedro Creek Watershed Coalition (SPCWC) have agreed to work collectively to address issues of severe bank erosion and impediments to fish passage for the section of San Pedro Creek downstream of the Capistrano fish ladder in Pacifica. In Spring 2002, the SPCWC will conduct the necessary field reconnaissance work and survey creek conditions in the project area. Upon completion of the assessment, the SPCWC will graph and analyze the data and

57 then develop a conceptual restoration design to address erosion and fish passage issues. The conceptual design will be developed to work in combination with a series of designs already developed by L.C. Lee and Associates for the segment of creek immediately upstream of Capistrano Bridge. The conceptual restoration design will be presented to the City of Pacifica and L.C. Lee and Associates in the form of cross sections and a planform map using the Rosgen Stream Classification method. The major steps being pursued are:

1. Reconnaissance Meeting. Field reconnaissance meeting with Scott Holmes, Maria Aguilar, Jerry Davis, Christine Chan, Laurel Collins and Peggy Fieldler, to discuss project and review field site. 2. Field Work: (a) to position longitudinal profile distance stations and locating future cross sections; (b) to survey cross sections downstream of Capistrano box culvert, through pools and riffles at two stable reference sites; (c) survey associated stream profile at the two reference sites and downstream of the box culvert; (d) collect surface and subsurface sediment samples at the two stable riffle sites; and (e) document cross sections with photographs. 3. Plotting Data: Reduce, analyze, and graph data. Jerry Davis will reduce and plot profile data. Laurel Collins will reduce and plot cross sections. 4. Data Analysis: Sieve and weigh gravel samples and consult with reviewer. 5. Design Development: Review proposed plans by LC Lee and Assoc., and make additional recommendations for upstream segment. Develop conceptual design plans. 6. Design Plan: Meeting with Scott Holmes, SPCWC, and LC Lee & Assoc. to present findings and further develop conceptual restoration design.

Also important, and much less expensive at least in the short-term would be creating low-flow channels in culverts at other bridges upstream of Capistrano: Linda Mar, Oddstad, and the Horseshoe Pit bridge on the Middle Fork in San Pedro Valley County Park. A more long-term, but more expensive solution at each of these sites would be removal of each box culvert and replacement of each bridge with a wider span. The only cost for such we could estimate is the Horseshoe Pit Bridge in the park, for which we can assume the cost to be similar to a bridge we already replaced higher up in the system.

58 Other barriers exist in tributary watersheds. For example, most of Sanchez Fork is blocked by a substantial drop from a 6’ corrugated culvert under a church parking lot (Figure 19).

Figure 19. Sanchez Fork Barrier (photograph by Jerry Davis, 2002)

Other in-stream projects we assigned high priority to include a site (#10) where a serious toxic (creosote) retaining wall (see photo at 5660' in Volume 1) failure is happening at an old dam site. This site benefits from what would appear to be a relatively amenable situation: while the retaining wall protects homes very close to the creek on the south bank, on the north bank is a large property owned by the Alma Heights School, which is also looking for a creek enhancement project to use as an educational tool for its students. There is clearly room here, assuming we can count on the cooperation of landowners, for a highly beneficial and attractive in-stream project involving removal of the dam remnants and a restoration of meanders and riparian corridor system.

59 We are recommending a longitudinal profile and cross sections of the South Fork to assess the potential for adding approximately 3000’ of enhanced habitat, and barrier removal to reaches upstream. Hagar’s evaluation noted limitations in habitat on this fork, due to steepness; the excessive gradient of this fork is due to channelization and straightening, with a significant berm on the left bank separating the stream from a gravel road. This situation is creating erosion problems, threatened structures, habitat degradation and a greater potential for flooding downstream. As a result of 2002 meetings with the North Coast County Water District, which owns the South Fork subwatershed and leases most to the County Park, we have furthered the cooperative efforts of our Coalition with one of its important members, and plan to pursue joint projects. For example, we have agreed to pursue an assessment of channel conditions (longitudinal and cross-sectional) and erosion features along this reach. We are hopeful that this will lead to a corridor restoration plan for this reach, which has great potential for enhancing fish habitat. We also hope to work with the NCCWD to study sediment sources, of concern not only to fish but also to water supplies, and to evaluate (July 2002) the costs and benefits of future water diversions. An important factor in this analysis should be the benefits of water flows to fisheries.

While not a restoration project per se, we placed a very high priority on pursuing a feasibility study for an array of possible projects to address the North Fork 8' culvert outlet. This outlet was identified throughout the assessment as a major problem: as a source of extremely fast storm flows and the resultant bed and bank erosion problems downstream, and thus a source of significant fines to the water quality, and the well-documented poor water quality emitted at this site. Clearly these two problems must be addressed in some manner, but the situation is complex and problematic. A stormwater flow storage system, a filtration system, and various partial daylighting proposals have been put forth, but each will require considerably more study. Thus we have listed this as a high priority.

Installation of large woody debris (LWD) structures to enhance fish habitat is commonly used in streams with limited supplies. Our assessment, especially Volume 1, recommends instead using a management policy change: not removing LWD as it collects, currently a flood-control program pursued by the City of Pacifica. It is clear from our discussions with City personnel

60 that further study is needed to best effect a LWD program. The likely result of this study will be to identify suitable areas for specific LWD management procedures.

Other restoration projects given high priority include non-native invasive removal and replanting of the riparian corridor. We recommend that these projects include a significant volunteer component, and thoroughly involve creekside residents in installation and maintenance. Many creekside residents are highly interested in "doing the right thing" in their backyard – restoring native plants and at the same time enhancing the landscape for their own enjoyment – they just need a little help and guidance. Educational projects are also important, and probably the best way to improve water quality and limit the spread of invasive exotics. We hope to sponsor workshops and provide educational materials for creekside residents, and help our citizens to understand what it means to live in a watershed.

61 Table #2 Proposed Projects: Major Fish Impediments, Vegetation Gaps and Erosional Problems, San Pedro Creek, Pacifica

Initial Enhancement Method Potential I.D. Reach Priority Sites Benefits Problems Estimated Permits Sought Funders Cost Fish Impediments Impediment to juvenile and Replacement of fish ladder Department of adult steelhead rearing and and upstream concrete Water USACOE, Capistrano Restored longitudinal spawning habitat, eroding channel with step pool Resources, CDFG, 1 9* H Phase 1 connectivity to vitally $1,500,000 stream channel and adjacent system, shore bridge California DFG RWQCB, (Downstream) important steelhead run banks, canopy gaps, poor footings, stabilize (Emergency CEQA fish habitat streambanks Funds) Impediment to juvenile and adult steelhead rearing and Conduct field reconnaissance USACOE, Capistrano Restored longitudinal spawning habitat, eroding work, survey cross-section USACOE, $300,000- Department of 2 9* H Phase 2 connectivity to vitally stream channel and adjacent and longitudinal profile. CDFG, $400,000 Water (Upstream) important steelhead run banks, canopy gaps, poor Develop a conceptual RWQCB Resources fish habitat, sediment restoration design. erosion California USACOE, Linda Mar Coastal CDFG, 3 11* H Improved fish passage Shallow flows Install low-flow channel $5,000 Bridge Conservancy, RWQCB, DFG CEQA

Replace bridge, construction California USACOE, Reduced flooding, improved Inadequate to pass flood Adobe Street of downstream pool/run $400,000- Coastal CDFG, 4 5* L fish passage, enhanced flows of any serious Bridge complex, Restore riparian $450,000 Conservancy, RWQCB, habitat magnitude corridors DFG CEQA

Improved fish passage, California USACOE, Shallow flows and potential Oddstad provides rearing habitat Coastal CDFG, 5 13* H for greater impediment Low-flow channel $5,000 Bridge during extreme events on Conservancy, RWQCB, from downstream erosion mainstream DFG CEQA

62 Initial Enhancement Method Potential I.D. Reach Priority Sites Benefits Problems Estimated Permits Sought Funders Cost

Improved fish passage, California USACOE, Shallow flows and potential Oddstad provides rearing habitat Culvert removal and bridge Coastal CDFG, 6 13* M for greater impediment $1,000,000 Bridge during extreme events on replacement Conservancy, RWQCB, from downstream erosion mainstream DFG CEQA

Improved fish passage, California USACOE, Shallow flows and potential Horseshoe Pit provides rearing habitat Low-flow channel (short- Coastal CDFG, 7 15* H for greater impediment $5,000 Bridge during extreme events on term) Conservancy, RWQCB, from downstream erosion mainstream DFG CEQA

Improved fish passage, California USACOE, Shallow flows and potential Horseshoe Pit provides rearing habitat Culvert removal and bridge Coastal CDFG, 8 15* L for greater impediment $75,000 Bridge during extreme events on replacement Conservancy, RWQCB, from downstream erosion mainstream DFG CEQA Instream Projects

Reduced downstream erosion California USACOE, Feasibility study to consider and concomitant fine Peak flow issues, water Coastal CDFG, 9 11 H North Fork storage/ peak-flow reduction $25,000 sediment problems, quality Conservancy, RWQCB, project alternatives improved water quality, etc. DFG CEQA

Alma Heights Erosion on (opposite) California USACOE, Lengthening of channel, Restore meanders and School south bank at old dam site Coastal CDFG, 10 5H improved riparian habitat, riparian corridor, revetment $200,000+ creekside and toxic material used in Conservancy, RWQCB, flood water storage removal property revetment DFG CEQA California USACOE, Sanchez Lengthening of channel, Erosion and failing Restore meanders and Coastal CDFG, 11 7M Center improved riparian habitat, revetments on (opposite) riparian corridor, revetment $200,000+ Conservancy, RWQCB, Property flood water storage south bank removal DFG CEQA

63

Initial Enhancement Method Potential I.D. Reach Priority Sites Benefits Problems Estimated Permits Sought Funders Cost Restore meanders and widen California USACOE, Downstream Lengthening of channel, riparian corridor above Linda Coastal CDFG, 12 3L of Peralta improved riparian habitat, Flooding, degraded habitat $250,000 Mar Convalescent Home, Conservancy, RWQCB, Bridge Project flood water storage revetment removal DFG CEQA Ditched stream with associated poor habitat; Removal of berm & dam California USACOE, Enhance habitat and allow contribution to downstream structures; restoration of Coastal CDFG, 13 17 H South Fork for fish passage to areas of $150,000 flooding and sediment meanders and riparian Conservancy, RWQCB, potential habitat supply; fish passage barrier corridor DFG CEQA at old dam structure DFG, State USACOE, Inadequate staging area for Constructing tidally WRCB, CA CDFG, 14 1 H Creek Mouth Enhance steelhead habitat $250,000 anadromous fish influenced wetland Coastal RWQCB, Conservancy CEQA

LWD Study methods of LWD Enhance fish habitat with Degraded habitat, especially Existing City 15 ALL H Feasibility management and potential $25,000 CDFG LWD pools and resting areas permits Study installation

Non-Native Invasive Species N. Bank Restored riparian habitat, downstream of increased area and duration Capistrano Eradication of exotics, of shading, lowering of water Degraded habitat due to Avenue to the followed by high density $30,000- NFWF, 16 7/8 M temperatures, protection of invasion of non-native NA lower end of replanting of native riparian $35,000 RWQCB exposed banks against vegetation the Sanchez species erosion, improved water Art Center quality Property Eradication of exotics, Peralta to followed by high density $20,000- NFWF, 17 4M Improve canopy cover Canopy gaps NA Adobe reach replanting of native riparian $25,000 RWQCB species

64 Initial Enhancement Method Potential I.D. Reach Priority Sites Benefits Problems Estimated Permits Sought Funders Cost Provide most cost-effective Establish a comprehensive $250,000+ NFWF, 18 ALL H Entire creek approach to control of Continuing invasion NA NIS maintenance program (five years) RWQCB problematic exotics Improving habitat for native Invasive species and Ivy eradication, using an County Park species and decreasing the $5,000 + NFWF, 18 13-18 M disturbance of natural intensive volunteer NA area threats of invasive volunteers RWQCB riparian canopy cover eradication program propagation downstream Alma Heights NFWF, 19 6M to Sanchez Improve canopy cover/shade Major canopy gap Revegetation with natives $20,000+ NA RWQCB Nursery Water Quality California Non-point source sediment Water Upper Enhance water quality of 20 ALL M pollution from debris flows Sediment source analysis $120,000 Resources None watershed significance to salmonids and slope wash Control Board (205J) Coastal Entire Improve water quality, Acute toxic spills, loss of 21 ALL H Educational program $50,000 Commission, None watershed prevention of major fish kills young fish & eggs STOPPP, DFG Land Acquisition Severe bank erosion Storing flood flows, Coastal USACOE, North Fork downstream and associated Land purchase, daylight mitigating water quality Conservancy, CDFG, 22 19 H Terra Nova sediment pollution and fish creek, riparian corridor City-owned issues, steelhead and other Pacifica Land RWQCB, branch barriers; bacterial water restoration habitat improvement Trust (PLT) CEQA quality degradation Bank erosion on both USACOE, Upstream of Steelhead and other habitat Coastal banks, significant potential Land purchase, riparian CDFG, 23 12 H NF improvement, potential site $561,000 Conservancy, for future fish barrier at corridor restoration RWQCB, Confluence for Riparian Station PLT Oddstad Bridge CEQA School- Coastal Oddstad Storing flood flows, restoring Urban runoff flashy flows, Land purchase, riparian 24 NA H district- Conservancy, “ School site Red-legged Frog habitat landfill runoff corridor restoration owned PLT

65

5. REFERENCES

Ahnert, Frank. 1998. “Introduction to Geomorphology.” Arnold group. London.

