MBSST Mitigation Final Design Hydraulics Memo .pdf

Technical Memorandum

Jacobs Engineering Group Inc.

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Final Hydrologic and Hydraulic Technical Memorandum

Date: April 11, 2025 999 W. Main St Suite 1200 Boise, ID 83702 United States

T +1.208.383.6208 www.jacobs.com

Project name: Monterey Bay Sanctuary Scenic Trail (MBSST) Mitigation

Client: United States Department of Transportation Federal Highway Administration (FHWA) Central Federal Lands Highway Division (CFLHD)

Prepared by: I. Matagi PE

Document no: R2

1. Introduction

This technical memorandum summarizes the preliminary hydrologic and hydraulic analysis completed on the proposed wetland mitigation site. Surface water drainage features and hydrologic analysis are proposed and completed to meet the County of Santa Cruz Design Criteria because the project site is located within that jurisdiction. No surface water drainage features are proposed at this site related to offsite rainfall runoff.

A preliminary hydrologic and hydraulic analysis was completed in a preemptive effort to quantify stormwater runoff surrounding the project site. These values were utilized to aide in the identification of a suitable location for wetland mitigation.

2. Design Criteria and Standards

The County of Santa Cruz “Design Criteria” were consulted and implemented in completing the hydrologic analysis of existing and proposed drainage patterns.

A hydrologic water balance analysis was conducted to identify potential surface water runoff available for the design and feasibility of wetland mitigation facilities.

A specific storm event is not proposed to be utilized in the hydrologic analysis of this mitigation due to the nature of water balance design.

3. Existing Drainage Conditions

The project site is in Santa Cruz County along Pacific Coast Highway. The project vicinity consists of coastal bluffs and rural areas within unincorporated Santa Cruz County. The mitigation site is near Panther Beach along the California State Highway 1, locally knows as the Cabrillo Highway, approximately 7 miles north of the City of Santa Cruz, CA, just southeast of the Yellowbank Creek outlet. A project location map is available in the Project Technical Memorandum (30% Design) document.

Regional drainage near the project site is from northeast to southwest in coastal tributaries which discharge directly to the ocean. Based on aerial imagery and topographic data, surface water runoff discharges via sheet flow to earthen ditches that parallel both Cabrillo Highway as well as a parallel railroad embankment. These ditches discharge north and south of the mitigation site to local depressions

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4. Hydrology

To facilitate the completion of a surface water runoff water balance analysis, the United State Department of Agricultures (USDA) Soil Conservation Service (SCS) hydrologic methodology was utilized.

Methodology and parameter estimation were completed following procedures outlined in the USDA’s Technical Release 55 Manual (TR-55). This methodology utilizes the runoff curve number estimation for determination of runoff peak flow rates and volumes.

Drainage basins were delineated using existing available topographic surfaces from prior design efforts related to the CA FLAP SCR T5(1) Monterey Bay Sanctuary Scenic Trail project. These drainage basins were identified to represent the existing conditions. Drainage basin area data was measured utilizing computer aided drafting files provided from the available survey data.

Monthly average precipitation values were obtained from the Western Regional Climate Center from two adjacent precipitation gauges shared with the National Oceanic and Atmospheric Association. These precipitation gauges include the Davenport (042290) and the Santa Cruz (047916) gauges. For the Santa Cruz gauge, the entire period of record (1893 to 2022) was available for monthly total precipitation only.

For the Davenport gauge, the entire period of record (1960 to 1977) was available for the maximum monthly precipitation only. The average of these two data sets were conservatively assumed to represent a typical water year for the study area.

Land use and the identification of the land cover is needed in order to calculate surface runoff curve numbers that will help in the calculation of runoff volumes. Land use and land cover for the delineated basins are primarily a mixture of brush and grass that was identified within historical aerial imagery and confirmed through field visits.

Hydrologic soil types within each delineated drainage basin were identified to calculate a surface runoff curve numbers for calculation of runoff volumes. Hydrologic soil groups and distribution within the drainage areas have been mapped and classified by the USDA and the NRCS. For hydrologic purposes, these soils are usually classified as A, B, C, or D soils. These classifications relate to the ability of the surface horizons to infiltrate stormwater at various rates. These data were obtained in unique report format from the NRCS Soil Survey Geographic database at http://websoilsurvey.nrcs.usda.gov. The study area includes a mixture of mostly ‘A’ with some ‘B’ hydrologic soil types. These were also verified within recent field visits.