Amato, Paul. 2002. Personal communication. (510-622-2429)

Bartram, J. and Helmer, R. 1996. Introduction. In Water quality monitoring-a practical guide to design and implementation of freshwater quality studies and monitoring programmes. E & FN Spon, London. pp. 1-8.

Chan, Christine. 2000. “The Functional Values of Urban Stream Restoration" Paper. San Francisco State University.

Dunne T. and L. B. Leopold. 1978. "Water in Environmental Planning" W. H. Freeman and Company. New York.

Eyre, B. and D. P. Pepperell. 1999. “A spatial intensive approach to water quality monitoring in the Rous River catchment, NSW, Australia.” Journal of Environmental Management. 56: 97 –118.

San Pedro Creek Watershed Coalition. 1999. San Pedro Creek Description (Early draft of a) Management Plan.

Titus, R. G., D. C. Erman, and W. M. Snider. “History and status of steelhead in California coastal drainages south of San Francisco Bay”. In preparation.

US Department of Agriculture. 1991. Soil Conservation Service. Soil Survey San Mateo County, Eastern Part and San Francisco County California Region. In cooperation with the regents of the University of California (Agricultural Experiment Station).

US Army Corps of Engineers. 1998. Final Detailed Project, Report Environmental Impact Report/Environmental Impact Statement San Pedro Creel Flood Control Project: Volume I: USACE San Francisco District and City of Pacifica, California.

Wilkinson, Nancy and Bernard Halloran. 2001. “San Pedro Creek Pollution. Tracking the health of the creek through Linda Mar” Pacifica Tribune. Wednesday, April 25, 2001.

66 6. CONTACT INFORMATION

Name Organization Address Phone Number E-mail Jerry Davis President, SPCWC 1119 Manzanita, Pacifica, CA 650-3596904 [email protected] 94044 Nancy Wilkinson Secretary, SPCWC 1119 Manzanita, Pacifica 650-3596904 [email protected] Bernard Halloran Chair Water Quality Committee, 32 Humboldt Ct, Pacifica 650-359-7191 [email protected] SPCWC Eulalia Halloran Vice-president, SPCWC 32 Humboldt Ct, Pacifica 650-359-7191 [email protected] Mike Vasey Chair Non-Native Species [email protected] Committee, SPCWC Christine Chan SPCWC Projects Coordinator 122 Hilton Ln, #3, Pacifica 650-355-1373 [email protected] Vivian Matuk SPCWC Coordinator 555 Brosnan Ct #1 650-878-8345 [email protected] Daly City, CA 94015 Patricia Delich SPCWC Board Member 650-359-5804 [email protected] Paul Jones SPCWC Board Member 1190 Manzanita Dr, Pacifica 650-355-4283 [email protected] Jeff Hagar Hagar Environmental Science 6523 Claremont Avenue 510-236-7366 [email protected] Richmond, CA 94805 Laurel Collins Watershed Sciences 1128 Fresno Avenue 510-524-8204 [email protected] Berkeley, CA 94707 Paul Amato San Francisco Regional Water 1515 Clay Street, Ste 1400 510-622-2429 [email protected] Quality Control Board Oakland, CA 94612 Scott Holmes Dept of Public Works, City of 170 Santa Maria Avenue, Pacifica 650-738-8660 Pacifica Kris Krow Dept of Public Works, City of 170 Santa Maria Avenue, Pacifica 650-738-8660 [email protected] Pacifica Chris Hunter Pacifica Tribune 59 Aura Vista 650-359-6666 [email protected] Box 1189, Pacifica Ann M. Crum San Francisco Regional Water 1515 Clay Street, Ste 1400 510-622-2474 [email protected] Quality Control Board Oakland, CA 94612 Carmen Fewless San Francisco Regional Water 1515 Clay Street, Ste 1400 510-622-2316 [email protected] Quality Control Board Oakland, CA 94612 Dave Sands Go Native Nursery

67 7. INDEX TO ASSESSMENT VOLUMES

Volume Page A Adobe Bridge II 12 Alder, Red (Alnus rubra) II 8, 14 Alkalinity III 99 Mean alkalinity values graph III 100 Alkalinity and electrical conductivity correlation III 125 Arroyos II 10

B Banks I 48-61 Bank Conditions I 50-51 Bankfull Widths I 52-53 Revetment Types I 56-59 Terrace Heights I 48-49 Blackberry, California (Rubus ursinus) II 8, 11, 12 Blue gum Eucalyptus II 16

C Canopy characteristics IV Table 8 Cape Ivy (Delairea odorata) II 8, 16 Capistrano bridge I 48 II 13 Climate I, III 5-7, 12 Annual Precipitation I 7 Cover Class Codes II 5 Coyote brush (Baccharis) II 10

D Dissolved Oxygen III 104 Mean dissolved oxygen graph III 109 Dogwood (Cornus sericeous) II 8, 13

E Elderberry, Red (Sambucus racemosa) II 8 Electrical Conductivity III 102 Mean electrical conductivity values III 105 Erosion I 60-62 Bank Erosion I 62 Landslide Erosion I 60-61 Enterococcus III 120

68 Mean Enterococcus graph III 121 Escherichia coli III 118 Mean Escherichia coli graph III 119 Estuarine II 11

F Fecal coliform bacteria III 116 Mean fecal coliform graph III 117 G Geology I, III 8, 13 Geology Map I, III 9, 14 H Hardness III 101 Mean hardness values graph III 103 Horsetail, Giant (Equisetum telmateia) II 8, 11

I Impervious Surface I Infestations of NIS II 6

L Landscape I 11 Landscape Change and Timeline I 11-35 Landscape-scale analysis of vegetation II 7 Landslide Erosion I 60-61 Longitudinal profile I 46-47 I 87-88

M Metals III 111 Middle Fork II 14-15

N Nettle, Hoary (Urtica dioica) II 8 Nitrates III 110 Nitrites III 110 Nitrogen Ammonia III 110 Non-native invasive species (NIS) II 2, 17-21 blue gum (Eucalyptus globules) II 8 cape ivy (Delairea odorata) II 8 cherry plum (Prunus cerasifera) II 8 Chinese honeysuckle (Lonicera japanica)1 II 8 English ivy (Hedera helix) II 8 fuchsia (Fuchsia magellanica) II 8 Himalaya berry (Rubus discolor) II 8 Monterey cypress (Cupressus macrocarpus) II 8 Monterey pine (Pinus radiata) II 8 periwinkle (Vinca major) II 8

69 poison hemlock (Conium maculatum) II 8 radish (Raphanus sativa) II 8 North fork I various II 14 III various

O Oddstad bridge II 14

P Pampas grass II 9 Peralta Bridge II 11 pH III 96 Mean pH water values graph III 97 Phosphorus III 110 Pools I 70-75 Number and percent of different pool volume classes I 70 Number and percent of different pool volume graph I 71 Number of pools per volume class per reach I 72 Number of pools per volume class per reach graph I 72 Causes I 75

R Rapid Assessment Methods II 3 Reaches I 36, 52 II 10-16 Rearing capacity IV 17 Relative Importance Value (RIV) II 4 Revetments I 56-57 Length of different types I 56 Length of different types graph I 57 Riffles IV Table 10 Riparian habitat restoration II 2 Riparian vegetation II 2 Riparian Vegetation Survey II 5 Rubus ursinus II 8

S Satellite imagery II 6 Sediments I Mechanism and Amount of Sediment Supply I 60 Normalized Sediment Supply I 63 Distribution of different sizes of sediments I 66-69 Species II 7 Steelhead trout IV Disturbance IV 18 Depth Selection by Young-of-year trout (less than 4”) IV Table 4 Depth Selection by Yearling and older trout

70 (more than 4”) IV Table 5 Exploitation IV 19 Habitat requirements IV 23 Steelhead assessment IV 7-21 Life history IV 23 Limiting factor assessment IV 14 Migration barriers IV 15 Observed trout 2001 IV Table 3 Previous steelhead trout assessment reports in San Pedro Creek IV 3-4 Shelter complexity IV Table 6 Shelter components IV Table 7 Steelhead assessment in San Pedro Creek mainstem IV 7 Steelhead assessment in San Pedro Creek middle fork IV 10 Steelhead assessment in San Pedro Creek south fork IV 12 Steelhead assessment in San Pedro Creek Sanchez fork IV 13 Steelhead assessment in San Pedro Creek Shamrock fork IV 13 Streams Stream Classes I 86-88 Stream discharge III 93 Stream discharge and water level graph III 95 Stream discharge and electrical conductivity correlation III 124 Stream discharge and pH correlation III 124 Stream discharge and turbidity correlation III 124 Stream Flow I, IV 5-7,17 Streamline Graphs I 104 Substrate characteristics IV Table 9

T Thimbleberry (Rubus parviflorus) II 8, 11 Topography I 2 Total coliform bacteria III 111 Mean total coliform values graph III 114 Total Suspended solids III 92 Turbidity III 92

U U.S. Vegetation Classification System II 2

V Vegetation III 16 upland II 10 Vegetation Polygons II 6 Volatile Organic compounds III 111

71 W Water Temperature III, IV 83, 6-7 Mean water temperature values graph III 84 Water temperature and electrical conductivity correlation III 123 Water temperature and dissolved oxygen correlation III 124 Water Quality III Water Quality sampling sites map III 66 Watershed embeddedness IV Table 11 Watershed and Sub-watershed III 8-12 Watershed Map I 3 Willow, Arroyo (Salix lasiolepis) II 8, 11 Willow, Shining (Salix lucida ssp. laevigata) II 8, 11 Willow, Sitka (Salix setchensis) II 11 Woody Debris I 76 Number and percent of Large Woody Debris Types I 76 Types graph I 77 Number of Large Woody Debris per reach I 78 Debris jam characteristics I 80 Debris jam characteristics graph I 81 Recruitment process I 82-85

72 .. ___,,__.;·-""

I"

I

ROUTE 1-CALERA PARI

EXISTING CONDITIONS

ENGINEERING • PLANNING • SURVEYING GEOGRAPHIC EXTENT OF WATERS ! OF THE U.S., I INCLUDING WETLANDS IN THE PROPOSED L. C. LEE & ASSOCIATES, 383 A VINTAGE PARK DRIVE TRAMMEL CROW ROCKAWAY BEAC8 DEVELOPMENT 221 1st Avenue IJ., IJA 9BII9 FOSTER CITY, CAUFORNIA 9«0.4 PACIFICA, CALIFO NIA (phon"), crnx> FAX I Sheet 1 of 1 United States Department of the Inte:IMCEIVED FISH AND WILDLIFE SERVICE Sacramento Fish and Wildlife Office DEC 19 2000 2800 Cottage Way, Room W-2605 Sacramento, California 95825-1846 CiTY MANAGER

IN REPLY REFER TO: 1-1-00-F-229 December 18, 2000

Mr. Calvin Fong Chief, Regulatory Branch U.S. Army Corps of Engineers San Francisco District 3 33 Market Street San Francisco, California 94105-2197

Subject: Formal Endangered Species Consultation on the Proposed Pacifica Police Station, California State Highway 1, Pacifica, San Mateo County, California .

Dear Mr. Fong:

This document transmits the U.S. Fish and Wildlife Service's (Service) biological opinion on U.S. Army Corps of Engineers (Corps) request for formal consultation for the proposed Pacifica Police Station on Highway 1 in San Mateo County, and project effects on the federally endangered San Francisco garter snake (Thamnophis sirtalis tetrataenia)(garter snake) and . federally threatened California red-legged frog (Rana aurora draytoniz} (red-legged frog) conference on the proposed critic& habitat for this species. This biological opinion is provided in accordance with section 7 of the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.) (Act). Your August 13, 2000, request to initiate consultation on the garter snake and red- legged frog was received in our office on August 21,2000.

This biological opinion is based on information provided in: (1) The July 1, 2000 Pacifica Police Station Ecosystem Restoration Plan (Restoratio'n Plan); (2) the September 12,2000 Revised Biological Assessment for the Red-legged Frog (Rana aurora draytonii) and San Francisco garter snake (Fhamnophis sirtalis tetrataenia) for the Construction Activities Associated with the Proposed Police Station, Pacifica CA; (3) a September 5, 2000 meeting and site visit; (4) a meeting on November 17,2000 between representatives of the Service, City of Pacifica (Pacifica) and L.C. Lee and Associates (LCLA); and (5) information in Service fi_les. A complete administrative record is on file at the Sacramento Fish and Wildlife Office (SFWO). Mr. Calvin Fong 2

Consultation History

July 17,2000: The Service received a letter dated July 13,2000, from the Corps requesting concurrence that the proposed project would not affect red-legged frogs, or in the alternative append the project to the programmatic biological opinion for red-legged frogs.

August 3, 2000: Sheila Larsen of my staff met with representatives of Pacifica to discuss the project and develop minimization measures to reduce impacts resulting from the proposed project. The Service received a copy of the Pacifica Police State Initial Study/Mitigated Negative Declaration and a copy of the Pacifica Highway 1 Calera Parkway Project/CEQA Initial Study/NEPA Environmental Assessment dated July 2000.

August 4, 2000: The Service responded (Service file no.: 1-1-00-I-2522) to the July 13,2000 letter stating the project would adversely affect both garter snakes and red-legged frogs.

September 11, 2000: The Service received a letter from Pacifica stating that they were expanding the environmental analysis and preparing an Environmental Impact Report, including an amended Biological Assessment.

November 17,2000: Sheila Larsen met with L.C. Lee and Pacifica staff to finalize the conceptual wetland design, including the laying back of the creek bank and design of the macrodepression areas.

BIOLOGICAL OPINION

Description of Proposed Action . . The proposed project consists of: (1) constructing buildings, facilities, and parking lots necessary for a police station; (2) constructing an access road to the station that spans Calera Creek and crosses the restoration area; and (3) restoring portions of waters/wetlands and the riparian zone of Calera Creek to minimize impacts to garter snakes and red-legged frogs.

Project Site

The project site is located on an old motel site north of the Reina del Mar intersection and east side of Highway 1 along a highly degraded reach of Calera Creek. Calera Creek was bulldozed in the 1960's to clear it for flood control, and the material was deposited as a berm on the north bank of the creek. During operation of the motel, which was destroyed by fire in the 1970's, the owners deposited fill near the Calera Creek channel. Fill material at the site is, on average, two feet thick, and it has been graded repeatedly to eliminate microtopographic variation typical of alluvial valleys. Other fill placement operations in the riparian zone are evidenced by hwllinock areas in the flood plain. The berms and hummocks are now overgrown with a variety of native . Mr. Calvin Fong 3

(e.g:, Rubus ursinus, Salix lasiolepis, Urtica dioica)and non-native (e.g., Senecio mikanioides, Eucalyptus globulus, Rubus discolor) plant species. Pacifica has also utilized the site as a lay down area for their projects. ·

Immediately north and east of the proposed police station site is a steep hillside that rises sharply to join Sweeny Ridge at its highest point. This hillside is dominated by native and naturalized grasses, with a few isolated coyote bush (Baccharis pilularis). At the eastern boundary is a row of mature Monterey cypress trees (Cupressus macrocarpa) and a chain link fence. An·elementary school is on the adjacent property to the east, and Calera Creek enters the project site through a large culvert under the school site. To the south is a private business. Both of these facilities are outside the project boundaries. The Laguna Salada Union School District owns a portion of the southwest comer (Figtite 1) that had previously been ic;lentified as part of the project site.

Calera Creek is an intermittent stream with a 1,048-acre (1.64 square miles) drainage area that flows into the Pacific Ocean north of Rockaway Beach. It is a third- to fourth-order stream set in a valley characterized by steep coastal hills, transitional footslopes, alluvial terraces and valleys, marine terraces, mudflats, dunes, and ocean beaches. Average annual flow of the creek is 2.33 cubic/feet/second at the project site (Baker Engineering 1993 in L.C. Lee, 2000).

Police Station Facilities

Pacifica proposes to construct a new police station on the approximately 4 acre site. The police station will be 20,000 square feet, and situated entirely on the upland portion of the site. Parking lots will be located on the east and west side of the building with the main lot· on the east side (Figure 1). The parking lot will have 60 slots A berm will be placed between the restoration site and the police station parking lot.

Access Road

The access road will enter the project site from the south side of Calera Creek, through the riparian zone, to the upland area on the site (Figure 2). The access road enters from the south side to allow a direct route to southbound Highway 1. Egress to southbound Highway 1 from the west side driveway is not possible because of a k-rail median barrier that separates the north and south bound lanes.

The flat surface of the access road will be constructed with bituminous paving on top of a graded gravel sub-base. It will be approximately 25 feet wide. In addition, 2:1 (horizontal:vertical) sideslopes will be required from the flat road surface, resulting in a 45-foot wide road "foot- print." The road design includes two 36-inch culverts under the access road to allow wildlife movement under the access road. The access road will span the existing Calera Creek channel at an elevation that is at least two feet above the anticipated 100 year peak flow event (i.e., Mr. Calvin Fong 4

approximately 800 cubic/feet/second). Therefore, there will be no impacts to Calera Creek below ordinary high water.

The roadway will be constructed through the narrower portion of waters/wetlands on the site, thereby minimizing impacts waters/wetlands from the roadway. Construction of the roadway also · requires that 0.06 acre of dense riparian vegetation (i.e., Salix lasiolepis) be cleared (Figure 1). The proposed access road will impact a total 0.16 acre wetland/riparian habitat.

Restoration Plan

The restoration plan for the proposed police station focuses on restoring ecosystem function in four broad categories to the waters/wetlands adjacent to Calera Creek: (1) hydrology; (2) biogeochemistry; (3) plant community; and (4) faunal habitat. For a full description of the proposed restoration plan, refer to the Restoration Pl(ln for the police station project (LCLA 2000). However, some restoration components have been altered from the Restoration Plan as a result ofthe November 17,2000

The wetland restoration includes the following features: A palustrine emergent plant community - (i.e., herbaceous perennials) in two.depressions at the east end of the site that will support seasonal ponds surrounded by native sedges, rushes and grasses; and removal of non-native trees, such as the escaped ornamentals, Monterey pines (Pinus radiata) and Casuarina (Casuarina sp.), found on the north side of the property. Removal of these trees will be in addition to the removal of non-native species within the riparian corridor.

The Restoration Plan (L.C. Lee 2000) left the existin.g berm and proposed hand excavation of wide "ports" within the berm to allow overflow from Calera Creek to flood into the restoration · f area. Off channel wood/floodplain logjams will be constructed for habitat complexity. In addition, several shallow depressions were to be constructed, .two at the east side of the restoration site and one on the south side. · However, as a result of the November 17th meeting Pacifica agreed to lay the creek banks back allow a direct connection between the creek and its floodplain. The revised restoration plan proposes a grading slope·of7:1 and the creation of macrodepressions, which will be designed in a manner to hold water for as long a.S possible given the limited water flow through the site. The purpose of macrodepressions are to provide foraging habitat for red-legged frogs and possibly breeding habitat in high flow years. (Figure 3). The · changes in the restoration plan that resulted from the November 17th meeting will have greater { wetland impacts that the original plan, however, those impacts are expected to be offset by macrodepressions that will hold water for a longer time, ultimately benefitting red-legged frogs. ( The proposed project will impact 0.55 acre of waters/wetlands and 0.44 acre of riparian zone and 1 restore 0.98 acre. L__ Pacifica will institute a monitoring program to assess the progress of the waters/wetlands and riparian ecosystem restoration project at the project site. Yearly monitoring reports will be Mr. Calvin Fong 5 prepared for a five-year period after the restoration project is completed. Monitoring reports will document the progress of the hydrologic, biogeochemical, plant community, and faunal support/habitat project targets and standards outlined in the Restoration Plan (LCLA 2000). The faunal support/habitat section will include a yearly survey for five years for the California red- legged frog by a Service-approved biologist.

Conservation Measures

1. Construction will occur generally during the dry season to prevent erosion problems. No construction will occur in the water/wetland area during late winter and spring.

2. Stormwater from the buildings and parking lots will flow through grit removal and oil/water separators (e.g., compost filters or similar) located at each catch basin on the site. Secondary treatment of the stormwater will occur as the water passes through a minimum 10-foot length filled with 4.to 8-inch rock and then through a subsequent 10- foot minimum long grass filter strip. The restoration area will act as a tertiary system prior to entering the Calera Creek riparian zone (Figure 4).

3. The trash receptacle will be placed at the north edge of the parking lot away from existing waters/wetlands.

4. All outside lighting for the building parking lot will be directed away from the waters/wetlands.

5. Prior to any grading an exclosure fence will be installed. The exclosure fence will be constructed of 4-foot high plywood board fence supported with "T" posts and buried · approximately 12 inches. Prior to installation a Service approved biologist will search the area and remove all red-legged frogs to a Service approved location.

6. After construction completion a permanent barrier to prevent access by garter snakes and red-legged frogs to the road and police station area will be constructed to replace the plywood exclosure fence. The permanent barrier will be buried a minimum of six inches and be a minimum height of 24 inches.

7. Appropriate best management practices (BMPs) will be implemented throughout the construction process to avoid and minimize any water quality degradation as a result of grading operations on the site. In addition, water quality monitoring will occur to help the City target problem areas on the site that require additional BMPs to avoid the dlscharge of poor quality stormwater to waters/wetlands.

8. Control bullfrogs by extirpating to the extent possible any bullfrog populations tliat may . establish in the Calera Creek system. Mr. Calvin Fong 6

9. All workers on the police station site will be briefed by LCLA on the environmentally sensitive nature of the project. The briefing will include specific instruction on protection of red-legged frogs, with appropriate directions to avoid impacts to the threatened species. , ·

Status of the Species

San Francisco garter

The garter snake was listed as a Federal endangered species in March 1967 (32 FR 4001). The garter snake is an extremely colorful snake. It is identified by a burnt-orange head, yellow to a greenish-yellow· dorsal stripe edged in black, and its red lateral stripe which may be continuous or broken with black blotches and edged in black. The belly color varies from greenish-blue to blue. Large adults can reach three feet in length. -

The garter snakes' preferred habitat is a pond with a densely vegetated edge near an open hillside - where it can sun. itself, feed, and find cover in rodent burrows. They are extremely shy, difficult to locate and capture, and quick to flee to water or cover when disturbed. Adult snakes may seek cover in rodent burrows during summer months when ponds may dry. On the coast, snakes hibernate during the winter, but further inland, if the weather is suitable, snakes may be active year round. Although highly vagile, adults spend considerable time after emergence in their hibemacula. They have been seen breeding at entrances to these burrows shoitly after emergence from hibernation {Keel, pers. comm.), and may spend the majority of each day during the active season in the same burrows. Garter snakes breed in the spring or late fall and bear live young from May through October, with an average litter size of 12-18 (Stebbins 1985).