Individual runoff curve numbers used to calculate runoff volume were determined based on the combination of land cover and hydrologic soil types. Runoff curve numbers presented in Table 2-2c of the TR-55 manual were consulted based on average runoff conditions for agricultural lands. A runoff curve number of 48 was estimated to coincide with a land cover of brush, and a weed-grass mixture with relatively good vegetative cover.

Initial abstraction and potential maximum runoff retention values were estimated utilizing Equation 2-2 and 2-4 from the TR-55 manual, respectively. Utilizing average monthly precipitation, runoff curve numbers and runoff equations included in the TR-55 manual, runoff volumes for each delineated drainage basin were determined. Total runoff volume in terms of inches was calculated via Equation 2-3 within the TR-55 manual. Runoff volume in terms of acre-feet were calculated utilizing Equation 6-1 within the TR- 55 manual.

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Table 1 below illustrates the resulting calculations on a monthly basis. Resulting calculations show typical rainfall estimates and calculated runoff during the winter months and negligible rainfall and runoff during the summer months.

Table 1 Hydrologic Summary

Month Precipitation (in) Runoff Volume

(in) Drainage Area “E1” Drainage Area “E2” acft cuft acft cuft

January 5.40 0.74 0.19 8205 0.84 36776

February 4.66 0.46 0.12 5146 0.53 23063

March 3.97 0.26 0.07 2849 0.29 12769

April 1.95 0.00 0.00 0 0.00 0

May 0.56 0.00 0.00 0 0.00 0

June 0.27 0.00 0.00 0 0.00 0

July 0.11 0.00 0.00 0 0.00 0

August 0.13 0.00 0.00 0 0.00 0

September 0.35 0.00 0.00 0 0.00 0

October 1.48 0.00 0.00 0 0.00 0

November 3.90 0.24 0.06 2633 0.27 11799

December 4.79 0.51 0.13 5662 0.58 25376 in : inch acft : acre-feet cuft : cubic-feet

5. Hydraulics

No proposed hydraulic facilities are included in this phase of the proposed project. Hydraulic calculations will be completed, when necessary.

6. Recommendations and Conclusions

Hydrologic analysis has resulted in calculated potential monthly runoff volumes for the delineated drainage basins within the study area. These volumes appear to match seasonal estimates with the majority of the volume available during the winter months and negligible volumes in the summer months.

No proposed hydraulic facilities are included in this phase of the proposed project.

Hydrologic parameter estimation and backup data are included in the following Attachments.

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7. References

County of Santa Cruz. 2019. County of Santa Cruz Design Criteria, Containing Standards for the Construction of Streets, Storm Drains, Sanitary Sewers, Water Systems, Driveways, Within the Incorporated Portion of Santa Cruz County. June 2019 Edition.

Jacobs. 2024. Project Technical Memorandum (30% Design). Monterey Bay Sanctuary Scenic Trail. CA FLAP SCR T5(1A) Preliminary/Final Mitigation Design. Federal Highway Administration Central Federal Lands Highway Division. December.

United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). 2024.

Web Soil Survey. https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm. Accessed 11/04/2024.

United States Department of Agriculture (USDA) Natural Resources Conservation Service. 1986. Urban Hydrology for Small Watersheds TR-55. Conservation Engineering Division. June

STATE PROJECT

A

M N C

A s c r t5 R o a d w a y C

A D

D S h e e ts

W

M A I N S

C R

T .d g n

CENTRAL FEDERAL LANDS HIGHWAY DIVISION

FEDERAL HIGHWAY ADMINISTRATION

U.S. DEPARTMENT OF TRANSPORTATION

U s e r J e ff r e y .F e ll in g

NUMBER

SHEET

MBSST

CA

CA FLAP SCR T5(1) & (2)

.9

VPI 3+00

EL 74.68

-9 .6

-1.343%

60' VC

VPI 4+25

EL 73.00

+0.497%

76' VC 7

.6

5 8

90 90

0+

5+

.9

V P I

E L

.9

-8 .5

40' VC

VPI 3+75

EL 70.51

-9 .9

+2.26 2%

110' VC

VPI 4+55

EL 72.32

7.