Although primarily a diurnal species, captive snakes housedin outside enclosure were observed foraging at night on warm evenings. Adult snakes feed primarily on frogs, and may also feed on · juvenile bullfrogs. In laboratory studies, Larsen (1994) fed adult garter snakes second year ·tadpoles and found that only the largest adults could eat and digest the tadpoles; smaller adults regurgitated partially digested tadpoles, apparently unable to fully digest them. Larsen (1994) also observed that when these smaller adult snakes were fed bullfrogs and frogs of comparable size, they were .unable to hold and eat the bullfrogs although they had no trouble with the frogs. Newborn and juvenile garter snakes depend heavily upon Pacific treefrogs (Hyla regilla) as prey (Larsen 1994), and young snakes may not survive if they are unavailable.

Many of the threats that led to the listing of the garter snake in 1967 continued to impact the species in 1985 when the Recovery Plan was written.. These included loss of habitat from agricultural, commercial and urban development and collection by "reptile fanciers and breeders" (Service 1985). Mr. Calvin Fong 7

The historical threats to the species remain, but there are now additional threats to the species, such as the documented decline of the frog (an essential prey species) and the introduction of bullfrogs into garter snake habitat. Bullfrogs are capable of preying on both garter snakes and frogs. Extirpation of frogs in garter snake habitat is likely to cause localized extinction ofgarter snakes.

California red-legged frog

The red-legged frog was federally listed as threatened on May 23, (61 FR 25813) effective June 24, 1996. A detailed accotmt of the taxonomy, ecology, and biology of the red..:legged frog is presented in the Draft Recovery Plan for the California Red-legged Frog (Rana aurora draytonii) (Service 2000). Additional information can be found in the Proposed Designation of critical Habitat for the California Red-Legged Frog (Rtina aurora draytonii); Proposed Rule (50 CPR 17, p. 54892-54932).

This species is the largest native frog in the western United States (Wright and Wright 1949), ranging from 4 to 13 centimeters (1.5 to 5.1 inches) in length (Stebbins 1985). The abdomen and hind legs of adults are largely red; the back is characterized by small black flecks and larger irregular dark blotches with indistinct outlines on a brown, gray, olive, or reddish background color.

The largest densities of red-legged frogs currently are associated with deep pools with stands of overhanging willows and an intermixed fringe of cattails (Typha latifolia) (Jennings 1988). However, red-legged frogs also have been found in ephemeral creeks and drainages and in ponds that may or may not have riparian vegetation. Red-legged frogs disperse upstream and downstream of their breeding habitat to forage and seek sheltering habitat. Sheltering habitat for red-legged frogs potentially includes all aquatic, riparian, and upland areas within the range of the species and any landscape features that provide cover, such as existing animal burrows, boulders or organic debris such as downed trees or logs, and industrial debris. Incised stream channels with portions narrower than 18 inches and depths greater than 18 inches also may provide important summer sheltering habitat. Accessability to sheltering habitat is essential for the survival of red-legged frogs within a watershed and can be a factor limiting frog population numbers and survival. During winter rain events, juvenile and adult red-legged frogs are known . to disperse up to 1-2 km (Rathbun and Holland, unpublished data, cited in Rathbun et al. 1991).

Several researchers in central California have noted the decline and eventual disappearance of red- legged frog populations once bullfrogs became established at the same site (L. Hunt, in litt. 1993, S. Barry, in litt. 1992, S. Sweet, in litt. 1993). This has been attributed to both predation and competition. Twedt (1993) documented bullfrog predation ofjuvenile northern red-legged frogs, and suggested that bullfrogs could prey on subadult red-legged frogs as well. In addition predation, bullfrogs may have a competitive advantage over red-legged frogs:. bullfrogs are larger, possess more generalized food habits (Bury and Whelan 19S4), possess an extended Mr. Calvin Fong 8

breeding season (Storer 1933) where an individual female can produce as many as 20,000 eggs during a breeding season (Emlen 1977), and larvae are unpalatable to predatory fish (Kruse and Francis 1977). In addition to competition, bullfrogs also interfere with red-legged frog . reproduction. Both California and northern red-legged frogs have. been observed in amplexus with (mounted on) both male and female bullfrogs (Jennings and Hayes 1990, Twedt 1993, M. Jennings, in litt.1993, R. Stebbins in litt. 1993).

Traffic can have a negative effect on amphibian species. Genetic analyses have found that common frogs (Rana temporaria) in urban areas are more genetically distinct than those found in rural areas (Hitchins and Beebee 1997}, and highways isolate common frog populations (Reh and Seitz 1990). Survival rates of common toads (Bufo bufo) decreases to 50 percent with 24 to 50 cars per hour (Kuhn, 1987 in Reh and Seitz 1990}, but survival can also decrease to 0 percent with 26 cars per hour (Heine, 1987 in Reh and Seitz 1990). Amphibians can be further impacted by development of watersheds by increasing the amount of impervious surfaces causing runoff of sediments, pesticides and heavy metals such as hydrocarbons (U.S. Environmental Protection Agency 1993. These deleterious materials causes a decline in water, quality which may impact red-legged frogs.

Red-legged. frogs are adapted to a highly variable climate that can alternate yearly between very wet and extreme drought conditions. In response to this variability, in wet years frog reproduction is high and more sites become occupied by dispersing young frogs. In drought years populations may decline and previously occupied sites are no longer inhabited. Therefore!, it is important to preserve areas that may be unoccupied as they may become so other years.

Proposed Critical Habitat

On August 31, 2000, a proposed rule designating critical habitat for the red-legged frog was published in the Federal Register (65 FR54891; Service 2000a). Calera Creek is not within the proposed critical habitat designation for red-legged frogs.

Environmental Baseline and Status of the Species in the Action Area

California Red-legged Frog

The environmental baseline used in this analysis includes past and ongoing impacts of Federal, State, Tribal, and private actions and other human activities in the vicinity of the project that have impacted, or are impacting the listed species.

Red-legged frogs have been extirpated or nearly extirpated from more than 70 percent of their historic range. Historically, this species was found throughout the Central Valley and Sierra Nevada foothills. As of 1996, red-legged frogs were known to occur in approximately 240 streams or drainages from 23 counties, primarily in central coastal California, Monterey, San Luis Mr. Calvin Fong 9

Obispo, and Santa Barbara counties support the largest extent of currently occupied habitat. The · most secure aggregations of red-legged frogs are found in aquatic sites that support riparian and aquatic vegetation and lack non-native predators. Several researchers in Central California have noted the decline and eventual local disappearance of red-legged frogs in systems supporting bullfrogs (Jennings and Hayes 1990), red swamp crayfish (Procambarus clarkii), signal crayfish (Pacifastacus leniusculu), and several species of warm water fish including sunfish (Lepomis spp.), goldfish (Carassius auratus), common carp (Cyprinus carpio), and mosquitofish (Gambusia affinis) (L. Hunt, in litt. 1993, S. Barry, inlitt. 1992, S. Sweet, in litt. 1993). Habitat loss, non-native species introduction, and urban encroachment are the primary factors that have adversely affected the red-legged frog throughout its range.

The draft recovery plan for the red-legged frog identifies eight Recovery Units. Within each Recovery Unit, core areas have been delineated and represent areas of moderate to high red- legged frog densities and are identified as areas where recoveryactions will be focused. This project is located within a Core Area of the Central Coast Recovery Unit, which includes western San Mateo and Santa Clara Counties, and portions of Santa Cruz, Monterey, and San Luis Obispo Counties.

The Core Area extends from Crystal Springs Reservoir west to Half Moon Bay and Pacifica. Within this Core Area, red-legged frogs historically bred in sag ponds which were common in this area. However, few sag ponds remain as they have been filled for urban development. Lack of available breeding sites within the Core Area has lead to the decline of the red-legged frog.

The Service issued a biological opinion to the Corps addressing the impacts of the Calera Creek Water Recycling Plant and Wetland Restoration Project (Service file no.: 1-1-96-F-163) (Recycling Plant), located on the west side of Highway 1 from the project site. The Recycling ·r Plant included realigning and restqring Calera Creek, as well as constructing two new ponds to replace two quarry ponds that had previously been drained and filled without incidental take . authorization. The restoration portion restored approximately 17 acres of waters/wetlands in the new stream channel. The two ponds total approximately 6,800 square feet. Red-legged frog -surveys conducted in 1999 found frogs breeding within the new ponds and Calera Creek. If is believed that these ponds may have been recolonized, in part, from red-legged frogs that moved from Laguna Salada to Calera Creek over uplands commonly known as Mori Point The Recycling Plant site, however, has experienced anjncrease in the feral cat population (S. Holmes, pers. com.). This may be a result of denser riparian which provides cover, an increased prey base from nesting birds or feral cat feeding stations. Feral cats are known to feed on bullfrogs and, likely to feed on red-legged frogs and garter snakes.

During fall of 2000, 1OS acres of Mori Point was purchased by The Trust for Public Lands for the purposes of maintaining open space. Red-legged frogs found in Laguna Salada and the lower section of Calera Creek may move up the Calera Creek watershed and disperse to Crystal ,Mr. Calvin Fong 10

Springs, San Pedro Creek, and Shamrock Ranch, and vice versa, thereby providing genetic interchange between populations found in this portion of the Central Coast Recovery Unit.

The Service issued a biological opinion dated March 27, 1997, to the Corps for the San Pedro Creek Flood Control Project (Service file no.: 1-1-96-F-164). Project construction began in the fall of2000. The project involves the reconfiguring and restoration of the San Pedro Creek from below the Adobe Drive bridge to the Pacific Ocean. The project included widening the floodplain, recreating sinuosity, backwaters arid removal of instream barriers. After construction the area will be planted with native vegetation. This project is expected to provide habitat for red-legged frogs.

On December 14,2000 the Service issued a biological opinion (Service file no.: 1-1-00-F-92) to the Federal Highway Administration (FHWA) for the impacts of construction a permanent new highway to bypass the Devil' s Slide portion of California State Highway 1. Proceeding south from Pacifica, the new alignment will depart from the existing Highway 1 and bridge a small valley at Shamrock Ranch approximately 0.5 km (0.3 mile) south of Linda Mar Boulevard in Pacifica. The tunnel would pass through San Pedro Mountain approximately 0.4 km (0.25 mile) inland of the existing highway. Project construction will begin during the summer of2001. FHWA will construct a new pond at Shamrock Ranch and try to obtain an easement for the two existing ponds. The easement area will be managed for red-legged frogs.

After the 1997-98 storms the Corps issued a regional general permit to authorize flood control work on Milagra Creek, north of the project site. Approximately 1, 730 feet of creek constituting 0.43 acre of wetland was filled and 0.4 acre of wetland was restored. Incidental take authorization was not requested by the Corps for this project and, therefore, the project was not reviewed by the Service. The Service does not know if unauthorized take of red-legged frogs may have occurred during this project. ·

San Francisco garter snake.

The garter snake population at the Pacifica quarry, where the Recycling Plant Project site is located, was thought to be made up of snakes migrated over the Mori Point saddle from Laguna Salada. Year-round water in Calera Creek and the quarry ponds allowed for a sustained red-legged frog population. Red-legged frogs and Paciijc treefrogs provided prey for all year- classes of garter snakes. In August of 1989, contractors for the quarry owner, Mr. William Bottoms, drained the quarry ponds by breaking the dam with a bulldozer thereby suddenly releasing the water into· Calera Creek. The contractors filled the quarry ponds, disced the surrounding grasslands, and removed vegetation along the banks of Calera Creek. A California Department ofFish and Game Warden and Ms. Sheila Larsen, at that time she was not a Service employee, condtiCted an intensive search for gart:er snakes and did not find any, although several snakes of other species were found dead and one dead red-legged frog was found in a bulldozer track. It was assumed that all garter snakes and red-legged frogs that retreated to the pond for Mr. Calvin Fong 11 protection were killed when the water was released. California red-legged frogs had been observed upstream and immediately west of Highway I in Calera Creek, and that section remained undisturbed from the bulldozing and discing activities.