1%

50' VC

.3

200'100'0

Scale in Feet

NOTE:

Sheet 1 of 1

WETLAND MITIGATION SITE

0'-8"

1'-0"

1' -0

Native Material 1+00 2+00 3+00 4+00 5+00 6+00 7+00

PROFILE: NORTH - SOUTH

PROFILE: EAST - WEST

0+00

0+00 1+00 2+00 3+00 4+00 5+00 6+00 7+00 8+00

8+00

4.

3.

2.

1.

Limits of construction

Fill in existing ditch

MITIGATION SITE

fill in outlet

Construt berm to

NO SCALE

Existing Ground

Existing Ground

Proposed Grade

Proposed Grade

SEDGE PLUG DETAIL

PLANTING DETAIL

Sedge Plug (typ.)

Boulder (typ.)

Willow Planting (typ.)

Spacing TBD Spacing TBD

Finished Ground

Native Material

Topsoil according to Section 626. Planting and boulder quantities TBD.

Place boulders according to Section 251. Plant willows and sedge plugs ratio may be adjusted by the CO to assure adequate drainage and stability.

The gradient and Width of wetland and the excavation and embankment slope data. Verify limits of disturbance, and restoration prior to beginning work.

restoration, proposed finish grades, slopes are not based on precise survey

Perform grading and construct berms according to Section 204. Limits of to Section 201. Conserve and stockpile topsoil according to Section 624.

Establish Erosion Control according to Section 157. Clear the area according

15' to 20' apart.

see SCR's for details. Place boulder

Alternate sedge plugs with boulders, Mitigation Site #1

AREA ID: "E2"

AREA: 13.67

AREA ID: "E1"

AREA: 3.05

OUTFALL B

OUTFALL A

DELINEATED DRAINAGE BASIN

SURFACE FLOW DIRECTION

LEGEND

SANTA CRUZ, CA

Total of Precipitation (Inches)

-47916

File last updated on November 4, 2024 a = 1 day missing, b = 2 days missing, c = 3 days, ..etc.., z = 26 or more days missing, A = Accumulations present

Long-term means based on columns; thus, the monthly row may not sum (or average) to the long-term annual value.

MAXIMUM ALLOWABLE NUMBER OF MISSING DAYS : 5

Individual Months not used for annual or monthly statistics if more than 5 days are missing.

Individual Years not used for annual statistics if any month in that year has more than 5 days missing.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1893 5.30 4.25 9.95 1.65 0.36 0.00 0.00 ----- 0.25 0.75 4.40 3.50 30.41

1894 7.02 8.60 2.09 0.66 2.36 0.72 ----- ----- 2.77 ----- ----- 13.44 22.13

1895 9.11 4.07 3.08 2.02 1.15 ----- ----- ----- 0.18 0.49 1.89 2.15 16.99

1896 8.52 0.25 3.69 3.07 1.66 0.00 0.05 0.73 0.35 1.88 6.79 4.87 31.86

1897 3.72 4.96 4.86 0.22 0.24 ----- ----- ----- 0.17 1.49 0.55 ----- 15.66

1898 2.17 2.67 1.39 0.52 1.35 0.06 ----- 0.00 2.21 0.40 0.86 2.24 13.87

1899 7.27 0.45 9.31 1.21 0.95 0.14 0.00 0.05 0.00 7.05 3.70 4.42 34.55

1900 5.49 0.99 3.58 2.21 0.94 0.00 0.00 0.00 ----- 2.11 7.87 2.48 25.67

1901 4.30 5.91 0.94 2.01 0.52 0.00 0.00 0.00 0.64 0.88 3.28 1.80 20.28

1902 2.31 14.74 3.23 1.83 0.64 0.00 0.00 0.00 0.00 2.10 2.74 2.23 29.82

1903 6.25 2.07 11.06 0.25 0.00 0.00 ----- 0.00 0.00 ----- 8.59 ----- 28.22

1904 1.85 5.55 8.35 3.14 0.02 0.00 0.00 ----- 4.70 3.63 2.37 2.11 26.17

1905 6.95 4.65 5.15 2.50 3.47 ----- 0.02 0.00 0.00 0.00 2.50 2.09 24.83

1906 4.93 7.70 8.69 1.50 3.85 0.98 0.00 ----- 0.30 0.00 2.30 8.03 26.4

1907 8.22 4.10 10.85 0.10 0.35 1.10 0.00 0.00 0.40 3.00 0.00 5.50 33.62

1908 6.55 4.85 2.35 ----- 0.42 0.00 ----- 0.00 0.25 1.41 2.04 3.95 21.82

1909 19.90 9.35 4.60 0.03 0.00 0.10 0.00 0.00 1.47 1.80 1.77 11.39 45.81

1910 6.50 ----- 6.50 0.50 0.00 0.05 0.00 0.00 0.04 1.21 0.70 1.80 10.8

1911 16.03 5.63 5.71 1.63 0.50 0.25 0.00 ----- ----- 0.85 1.10 3.41 31.7

1912 5.06 0.61 4.65 2.17 1.86 0.45 0.00 0.00 0.73 0.77 1.82 1.13 14.19

1913 5.57 0.37 2.05 0.58 0.82 0.25 0.35 ----- 0.00 0.00 5.78 9.23 25

1914 9.79 5.74 1.03 2.27 0.25 0.65 0.10 0.02 0.05 1.57 2.62 8.51 14.8

1915 10.05 9.90 2.17 1.63 5.55 ----- ----- ----- 0.02 0.02 0.55 4.45 22.81

1916 15.49 5.77 2.85 ----- 0.25 0.00 ----- 0.00 0.65 0.70 ----- 6.75 16.97

1917 2.72 4.60 1.20 0.75 0.20 ----- ----- ----- ----- ----- 1.25 1.55 7.67

1918 1.25 4.33 3.11 0.44 ----- ----- ----- 0.05 6.60 0.46 4.20 2.40 19.73

1919 1.70 9.12 3.07 0.04 0.07 ----- ----- ----- 0.60 ----- ----- 6.18 14.6

1920 2.90 2.00 5.57 1.95 ----- 0.30 ----- ----- ----- 2.88 4.92 7.47 23.07

1921 5.82 3.30 1.65 0.80 1.35 ----- ----- ----- ----- 0.50 1.60 10.10 25.12

1922 3.95 6.15 4.15 ----- ----- ----- ----- 0.00 ----- 2.92 3.25 8.70 20.05

1923 4.45 ----- ----- 6.60 ----- 0.60 ----- ----- 0.65 ----- 0.50 2.35 15.15

1924 3.15 ----- 2.55 0.30 0.00 ----- ----- ----- 0.00 2.45 ----- 3.85 8.45

1925 ----- 7.80 2.75 2.55 5.00 ----- 0.00 ----- 0.50 0.50 2.20 2.10 20.65

1926 6.35 8.25 0.25 5.60 0.30 0.00 0.00 0.00 0.00 1.20 6.25 1.30 21.25

1927 4.75 10.45 2.75 2.10 0.00 0.35 0.00 0.00 0.10 ----- 3.20 5.30 29

1928 ----- 3.30 5.30 0.30 0.25 ----- 0.00 0.00 0.00 0.00 3.80 5.75 12.95

-47916

File last updated on November 4, 2024 a = 1 day missing, b = 2 days missing, c = 3 days, ..etc.., z = 26 or more days missing, A = Accumulations present

Long-term means based on columns; thus, the monthly row may not sum (or average) to the long-term annual value.

MAXIMUM ALLOWABLE NUMBER OF MISSING DAYS : 5

Individual Months not used for annual or monthly statistics if more than 5 days are missing.

Individual Years not used for annual statistics if any month in that year has more than 5 days missing.