In spring of I996, Dr. Samuel McGinnis conducted a trapping study to determine whether garter snakes were in the area, but the survey came up negative. However, with the recolonization of the ponds created for the Recyling Plant as described above, and reported sightings of garter snakes in the Laguna Salada area, it is believed that garter snakes still exist in that area, albeit in low numbers. In addition, a term and condition of the biological opinion for the Recyling Plant provides the Service with the ability to reintroduce garter snakes into the Recycling Plant restoration area.

Throughout the range of the species, and specifically in Pacifica and at Crystal Springs Reservoir, we consider the status of the garter snake to be tenuous because of activities that continue to erode the.baseline of the garter snake. Loss of pond habitat at Crystal Springs Reservoir and reservoir management has reduced that population to very low numbers reducing the likelihood of garter ·snakes dispersing from Crystal Springs into the Calera Creek watershed. Also, as stated above, the. destruction of the quarry ponds most likely reduced the population at Calera Creek to - extremely low numbers. When a population drops to very few individuals and involves a species that has a high mortality of young prior to reproductive age, the ability of the population to rebound is compromised. Although surveys have not been conducted, the few incidental sightings indicate that the population has not rebounded from that _incident.

Effects of the Proposed Action

The proposed police station project has several possible actions that will have direct or indirect impacts on the garter snake and the red-legged frog. No directed surveys for garter snakes or red-legged frogs have been performed on the proposed police station site. within the past 10 years. However, red-legged frogs have been confrrmed to utilize the habitat provided in the Recycling Plant restoration site (Davidson I999 in L.C. Lee, 2000). Calera Creek provides a direct surface water connection between proposed project site, and the Calera Creek restoration site through a large culvert passing under Highway I. Therefore, it is reasonable to assume that garter snakes and red-legged frogs could migrate from the Calera Creek restoration site upstream through the culvert to utilize the I.05 acres of waters/wetlands and dense riparian vegetation in and around Calera Creek on the proposed project. Although an exclosure fence will be constructed prior to and after construction, it remains possible that garter snakes and red-legged frogs may enter the project site through rodent burrows passing under the fence and opening onto the project site.

Possible actions that may have direct effects include: (1) loss of habitat habitat and hibernaculum resulting from the police station and parking lot; (2) construction of the access road; (3) construction of a spanning bridge over Calera Creek; ( 4) construction of the access road; ( 5) restoration of 0.98 acre of waters/wetlands and riparian areas; and (6) mortality or injury of garter Mr. Calvin Fong 12 snakes and red-legged frogs that may get through the permanent exclosure fence and be killed by vehicles on the road. Possible indirect actions that may have effects include: (1) higher traffic in the area sUrrounding Calera Creek; (2) temporary elevations in water turbidity and/or pH due to construction; and (3) some microclimate variation due to the new access road. Effects are discussed by each proposed action below.

Direct Effects

Direct effects include the potential for harassment, injury and/or mortality ofjuveniles and adults. Removal of vegetation from the bank may kill garter snakes and red-legged frogs that may remain in the riparian vegetation and were not found during removal efforts. Earthmoving equipment required for the restoration project may crush and kill garter snakes and red-legged frogs that remain within the project site or that inadvertently enter the restoration site. Until the restoration site is completely restored, garter snakes and red-legged frogs that enter the restoration site may not have the cover necessary to escape predators.

After project construction, garter snakes and red-legged frogs that inhabit the restoration area may be affected by the noise and vibration of traffic entering and leaving the police station. Although a fence will be erected to keep garter snake and red-legged frogs off the access road and parking lots, garter snakes and red-legged frogs may somehow enter the road and parking lot and be crushed and killed. Garter snakes and red-legged frogs that get through the fence may be unable to return to the restoration site and become desiccated from lack ofwater.

Construction of Buildings and Parking Lot

Construction of the police station and parking lot will result in a permanent loss of upland habitat for garter snakes. Loss of upland refugia will result in garter snakes having to travel greater distances between retreat areas and foraging areas, which could expose them to greater levels of predation by feral cats and raptors.

Spanning Bridge Over Calera Creek

The construction of a spanning bridge will: ( 1) remove an approximately 45-foot wide section of riparian vegetation; (2) create permanent shade over one portion of the creek; and (3) increased human presence (e.g., vehicles, pedestrians, bicycles, etc.) over and around the creek. The bottom elevation of the bridge is designed to be two feet higher than the I peak flow, so the bridge should not impede higher flows. Shading of the creek may decrease use of that portion of the creek by garter snakes and red-legged frogs for basking. For aging opportunities of red- legged frogs may decrease because cooler temperatures may decrease the number of insects. Mr. Calvin Fong 13

Construction of the Access Road

Construction of the access road will require that vegetation be cleared, and fill placed in the waters/wetlands and dense vegetation around the creek channel. During construction, garter snakes and red-legged frogs likely will be frightened away from·the area due to noise and vibration. In addition, it is possible that individual garter snakes and red-legged frogs may be killed as fill is placed, vehicles enter the area, and/or during the hand clearing operation.

The design of the road includes two 36-inch culverts under the road to allow for surface water connection, and garter snakes and red-legged frogs to pass under the road. If these culverts are not maintained, debris may build up to an extent that will inhibit or physically block the ability of garter snakes and red-legged frogs to pass through the culverts.

Restoration Project

The restoration project is intended to have a long-term beneficial impact to garter snakes and red- legged frogs. The restoration project will provide vegetative cover that provides feeding, li sheltering, and possibly breeding habitat. The restoration project will also provide suitable habitat- that will allow garter snakes and red-legged frogs to move from Recycling Plant restoration site up into the watershed toward Crystal Springs to the east, San Pedro Creek and Shamrock Ranch to the south providing exchange of genetic material between populations.

During the restoration construction phase, it is possible that individual garter snakes and red- legged frogs may be injured or killed during grading operations. Garter snake's and red-legged frogs may not be discovered in preconstruction surveys or penetrate the barrier fence and enter the project site.

Traffic On the Access Road

The access road will have the indirect effect by increasing human presence in and near garter snake and red-:legged frog habitat. Although garter snakes and red-legged frogs should be precluded from the road by the exclosure fencing, the fence will alter their movement patterns by preventing directional movement and causing them to go along the fence instead of their original movement path. Remaining close to the fence or reversing direction may increase risk of predation from exposure and inability to escape predators.

Untreated runoff from the access road may increase hydrocarbon concentrations in the surrounding habitat This may impact developing eggs and tadpoles, and reduce survivability. Decreased water quality may also decrease insect prey available to red-legged frogs reducing fitness of individual red-legged frogs. Garter snakes feeding on red-legged frogs with increased hydrocarbon concentrations in their tissues may also be adversely affected. Mr. CalvinFong 14

Temporary Elevation of Turbidity and/or Change in pH due to Construction

Project construction may result in discharges of turbid or altered water pH levels above or below background levels) to Calera Creek. These potential impacts to water quality could alter feeding and/or breeding ability of garter snakes and red-legged frogs.

Microclimate Modification Along the Access Road

Construction of the access road will disrupt vegetation continuity in the riparian zone of Calera Creek. The access road will create an "edge" along which temperatures will be elevated due to greater radiation from lack of tree canopy.

Increase in Non-native Predators

Human presence could result in an increase in garbage and other waste on the site, attracting higher numbers of predatorS such as skunks and racoons. The feral cat population may increase as result of an increase in garbage and people making feral cat feeding station. The close proximity of a large feral cat population in the Calera Creek restoration area increases the likelihood of feral cats inhabiting the project site. Cats prey on bullfrogs and likely prey on garter snakes and red-legged frogs.

Cumulative Effects

Cumulative effects include the effects of future State, Tribal, local or private actions that are reasonably certain to occur iri the action area considered in this biological opinion. Future Federal actions that are unrelated to the proposed action are not considered in this section because they require separate consultation under section 7 of the Act.

Likely future non-Federal actions in the project vicinity that will cumulatively affect garter snakes and red-legged frogs include continuing urban and suburban development, an unknown amount of illegal collecting, recreation activities such as bicycle riding, and an increase in the feral cat population in habitat of both species. Bullfrogs and warm water fishes are released into garter snake and red-legged frog habitat habitat as a result of people releasing unwanted pets and people stocking ponds for future fishing opportunities.

The Service is aware of two proposed projects within the action area that will impact garter snakes and red-legged frogs. The first is the William Bottoms/Gangi Development located south of the Recycling Plant site, west of Highway 1, and north of Rockaway Beach. The project includes a 275,000 square foot retail area, 100,000 square feet of office space on approximately 30 acres and a hotel/conference center on approximately six acres west of the Recycling Plant restoration project. Improved access to the project site will be built when Highway ·1 is widened Mr. Calvin Fong 15

(see below). The proposed project would remove 36 acres of garter snake and red-legged frog upland habitat. ·

Pacifica proposes to widen Highway 1 between Westport Drive at1d Fassler Avenue, a distance of approximately 1 mile. The proposed project will add an additional lane in each direction to provide six lanes between Reina Del Mar and Fassler Avenue. The median k-rail will be removed and replaced with landscaping. A small amount of wetland (0.1 0 acre) may be removed, but the project may be redesigned to avoid wetland impacts. Caltrans approved the project on July 23, 1999.

Runoff from the impervious surfaces created by these projects would carry petroleum-derived resides, fertilizers, pesticides and other contaminants toxic to red-legged frogs, especially to their egg and tadpole stages, impairing reproduction, survival, and development. A decrease in the red-legged frog population would impact garter snakes by reducing prey availability.

Conclusion

After reviewing the current status of the species, the environmental baseline for the action area, the effects of the proposed action and the cumulative effects, it is .the Service's biological opinion that the Pacifica Police Station, including the proposed minimization measures, is not likely to jeopardize the continued existence of garter snakes and red-legged frogs. The proposed project is riot within the proposed critical habitat designation for red-legged frogs, and critical habitat has not been proposed or designated for the ,garter snake.

INCIDENTAL TAKE STATEMENT

Section 9 of the Act and Federal regulation pursuant to section 4(d) of the Act prohibit the take of endangered and threatened species, respectively, without special exemption. Take is defined as harass, harm, pursue, hunt; shoot, wound, kill, trap, capture or collect, or to attempt to engage in any such conduct. The Service defmes harass as an intentional or negligent act or omission which creates the likelihood of injury to a listed species by annoying it to such an extent as to significantly disrupt normal behavioral patterns which include, but are not limited to, breeding, feeding, or sheltering. Harm is defined to include significant'habitat modification or degradation that results in death or injury to listed species by impairing behavioral patterns including breeding, feeding, or sheltering. Incidental take is defined as take that is incidental to, and not the purpose of, the carrying out of an otherwise lawful activity. Under the terms of section 7(b)(4) and section 7(o)(2), taking that is incidental to and not intended as part of the agency actionis not considered to be prohibited under the Act, provided such taking is in compliance with this Incidental Take Statement. Mr. Calvin Fong 16

The measures described below are non-discretionary, and must be implemented by Corps so that they become binding conditions of any grant or permit issued to the applicant, as appropriate, in order for the exemption in section 7(o)(2) to apply. The Corps has a continuing duty to regulate the activity covered by this incidental take statement. If the Corps (1) fails to require Pacifica to adhere to the terms and conditions of the incidental take statement through enforceable terms that are added to the permit or grant document, and/or (2) fails to retain oversight to ensure compliance with these terms and conditions, the protective .coverage of section 7(o )(2) may lapse.

Amount or" Extent of Take

The Service anticipates incidental take of garter snakes and red-legged frogs will be difficult to detect or quantify because of: the elusive nature of this species, its small size, and cryptic coloration make the finding of a dead specimen unlikely. Therefore, take is estimated by the number of acres in which garter snakes and red-legged frogs could be killed, harassed, trapped, captured, collected, or harmed. Upon implementation of the reasonable and prudent measures, take in the form of killing, harming, and harassing of garter snakes and red-legged frogs within the legal property boundary (approximately 4 acres ofhabitat), which includes 0.55 acre of water/wetland habitat, occurring as a result of activities associated with the project will become exempt from the prohibitions described under section 9 of the Act for direct and indirect impacts associated with the projects. This exemption applies to individuals whose duties involve implementation of the proposed project; individuals or contractors hired or contracted by Pacifica to perform duties described in this opinion. The Service has developed the following incidental take statement based on the premise that the reasonable and prudent measures will be _ implemented. Upon implementation of the following reasonable and prudent measures, incidental take associated with the Pacifica Police Station will become exempt from the prohibitions described under section 9 of the Act for direct and indirect impacts.