1929 1.05 1.90 1.65 1.95 0.00 1.75 0.00 0.00 0.35 0.00 0.00 3.20 11.85

1930 6.32 5.85 4.70 0.75 0.30 ----- ----- ----- 0.75 0.25 2.50 ----- 21.42

1931 3.22 1.60 1.80 0.45 1.10 ----- 0.00 0.00 0.00 0.85 2.20 11.90 19.9

1932 4.15 5.22 0.93 0.71 1.31 0.03 0.05 0.02 0.01 0.02 1.13 3.75 17.33

1933 9.98 1.51 3.35 0.30 1.47 0.06 0.02 0.03 0.08 1.43 0.00 7.48 25.71

1934 0.61 6.54 0.02 0.40 0.32 1.32 0.00 0.02 0.25 1.33 3.90 5.95 20.66

1935 6.29 0.79 4.60 6.40 0.05 0.00 0.00 0.69 0.06 2.74 0.66 4.68 20.67

1936 6.30 11.98 1.55 1.69 1.72 0.84 0.53 0.00 0.00 1.10 0.06 7.20 32.97

1937 7.39 7.49 9.49 0.92 0.08 ----- 0.00 0.00 0.01 ----- 2.82 ----- 28.2

1938 7.35 11.91 8.10 2.02 0.23 0.02 0.00 ----- 0.12 3.02 1.36 1.36 23.58

1939 4.71 3.08 3.93 0.25 1.21 0.00 0.00 0.00 1.32 1.07 0.68 1.61 14.78

1940 19.81 10.85 8.21 0.71 ----- ----- 0.12 0.00 ----- 2.09 1.06 12.83 35.87

1941 13.61 14.41 7.61 7.66 1.77 0.22 0.00 ----- 0.03 ----- 2.22 14.86 32.26

1942 6.96 7.18 3.04 4.34 2.50 0.00 0.00 0.00 0.07 1.62 7.97 7.00 40.68

1943 8.80 4.25 7.87 2.01 0.00 0.00 0.00 0.00 0.00 1.58 0.81 3.33 24.4

1944 7.90 8.13 1.41 2.17 1.55 0.51 0.00 0.00 0.00 2.59 8.58 3.62 36.46

1945 2.22 8.58 5.95 0.44 1.13 0.08 0.00 0.00 0.00 2.15 3.43 13.48 37.46

1946 1.73 3.96 3.64 0.00 1.72 0.00 0.04 0.00 0.11 0.38 6.47 2.89 20.94

1947 0.94 3.20 4.01 0.22 0.55 0.40 0.00 0.00 0.00 5.22 1.37 2.61 18.52

1948 1.38 2.77 4.80 5.07 1.39 0.05 0.00 0.04 0.00 0.74 0.70 10.49 22.63

1949 4.23 3.83 8.19 0.02 0.36 0.00 0.03 0.07 0.08 0.05 2.11 4.91 23.88

1950 11.72 7.11 2.48 1.87 0.76 0.03 0.01 0.00 0.35 1.97 11.39 9.35 47.04

1951 5.31 4.20 3.60 1.46 1.00 0.03 0.00 0.04 0.00 1.49 2.11 15.79 35.03

1952 13.60 3.24 5.87 1.38 0.33 0.77 0.00 0.00 0.00 0.00 2.86 7.82 35.87

1953 3.53 0.00 4.10 4.97 0.69 0.22 0.00 0.22 0.00 0.33 3.73 0.73 18.52

1954 4.60 3.79 6.65 2.56 0.64 0.47 0.00 0.34 0.00 0.10 5.61 4.82 29.58

1955 6.58 1.88 0.48 3.58 0.83 0.00 0.00 0.00 0.00 0.05 3.74 21.07 38.21

1956 9.34 1.46 0.26 1.89 1.49 0.00 0.07 0.02 0.28 1.83 0.02 0.96 17.62

1957 5.90 4.90 2.03 1.96 4.03 0.16 0.06 0.05 0.29 5.34 0.97 5.48 31.17

1958 7.70 13.86 7.51 4.47 0.43 0.18 0.00 0.00 0.32 0.06 0.37 0.75 28.14

1959 10.40 7.13 1.01 0.56 0.00 0.00 0.00 0.09 2.71 0.00 0.00 0.78 19.97

1960 8.98 7.03 2.44 1.67 0.39 0.02 0.02 0.02 0.08 0.31 4.35 1.76 27.07

1961 3.92 1.27 3.97 0.04 0.70 0.15 0.00 0.11 0.16 0.05 3.66 2.08 15.11

1962 3.68 11.96 4.70 0.80 0.02 0.04 0.00 0.05 0.31 2.95 0.99 3.70 29.2

1963 7.15 4.91 5.81 7.41 0.55 0.03 0.02 0.06 0.16 1.85 6.72 0.33 35

1964 5.33 0.20 3.26 0.16 0.44 0.37 0.00 0.17 0.20 1.67 3.81 13.06 28.67

1965 3.78 1.71 2.98 3.43 0.02 0.07 0.00 0.11 0.00 0.12 6.93 4.54 23.69

-47916

File last updated on November 4, 2024 a = 1 day missing, b = 2 days missing, c = 3 days, ..etc.., z = 26 or more days missing, A = Accumulations present

Long-term means based on columns; thus, the monthly row may not sum (or average) to the long-term annual value.

MAXIMUM ALLOWABLE NUMBER OF MISSING DAYS : 5

Individual Months not used for annual or monthly statistics if more than 5 days are missing.

Individual Years not used for annual statistics if any month in that year has more than 5 days missing.

1966 2.17 4.72 0.39 0.79 0.10 0.15 0.32 0.10 0.15 0.05 6.17 6.87 21.98

1967 8.74 0.74 7.26 8.26 0.40 1.51 0.00 0.00 0.00 0.13 2.14 3.10 32.28

1968 3.82 4.93 5.64 0.97 0.18 0.00 0.00 0.55 0.00 1.50 4.31 7.27 29.17

1969 14.80 12.01 1.99 2.87 0.08 0.04 0.00 0.00 0.07 1.77 1.34 6.75 41.72

1970 13.03 3.11 3.39 0.23 0.03 0.53 0.00 0.00 0.00 1.24 9.55 8.18 39.29

1971 2.44 1.02 2.45 1.74 0.24 0.00 0.00 0.06 0.32 0.48 3.74 7.48 19.97

1972 1.79 1.81 0.32 1.92 0.03 0.14 0.04 0.00 1.33 3.41 10.54 3.38 24.71

1973 7.84 12.99 5.01 0.05 0.04 0.00 0.00 0.00 0.41 2.71 9.56 6.27 44.88

1974 5.99 2.00 7.35 4.86 0.02 0.31 2.89 0.00 0.00 1.94 1.07 3.91 30.34

1975 1.28 5.72 6.65 2.63 0.00 0.10 0.14 0.85 0.00 3.65 0.49 0.30 21.81

1976 0.32 3.89 1.93 2.11 0.00 0.20 0.01 1.25 1.22 0.46 3.80 2.63 17.82

1977 1.75 1.55 2.24 0.21 0.74 0.07 0.01 0.00 1.35 0.26 1.72 6.09 15.99

1978 11.40 6.13 5.98 5.30 0.01 0.08 0.00 0.00 0.62 0.00 4.48 1.08 35.08

1979 10.06 7.55 3.83 1.29 0.66 0.00 0.20 0.00 0.00 3.45 2.52 6.79 36.35

1980 9.97 8.69 2.02 2.21 0.61 0.17 0.71 0.00 0.00 0.04 0.17 2.57 27.16

1981 7.05 2.62 8.51 0.26 0.35 0.00 0.00 0.00 0.17 1.26 7.05 4.36 31.63

1982 13.38 6.63 7.84 6.05 0.05 0.27 0.00 0.06 1.19 2.50 6.47 2.99 41.38

1983 9.16 9.74 15.16 5.08 0.60 0.00 0.00 0.23 2.00 1.07 8.58 8.14 59.76

1984 0.33 2.40 1.94 1.18 0.11 0.15 0.00 0.00 0.11 3.59 11.06 2.39 23.26

1985 1.71 3.28 6.60 0.42 0.20 0.14 0.13 0.02 0.14 0.92 5.68 3.91 23.15

1986 6.93 12.20 8.24 0.77 0.60 0.00 0.00 0.00 1.74 0.05 0.05 1.68 32.26

1987 3.47 5.28 4.48 0.84 0.00 0.00 0.00 0.00 0.00 0.94 3.05 7.16 25.22

1988 4.44 0.74 0.05 1.74 0.59 0.02 0.00 0.00 0.00 0.30 4.46 7.72 20.06

1989 1.36 1.52 7.00 0.72 0.10 0.02 0.00 0.07 0.87 2.19 1.12 0.05 15.02

1990 2.64 3.33 2.65 0.43 4.11 0.03 0.00 0.00 0.21 0.67 0.47 1.65 16.19

1991 0.81 4.92 10.60 0.80 0.06 0.26 0.02 0.04 0.06 2.26 1.51 4.25 25.59

1992 3.19 11.10 4.35 0.28 0.00 0.55 0.00 0.02 0.00 1.18 0.23 7.10 28

1993 13.85 8.02 3.44 1.37 0.94 0.56 0.00 0.00 0.00 0.61 2.73 4.00 35.52

1994 2.59 8.18 0.74 1.82 1.98 0.00 0.00 0.00 0.06 0.36 4.88 3.24 23.85

1995 17.56 0.47 8.49 5.13 1.34 1.54 0.00 0.00 0.00 0.00 0.19 6.54 41.26