Effect of the Take

The Service h8.s determined that this level of anticipated take is not likely to result in jeopardy to the listed wildlife species in this opinion or result in destruction or adverse modification of critical habitat.

Reasonable and Prudent Measures

The Service believes the following reasonable and prudent measure is necessary and appropriate to minimize the impacts of take on the listed species:

1. Minimize the impact of direct effects to all life stages of garter snakes and red-legged frogs from the proposed project Mr. Calvin Fong 17

2. Minimize the impact of indirect effects to garter snakes and red-legged frogs from the proposed project.

Terms and Conditions

1. To be exempt from the prohibitions of section 9 of the Act, the Corps must comply with the following term and condition, which implement the reasonable and prudent measure 1 described above. These terms and conditions are nondiscretionary.

A. Pacifica shall implement the project, along with the proposed conservation measures for garter snakes and red-legged frogs, as described in the proposed project description. ·

B. Pacifica shall develop and record a conservation easement within six months of date of this biological opinion, unless otherwise agreed to in writing by the Service, for the in perpetuity protection of the restoration site and the remaining non-developed portion within the legal property boundary of the project site. The purpose of the conservation easement shall be for the protection of garter snakes and red-legged frogs.

c. A management plan shall be developed for the area covered by the conservation easement. A mechanism shall be set up to assure funding for the management of the conservation easement area through either Pacifica or a third party.

D. The environmental training shall include both the garter snake and red-legged frog. Construction workers shall sign the list stating that they have attended and understand the training. The Service shall be supplied with a list of all construction workers that have attended the environmental training.

E. Pacifica shall implement a Service approved maintenance program to ensure the integrity of the temporary and permanent exclosure fence and that culverts remain clear of debris.

F. The Service shall have final approval over the final planting densities.

2. To be exempt from the prohibitions of section 9 of the Act, the Corps must comply with the following term and condition, which implement the reasonable and prudent measure 2 described above. These terms and are nondiscretionary. Mr. Calvin Fong 18

B. Pacifica shall develop and institute a Service approved feral cat control program for the Pacifica Police Station site and the Recycling Plant site to prevent feral cats from becoming established on the site.

C. Pacifica shall develop and institute a Service approved bullfrog eradication program to preventbullfrogs from becoming established at' the Pacifica Police Station site.

D. No pedestrian or bicycle path shall be developed in or immediately adjacent to the Pacifica Police Station restoration area.

E. Pacifica shall institute a Service approved clean up program along Calera Creek upstream of the project site to prevent trash and other debris from entering the restored wetland area. -

F. Any straw or hay bales used on the construction site for erosion control, or any other purpose, shall be free of star thistle plants and seeds.

G. The reporting requirements stated below shall be adhered to.

The reasonable and prudent measures, with their implementing terms and conditions, are designed to minimize the impact of incidental take that might otherwise result from the proposed action. With implementation of these measures, the Service believes that all individuals and their habitat within the project's legal property boundary (approximately 4 acres) will incur some form of take through project construction activities. ·

If during the course of the action, this level of incidental take is exceeded, such incidental take represents new information requiring review of the reasonable and prudent measures. The Corps must immediately provide an explanation of the causes of the taking and review with the Service the need for possible modification of the reasonable and prudent measures.

Reporting Requirements

The Service must be notified within 24 hours of the finding of any injured or dead garter snakes or red-legged frogs, or any unanticipated damage to the species habitat associated with project -construction, minimizatiot measures, or operation. Notification must include the date, time, and precise location of the specimen/incident, and any other pertinent information. The Service contact person is Karen J. Miller, Chief, Endangered Species Division in the SFWO, at (916) 414- .6620. Any dead or injured specimens will be reposited with the Service's Division of Law Enforcement, 2800 Cottage Way, Sacramento, California 95825, telephone (916) 414-6660.

Pacifica shall notify the Service within 90 days after completion of the project. A written report shall.be submitted containing, at a minimum, the following informa.tion: ( 1) a brief summary of Mr. Calvin Fong 19 project actions; (2) the number of nonnative species removed from the project site; (3) the number and age class of red-legged frogs removed from the north pond; ( 4) any problems that occurred which might have prevented compliance with this biological opinion; and (5) methods to avoid these problems in the future. Photographs documenting the frog fencing and work progress should be included. Please reference the. Service's file number in the subject line of the report. The report should be sent to: U.S. Fish and Wildlife Service, Endangered Species Division, 2800 Cottage Way, Room W-2605, Sacramento, California 95825-1846.

CONSERVATION RECOMMENDATIONS

Section 7(a){1) of the Act directs Federal agencies to utilize their authorities to further the purposes of the Act by carrying out conservation programs for the benefit of endangered and threatened species. Conservation recommendations are discretionary agency activities to implement recovery actions, to help implement recovery plans, to develop information, or otherwise further the purposes of the Act.

In order for the Service to be kept informed of actions minimizing or avoiding adverse effects or benefitting listed species or their habitats, the Service requests notification of the implementation of any conservation recommendations. We have the following recommendations:

l. The Corps should implement conditions from the draft Recovery Plan for the California red- legged frog where their action{s) may affect the red-legged frog or its habitat. Some· conditions for implementation include best management practices to maintain natural riparian habitat, compensation for habitat lost or impacted, and reduction in or avoidance of rock or concrete in streams and other water bodies;

2. The Corps should participate in the recovery planning process for the red-legged frog;

3. The Corps should work with the Service to implement conditions and actions to benefit garter snakes where their actions may impact garter snakes.

REINITIATION-CLOSING STATEMENT

This concludes;formal consultation on the actions outlined in the request. As provided in 50 CFR §402.16, reinitiation of formal consultation is required where discretionary Federal agency involvement or control over the action has been maintained (or is authorized by law) and if: (1) the amount or extent of incidental take is exceeded; {2) new information reveals effects of the agency action that may affect listed species or critical habitat in a manner or to an extent not considered in this opinion; (3) the agency action is subsequently modified in .a manner that causes an effect to the listed species or critical habitat that was not considered in this opinion; or (4) a Mr. Calvin Fong 20 new species is listed or critical habitat designated that may be affected by the action. In instances where the amount or extent of incidental take is exceeded, any operations causing such take must cease pending reinitiation.

If you have any questions regarding. this opinion, please contact Sheila Larsen or Ken Sanchez at (916) 414-6625. '

cc: PARD (ES), Portland, OR CDFG, Yountville, CA (C. Wilcox) City of Pacific, Pacifica, CA (D. Carmany) California Department of Transportation, Oakland, CA (S. Shadle) 21

LITERATURE CITED

Bury, R.B. and J.A. Whelan. 1984. Ecology and management of the bullfrog. U.S. Fish and Wildlife Service Resource Publication 155. 23 pp.

Emlen, S.T. 1977. "Double clutching" and its possible significance in the bullfrog. Copeia1977(4):749-751.

Hitchings, S.P. and T.J.C. Beebee. 1997. Genetic substructuring as a result of barriers to gene. flow in urban Rana temporaria (common frog) populations: implications for biodiversity conservation. Heredity 79: 117-127.

Jennings, M.R. 1988. Natural history and decline of native ranids in California. Pages 61-72 In: H.F. DeLisle, P.R. Brown, B. Kaufman, and B.M. McGurty (editors). Proceedings of the conference on California herpetology. Southwestern Herpetologists Society, Special Publication (4):1-143.

Jennings, M.R. and M.P. Hayes. 1990. Status ofthe California red-legged frog (Rana aurora draytonii) in the Pescadero Marsh Natural Preserve, Report prepared for the California Department of Parks and Recreation, Sacramento, California. 30 pp. + Tables and Figures.

Kruse, K.C. and M.G. Francis. 1977. A predation deterrent in larvae of the bullfrog, Rana catesbeiana. Transactions of the American Fisheries Society

Larsen, Sheila S. 1994. Life history 'aspects of the San Francisco garter snake at the Millbrae habitat site. Unpubl. MS, Calif. State Univ., Hayward, 105pp.

L.C. Lee and Associates, 2000 Restoration Plan for the Proposed Pacifica Police Station September 13, 2000

Storer, T.I. 1933. Frogs and their commercial use. California Fish and Game 19(3):203-213.

Rathbun, G.B., K.W. Worcester, D. Holland, and J. Martin. 1991. Status of declining aquatic reptiles, amphibians, and fishes in the lower Santa Rosa Creek, Cambria, California. 21 pp.

Reh, W. and A. Seitz. 1990. The influence of land use on the genetic structure of populations of the common frog Rana temporaria. Biol Cons. 54:239-249.

Stebbins, R.C. 1985. A field guide to western reptiles and amphibians. Houghton Mifflin Company, Boston, MA. xiv + 336 pp. · 22

Twedt, B. 1993. A comparative ecology of Rana aurora Baird and Girard and Rana catesbeiana Shaw at Freshwater Lagoon, Humboldt County, California. Unpubl. M.S. Humboldt State University, Arcata. 53 pp +appendix.

USEPA. U.S. Environmental Protection Agency. 1993. Natural Wetlands and Urban . . Stormwater : Potential Impacts and Management. EPA: Washington DC. Available through EPA Wetlands Hotline. 1-800-832-7828.

U.S. Fish and Wildlife Service. 1985. Recovery plan for the San Francisco garter snake (Thampophis sirtalis tetrataenia). U.S. Fish and Wildlife Service, Portland Oregon. 77pp.

U.S. Fish and Wildlife Service. 2000a Draft Recovery Plan for the California red-legged frog (Rana aurora draytoniz). U.S. Fish and Wildlife Service, Portland, Oregon. 258 pp.

U.S. Fish and Wildlife Service. 2000b. Proposed Designation of Critical Habitat for the California Red-legged Frog (Rana aurora draytonii). U.S. Fish and Wildlife Service, Portland, Oregon.

Wright, A.H. and A.A. Wright. 1949. Handbook of frogs and toads of the United States and Canada. Comstoek Publishing Company, Inc., Ithaca, NY. xii + 640 pp.

•• MITIGATION OF 1998 EL NIÑO SEA CLIFF FAILURE, PACIFICA, CALIFORNIA BY PATRICK O. SHIRES, TED SAYRE and DAVID W. SKELLY

COTTON, SHIRES & ASSOCIATES, INC. CONSULTING ENGINEERS AND GEOLOGISTS

ARTICLE REPRINTED FROM: ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA (2001): EDITED BY HORACIO FERRIZ AND ROBERT ANDERSON, PAGES 607 - 618.

       
 

 









      

California Department Association of of Conservation Engineering Geologists Division of Mines and Geology Special Publication 12 Bulletin 210 ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA

MITIGATION OF 1998 EL NIÑO SEA CLIFF FAILURE, PACIFICA, CALIFORNIA PATRICK O. SHIRES1, TED SAYRE1, AND DAVID W. SKELLY2

ABSTRACT INTRODUCTION

Erosion of sea cliffs along the central California coastline has In February 1998, several residences on the seaward side of become a major concern for public and private improvements Esplanade Avenue were in immediate danger of collapse due constructed in harmʼs way. Stability of the local sea cliff is adversely to failure of the steep sea cliff (Figure 1). Parts of some of the affected by young, poorly consolidated sediments comprising the houses had already fallen over the bluff, others were overhanging bluff, vulnerability to wave attack under combined high wave and the bluff, and a few were intact near the edge of the bluff. high tide conditions, and elevated groundwater levels resulting House-site stability at the top of the bluff is adversely affected in seepage at the cliff face. Coastal geologic mapping and by the weak nature of the oversteepened alluvial sediments geomorphic analysis completed by the U. S. Geological Survey, comprising the lower to middle bluff, the steepness of the bluff, after extensive local shoreline damage from the 1982-83 El Niño groundwater seeping from the bluff face, and a 10-foot thick layer event, correctly identified critical erosion prone and unstable bluff of uncemented dune sand at the top of the bluff, upon which the areas. However, mitigation of identified hazards is often initiated houses were built. In addition, rapid bluff retreat represented a only shortly after catastrophic failures occur, when public interest threat to Esplanade Avenue; consequently it was essential to is sufficiently aroused to initiate Federal/State relief efforts. implement appropriate coastal protection measures if loss of this public road and associated utilities was to be prevented. Along Esplanade Avenue within the City of Pacifica, seven homes were lost or demolished during the 1998 El Niño event The northern Pacifica coastline has been undergoing because of rapid sea cliff retreat. The adjacent public road, which progressive sea cliff retreat with a long-term average erosion rate provides access to 21 local residential properties, was recognized of approximately 2 feet per year (Lajoie and Mathieson, 1998). by City, State and Federal governments as being vulnerable to It is not unusual for several years to pass with little noticeable active coastal erosion processes. The recognition of local hazards erosion, only to be followed by several feet of bluff retreat within (aided by daily television footage of homes perched at the edge of a a single day. The segment of bluff along Esplanade Avenue was retreating cliff) resulted in funding for the design and construction placed in the most unstable category by the USGS in their Coastal of a rock revetment (seawall) intended to guard against damage Stability and Critical Erosion maps as early as 1985 (Griggs and to or loss of the public roadway. This paper presents a summary Savory, 1985; Lajoie and Mathieson, 1998). When this area was of geologic, geotechnical, oceanographic, and practical factors subdivided in 1949, the length of bluff-top back yards (west of the taken into consideration during the design of the subject rock house sites) was approximately 50 feet. Figure 2 illustrates local reventment. retreat of the sea cliff between 1956 and 1998 based on aerial photographs.

Increased rates of bluff erosion in early 1998 resulted from severe winter waves, high tides, and El Niño ocean water thermal expansion effects, coupled with a diminishing natural resupply 1Cotton, Shires and Associates, Inc. of sand to the shoreline. Some bluff segments retreated over 30 330 Village Lane feet during two weeks in February 1998. Erosion at the base of Los Gatos, CA 95030 the bluffs, and landsliding of the undermined upper parts of the [email protected] bluffs were the primary processes of sea cliff retreat. In addition, increased water seepage from the bluff face softened and loosened bluff sediments, contributing to instability and retreat. 2Skelly Engineering 619 S. Vulcan Avenue Encinitas, CA 92024 Past efforts to stabilize the bluff were largely unsuccessful. In [email protected] response to rapid local bluff retreat that occurred during the 1982 DIVISION OF MINES AND GEOLOGY

Figure 1. Residences along Esplanade Avenue, Pacifica, in danger of collapse in February, 1998.

El Niño event, a homeowners group in cooperation with the City Conspicuous within the City of Pacifica are several broad, of Pacifica funded construction of a rock revetment. The lack of relatively flat-floored valleys that open to the ocean, suggesting adequate maintenance, coupled with adverse design aspects (rock periods of channel incision into bedrock followed by fluvial size was relatively small and apparently not keyed into bedrock deposition. During the last major ice age, sea level was more materials), resulted in a short life-span for this structure. Although than 100 feet lower than it is at present. Upon final melting of the relatively intact sections of this revetment were still visible in large continental glaciers (initiated approximately 15,000 years 1996, by March 1998 the earlier revetment had been reduced to ago), sea level rose, changing the base levels of coastal drainage an irregular scattering of boulders across the narrow sandy beach channels. Consequent reductions in stream gradients resulted in (Figure 3). lower flow-velocities and burial of eroded channels with alluvial deposits. Near Esplanade Avenue, subsequent tectonic uplift and SITE GEOLOGY coastal erosion has notched sea cliffs into these alluvial deposits. This recent geologic history has resulted in the deposition and The site is located along the California coastline (Figure 4), exposure of the relatively young, poorly consolidated sediments approximately 1.3 miles south of Mussel Rock where the San that form the local bluffs. Periods of rapid bluff retreat can be seen Andreas fault enters the Pacific Ocean. Steep bluffs fronted by as one consequence of this dynamic geologic setting. narrow, sandy beaches characterize this section of the coastline. Bluff height increases from approximately 70 feet along Esplanade In the area under study, “greenstone” bedrock of the Franciscan Avenue to greater than 300 feet north of Mussel Rock. A terrace Complex lies below the base of the bluff. This rock is a relatively surface to the northeast of the bluff is clearly warped as a result of firm to hard altered submarine basaltic assemblage composed of geologically active uplift along the tectonic plate boundary. pillow lavas, flows and breccias. It is overlain partially by beach ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA sand in the tidal zone, and by an approximately 50-foot thick section of poorly lithified Quaternary alluvial  fan deposits (coarse basal breccia, intervals of poorly indurated silts, and fine to medium grained sands and gravels) exposed in the lower portion of the bluff. The  alluvial deposits are overlain by a clayey, dark brown soil horizon, approximately 5 feet thick. Capping the   soil horizon, and extending to the current ground surface,  is a 10-foot thick layer of dune sand. Figure 5 illustrates the stratigraphy of the sea cliff and position of the rock revetment.

The uncemented dune sand is very weak when  unconfined, especially when it loses moisture-related interstitial tensile forces (Figure 6). House loads provide  some confinement pressure and help contain this sand when it is moist. When it becomes dry, it seeks its  natural angle of repose at approximately 30 degrees (or approximately 1.7 horizontal to 1 vertical). In addition  to the weak dune sand, the underlying soil and alluvial deposits, although stronger than the dune sand, are prone to sloughing, and larger-scale slumping.  

 REVETMENT DESIGN

The following section summarizes the methodology  utilized for the design of a quarry stone revetment (seawall) intended to reduce the potential for future, rapid sea cliff erosion and provide protection for Esplanade Avenue and associated utilities.   Oceanographic design considerations

The recommended coastal structure design criteria reflect consideration of nearshore bathymetry, water level, wave height, maximum scour elevation, beach slope, and bedrock material properties. The design methods used in Figure 2. Top of bluff retreat from 1956 to Spring 1998 (modified from our analysis were taken from Chapter 7 of the U.S. Army Lajoie and Mathieson, 1998) Corps of Engineers Shore Protection Manual (U.S. Army, 1984). With this method, design criteria are developed wave group effects (1.0 to 2.5 feet), and El Niño thermal water for a set of recurrence interval oceanographic conditions. Both 50- expansion effects (0.5 to 1.0 feet). The 50-year recurrence interval year and 100-year recurrence interval oceanographic conditions maximum high tide elevation is +5.4 feet MSL (Mean Sea Level) were evaluated in our analysis. which, when combined with the effects of super-elevation, yields a 50-year recurrence interval water level of +7.0 feet MSL. The The offshore bathymetry is characterized by ridges and valleys 100-year recurrence interval maximum tide elevation is +5.9 feet, aligned perpendicular to the shoreline. An approximate nearshore which could result in a maximum water level of +7.5 feet MSL. slope of 0.2% was assumed. The beach slope varies across the proposed revetment site from as steep as 30% to less than 18%. The “maximum scour depth” is determined by the rate at which the bedrock, that the revetment structure is founded upon, wears The “design water level” is the maximum possible still- down. The lower formational material at this site is greenstone water elevation. During storm conditions, the sea surface rises bedrock of the Franciscan Complex, a firm, but erodible material. along the shoreline (super-elevation) and allows waves to break The down-wearing rate was estimated to be approximately 1 just before, or at, the revetment structure. In this study, super- inch per year for the purposes of project design (the actual rate elevation of the sea surface was accounted for by wave set-up (1.0 of abrasion would be expected to diminish at depths significantly to 2.5 feet), wind set-up and inverse barometer (0.5 to 1.5 feet), below MSL). The elevation of the existing grade at the toe of the DIVISION OF MINES AND GEOLOGY

Figure 3. Remnants of previous rock revetment scattered across the beach after the 1998 El Niño event. lowest segment of the revetment is approximately 3 feet below Wave run-up mean sea level. Accounting for bedrock down-wearing, and using maximum still-water levels, the design water depth (i.e., elevation As waves encounter a revetment, they break and the water difference between the revetment toe and maximum still-water rushes up the face of the structure. Often, wave run-up and level) at the revetment for the 50-year recurrence interval overtopping strongly influence the design and cost of coastal conditions is approximately 12 feet. The design water depth for projects (Weggel, 1976). “Wave run-up” is defined as the vertical the 100-year recurrence interval is approximately 15 feet. These height above the still water level to which a wave will rise on a static submergence depths are utilized in the following section for structure of infinite height. “Overtopping” is the flow rate of the calculation of wave run-up. water over the top of a revetment as a result of wave run-up. The run-up analysis is performed to determine the design height In general, high waves in combination with high water levels of the revetment so that no overtopping can occur. Overtopping locally result in erosion of beaches and wave attack at the base of of the structure would exacerbate erosion of the alluvial deposits the coastal bluffs (Figure 7). At this site, offshore wave heights comprising the middle of the bluff. exceeding 20 feet are not uncommon during winter storms. However, the design wave condition for a shoreline structure is Wave run-up and overtopping for the revetment was calculated generally not the largest wave, because the largest waves break using the U.S. Army Corps of Engineers Automated Coastal offshore in water depths approximately equal to the wave’s height. Engineering System, (ACES). ACES is an interactive, computer- The largest “design wave force” will occur when a wave breaks based design and analysis system commonly used in the field directly on the shoreline structure. The largest wave that can of coastal engineering. The methods to calculate run-up and break on the revetment is determined by the depth of water at overtopping implemented within this ACES application are the toe of the structure. Using the water depths dened earlier, discussed in greater detail in Chapter 7 of the Shore Protection the resulting design wave heights are 10.0 feet for the 50-year Manual (U.S. Army, 1984). The run-up estimates calculated recurrence interval and 12.0 feet for the 100-year recurrence herein are corrected for the effect of onshore winds (i.e., wind interval. Incoming wave periods vary from 9 to 20 seconds. A direction from sea to land). design period of 20 seconds was selected because this period wave would produce the highest run-up. ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA

.

 

"AY"RIDGE -),%3

'OLDEN'ATE /AKLAND "RIDGE 3AN &RANCISCO

3)4% 3AN &RANCISCO "AY 0ACIFICA !NDREAS3AN

3AN-ATEO 0 "RIDGE ILA RC I TO S

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& A &AULT U 3AN LT *OSE

Figure 4. Location of the Esplanade Avenue site within the City of Pacifica.

The empirical expression for the monochromatic-wave hs = height of structure (ft), and overtopping rate is: ds = water depth at structure (ft). 3 1/2 -0.1085/∝ Q = Cw (g Q0* H0 ) [(R+F)/(R-F)] , where: The correction for onshore winds is: Q = overtopping rate per unit length of structure (ft3/sec.ft)

Cw = 1 + Wf (F/R + 0.1) sin(θ), where: Cw = wind correction factor, 2 Wf = U /1800 g = gravitational acceleration (ft/sec2), U = onshore wind speed (mph)

Q0*, ∝ = empirical coefcients (see SPM Figure 7-27), F = hs - ds = freeboard (ft)

H0 = unrefracted deepwater wave height (ft), R = run-up (ft) R = run-up (ft), θ = angle of the ocean-facing revetment slope, measured from F = hs - ds = freeboard (ft), horizontal in degrees. DIVISION OF MINES AND GEOLOGY

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Figure&IGURE 5.3TRATIGRAPHYOFSEACLIFFANDROCKREVETMENTPOSITIONNEART Stratigraphy of the sea cliff and rock revetment HESOUTHERNTERMINOUSOF%SPLANADE!VENUEposition near the southern terminus of Esplanade Avenue.

The severity of storm impacts to the local coast are partially The primary factor in determining the design stone weight is the dependent on the direction of wave approach and the local incident wave energy, which is proportional to the wave height. shoreline orientation (Fulton-Bennet and Griggs, 1987). The The output of the ACES analysis includes the stone weight and ACES analysis was performed on two sets of local oceanographic revetment crest width. The weight of the stone required to conditions that represent typical 50- and 100-year storms. The withstand the design wave conditions is given by the following onshore wind speed was chosen to be 60 knots (69 mph) for each formula: case. 3 3 W = Wr H /[(KD(Sr-1) cot(θ)], where: The output from the ACES analysis indicates that the maximum wave run-up for the 50-year recurrence interval oceanographic W = Weight of the individual armor stone in the conditions is approximately +17 feet MSL, and for the 100-year primary cover unit (lbs), recurrence conditions, approximately +19 feet MSL. Based upon this analysis, the height of the revetment for a “no overtopping” Wr = Unit weight of the armor stone (pcf), condition should be a minimum of +20 feet MSL. A top of revetment elevation of +26 feet MSL was selected to buttress H = Design wave height (ft), a lower sand lens on the bluff face, to allow for future settling of the revetment and to increase the factor-of-safety in project Sr = Specic gravity of the armor stone relative to design. Site observations during storm conditions and engineering water (Sr = Wr/Ww), judgement also influenced the selection of final revetment height. Ww = The unit weight of water (pcf), Revetment geometry and stone weight considerations θ = Angle of the structure slope measured from horizontal in degrees, and For initial design purposes, an armor stone unit weight of 165 K = Stability coefcient which depends on the pcf and a 50% slope for the face of the structure were selected. D shape of the armor stone. ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA

Figure 6. Loose dune sand exposed in the upper cliff face, immediately beneath the residence.

The calculated individual armor stone weight for the 50- breaking during handling. The armor stone consisted of select year oceanographic conditions is approximately 5 tons. The quarry rock free of open fissures and apparent planes of weakness. crest width is approximately 12 feet, with approximately 80 Ideally, armor stone should be rough and angular in shape, with armor stones per 1,000 square-feet for 50-year recurrence the shortest principal dimension not less than one-third the longest conditions. The individual armor stone weight for the 100-year dimension to improve interlocking qualities. wave conditions is approximately 10 tons, with a crest width of approximately 14 feet. This results in approximately 50 armor The qualitative evaluation of rock durability relates to the stones per 1,000 square feet. Ultimately, an armor stone size of geological origin of the rock, as well as specific tests to evaluate 8 to 10 tons was selected for project design considering several rock properties important to longevity as a revetment component. years of performance observarions by the Pacifica Public Works Rock evaluation should include consideration of the following: Department, available funding, and the restricted availability of 1. Examination of the petrographic make-up of the rock rock in the 10-ton range. should be completed.

Quarry stone selection and placement 2. Evaluation should be made of the performance of the candidate rock type in other marine structures. Two weight ranges of stone are generally selected for revetment construction: armor stone and core stone. The armor stone 3.Testing to address the Standard Practice for Evaluation weight ranged from 8 to 10 tons, whereas the core stone weight of Rock to be Used for Erosion Control (ASTM D ranged from 100 pounds to 5 tons. The smaller size fraction of 4992-94)should be conducted. Testing may include: the core stone was placed deepest within the revetment. All the stone material was examined to verify that the rock was free a. C 88 - Test method for soundness of aggregate of undesirable qualities that might contribute to crumbling or by use of sodium sulfate or magnesium sulfate; DIVISION OF MINES AND GEOLOGY

CONSTRUCTION CHALLENGES

Suitable, large armor stones in the 8- to 10-ton size range were difficult to obtain because significant demands for large rock had been placed on local quarries during El Niño conditions. Rock samples from four quarries, with haul distances of approximately 40 to 100 miles to the site, were delivered for detailed examination. Samples included limestone, graywacke sandstone, welded volcanic tuff and a metaconglomerate. Submitted samples, other than the limestone, generally had favorable density and durability properties. Due to the scarcity of large rock, favorable rock types available from three quarries were utilized for project construction.

Trucks delivering armor stones to the site would typically accommodate only two large stones per load, with possibly room for a few smaller core stones. Because the keyway for the revetment was to extend into Franciscan bedrock located below mean sea level, stone placement was possible only during periods of low tide (Figure 9). Sufficient stone for the construction of a 100-foot segment of the revetment was delivered to a staging area high on the beach, and placement of rock into the keyway (excavated the previous day) occurred during low tide.

Rock was placed in conformance with the following guidelines, with the guiding principle that good craftmanship during stone placement is essential to structural integrity: 1) rock-to-rock contact was maximized (at least three points of contact per stone) and the voids were minimized; 2) stones that were flat in one dimension were preferred and round stones were avoided; 3) Figure 7. Offshore wave height may exeed 20 feet and stones that had one particularly long dimension were placed with wave surge from shore break attacks the base of coastal the longer dimension perpendicular to the shoreline to prevent bluffs during high tides. rolling down slope; and 4) “chink” armor stones (smaller than 3 feet in their longest dimension) were not usedvthe larger armor stones.

b. C 127 - Test method for specific gravity and MAINTENANCE absorption of coarse aggregate; Any large engineered structure placed along the base of a sea c. C 294 - Descriptive nomenclature of constituents of cliff will interact with dynamic shoreline erosional processes. natural mineral aggregate; Consequently, such structures require periodic inspection and maintenance. Inspections should be performed by an engineer d. C 295 - Practice for petrographic examination of with experience in coastal structures. In addition, coastal aggregate for concrete; structures should be inspected by the property owners after any major storm for damage caused by wave attack. When damage e. C 535 - Test method for resistance to degradation is observed, an engineer should be consulted to determine the of large-size coarse aggregate by abrasion and nature and extent of necessary maintenance. Maintenance on a impact in the Los Angeles machine; and quarry stone revetment would include re-shaping the revetment to the design profile through addition or repositioning of stones. f. D 5313 - Test method for evaluation of durability Maintenance of the revetment should be undertaken in a manner of rock for erosion control under wetting and drying that will improve the quality of the profile, as well as the contact conditions. and orientation of the individual stones. The rehabilitation of ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA

Figure 8. Filter fabric is being placed in the keyway and along the base of the revetment prior to stone placement. a revetment should be supervised by a coastal engineer. The hazard to adjacent residential development. One limitation for the City of Pacifica has reportedly taken steps toward establishing a placement of a revetment at the base of the bluff is that it will not maintenance assessment district to ensure that funding is available significantly improve stability of the slope above the revetment for periodic upkeep of the revetment. crest (elevation of 26 feet MSL). Although dewatering measures may improve slope stability by reducing adverse groundwater SUMMARY/COMMENTARY seepage from the face of the bluff, the viability of the bluff lots for redevelopment will depend on the outcome of detailed Key aspects of revetment design included selection of adequate geotechnical studies. In addition, revetments have design-life armor stones, keying of imported stone below beach and alluvial limitations and maintenance requirements that must be considered deposits well into firm bedrock, and selection of an appropriate during redevelopment evaluations. revetment face-slope and height. Design parameters were based on oceanographic analysis including consideration of maximum Engineering efforts to arrest coastal erosion processes should possible still-water levels, wave run-up, the design wave force, be viewed as temporary solutions that are often not free of and anticipated scour depth. Final quarry stone selection included collateral impacts (Griggs, Pepper and Jordan, 1992). In the consideration of constituent mineralogy, rock density and case of engineered revetments or seawalls, these structures are anticipated durability in a dynamic marine environment. typically constructed at locations that already have inadequate protective beach or dune buffer zones. The sand-deficient Even though the design intent of the revetment is to help protect beaches may become narrower and steeper with time after the the nearby public roadway from coastal erosion, there may be protective structure is installed. These changes may result from pressures to redevelop what remains of the top lots on the bluff. increased rebound energy of waves reflected off relatively hard, Landsliding along the precipitous bluffs is a significant potential fixed engineered structures, and the reduction of cliff detritus DIVISION OF MINES AND GEOLOGY

Figure 9. Keyway excavation below mean sea level required strategic construction timing with respect to tidal conditions. descending to the beach. Consequent alteration to the beach and AUTHOR PROFILE near-shore profiles can ultimately undermine foundation support of the protective structure. It is also possible that erosion of adjacent Cotton, Shires & Associates, Inc. is a geotechnical consulting vulnerable coastal bluffs may result in gradual outflanking of the firm established in 1974 providing services from offices in Los protective structure. With the best revetment or seawall designs, Gatos and Carlsbad, California. We offer expertise to engineers, protective success over the time period of a human life span can designers and local governments with regard to development, occasionally be achieved. From a long-term geologic perspective, hazard analysis and mitigation, commercial and municipal however, protective revetments placed within wave impact zones construction and failure analysis. We also provide expert witness will eventually face inevitable consequences. Utilization of testimony for litigation and arbitration related to geotechnical protective design alternatives in dynamic coastal zones should engineering and engineering geology. Mr. Ted Sayre is a Certified follow full consideration of a cost-and-benefit analysis, impacts to Engineering Geologist with 17 years of local experience. Mr. beaches and adjacent properties, and alternative hazard avoidance/ Patrick O. Shires is the firmʼs Principal Geotechnical Engineer relocation options. with 28 years of experience addressing complex geotechnical problems in the western United States. Mr. David W. Skelly is a ACKNOWLEDGMENTS Professional Engineer with expertise in Coastal Engineering who works with Cotton, Shires and Associates on special projects. The authors thank Gary Griggs of U. C. Santa Cruz and Kenneth Lajoie of the U. S. Geological Survey for their tireless efforts to characterize California coastal hazards and to educate the public about consequent risks of living in this dynamic environment. We also express gratitude to the team of Section Editors who greatly enhanced the quality of the final manuscript. ENGINEERING GEOLOGY PRACTICE IN NORTHERN CALIFORNIA

REFERENCES Markel, D. G., and Davidson, D. D., 1979, Placed stone stability tests, Tillamook, Oregon; hydraulic model investigation: U.S. Army Corps of Engineers, Waterways Exp. Station, Vicksburg, Aherns, J. P., 1997, Prediction of irregular wave overtopping: U.S. MS. Army Corps of Engineers, Waterways Exp. Station, Vicksburg, MS. National Research Council, 1990, Managing coastal erosion: National Academy Press, Washington, D.C., 182p. Aherns, J. P., and Mc Cartney, B. L., 1975, Wave period effects on the stability of rip rap: Proceedings of Civil Engineering in the Oceans/III, American Society Of Civil Engineering., p. 1019- National Research Council, 1987, Responding to changes in 1034. sea level-Engineering implications: National Academy Press, Washington, D.C., 148 p.

Douglass, S. L., and Smith, O. P., 1986, Cost-effective optimization of rubble-mound breakwater cross sections: U.S. Army Corps of Norris, R., 1990, Seacliff erosion: A major dilemma: California Engineers, Waterways Exp. Station, Vicksburg, MS, p. 45-53. Geology, v. 43, no. 8, p. 171-177.

Ewing, L., and Sherman, D. (Editors), 1998, California’s coastal U.S. Army,1996, Shoreline protection and beach erosion control natural hazards: Sea Grant Program, Univ. of Southern Calif., study: Corps of Engineers, Institute for Water Resources, 162 p. Alexandria, VA, 226 p.

Fulton-Bennet, K., and Griggs, G. B., 1987, Coastal protection U.S. Army, 1984, Shore protection manual: Corps of Engineers, structures and their effectiveness: Calif. Dept. of Boating and Coastal Engineering Research Center, Waterways Exp. Station, Waterways, 48 p. Vicksburg, MS, 2 Volumes.

Griggs, G. B., Pepper, J. E., and Jordan, M. E., 1992, California’s Weggel, J. R., 1972, Maximum breaker height: Journal of coastal hazards: A critical assessment of existing land-use policies Waterways, Harbors and Coastal Engineering Division, American and practices: California Policy Seminar, University Of California, Society of Civil Engineers, v. 98, no. WW4, p. 529-548. 224 p. Weggel, J. R., 1976, Wave overtopping equation: Proceedings of th Griggs, G. B., and Savoy, L. E. (Editors), 1985, Living with the the 15 Coastal Engineering Conference, American Society of California coast: Duke Univ. Press, Durham, N.C., 393 p. Civil Engineers, Honolulu, HI, p. 2737-2755.

Lajoie, K. R., and Mathieson, S. A., 1998, 1982-83 El Niño coastal erosion, San Mateo County, California: U. S. Geological Survey Open File Report. 98-41, 61 p.

Lajoie, K. R., and Mathieson, S. A., 1985, Living with the California coast: Duke Univ. Press, Durham, N.C., p. 140-177.

Norris, R., 1990, Seacliff erosion: A major dilemma: California Geology, v. 43, no. 8, p. 171-177.