1996 8.40 9.20 3.15 1.58 2.43 0.00 0.00 0.00 0.00 2.44 7.33 13.74 48.27

1997 10.12 0.29 1.26 0.70 0.07 0.19 0.00 0.45 0.01 0.47 9.59 3.67 26.82

1998 15.58 18.63 4.68 3.11 3.87 0.14 0.00 0.00 0.08 0.88 5.30 1.74 54.01

1999 7.44 10.66 4.08 2.97 0.04 0.34 0.00 0.02 0.18 0.29 3.41 0.77 30.2

2000 11.86 14.06 2.41 1.60 1.27 0.19 0.00 0.22 0.31 4.84 1.28 1.04 39.08

2001 5.92 7.00 3.29 1.76 0.00 0.10 0.00 0.02 0.20 0.70 6.28 11.07 36.34

2002 3.73 2.28 3.52 0.35 0.81 0.00 0.01 0.04 0.00 0.00 4.27 15.21 30.22

-47916

File last updated on November 4, 2024 a = 1 day missing, b = 2 days missing, c = 3 days, ..etc.., z = 26 or more days missing, A = Accumulations present

Long-term means based on columns; thus, the monthly row may not sum (or average) to the long-term annual value.

MAXIMUM ALLOWABLE NUMBER OF MISSING DAYS : 5

Individual Months not used for annual or monthly statistics if more than 5 days are missing.

Individual Years not used for annual statistics if any month in that year has more than 5 days missing.

2003 1.85 1.86 1.47 3.50 0.90 0.07 0.00 0.01 0.00 0.31 3.38 9.93 23.28

2004 3.27 5.64 1.34 0.43 0.09 0.01 0.06 0.00 0.02 5.80 2.20 10.28 29.14

2005 5.98 6.26 7.65 3.03 1.34 1.05 0.01 0.02 0.01 0.12 1.86 12.62 39.95

2006 6.37 2.76 10.99 7.00 0.78 0.00 0.00 0.00 0.00 0.14 3.26 4.73 36.03

2007 0.80 5.86 0.33 1.53 0.55 0.00 0.00 0.01 0.38 1.40 0.54 3.83 15.23

2008 12.16 6.10 0.51 0.48 0.00 0.00 0.01 0.00 0.01 0.80 1.94 3.00 25.01

2009 1.84 10.30 2.07 0.42 1.67 0.00 0.00 0.02 0.36 4.08 0.19 4.06 25.01

2010 8.19 5.78 3.17 4.49 0.74 0.00 0.02 0.03 0.01 3.16 4.05 9.40 39.04

2011 2.17 5.75 10.87 0.66 1.53 2.35 ----- 0.06 ----- ----- 2.54 ----- 2.17

2012 ----- 0.94 7.38 3.10 0.06 0.19 0.03 0.00 0.02 0.53 5.56 7.95 25.76

2013 0.90 0.31 1.45 0.93 0.02 0.16 0.03 0.00 0.19 0.07 0.72 0.29 5.07

2014 0.05 7.19 3.76 1.21 0.04 0.02 0.13 0.00 0.92 0.84 3.83 11.49 29.48

2015 0.00 2.85 0.51 1.98 0.10 0.01 0.03 0.03 0.03 0.08 4.42 6.43 16.47

2016 11.80 1.03 7.65 0.89 0.25 0.00 0.01 0.04 0.03 4.89 2.83 7.84 37.26

2017 15.72 12.96 4.48 2.16 0.03 0.10 0.02 0.02 0.06 0.07 2.75 0.18 35.71

2018 5.29 0.32 6.89 3.98 0.04 0.03 0.00 0.00 0.01 0.05 2.40 3.89 9.63

2019 6.69 11.00 7.22 0.69 4.33 0.01 0.05 0.00 0.13 0.00 0.00 13.65 29.43

2020 3.20 0.00 3.34 3.24 1.76 0.00 0.00 0.05 0.00 0.00 0.96 2.65 5.9

2021 7.54 1.63 2.73 0.34 0.00 0.00 0.00 0.00 0.00 5.28 2.21 9.67 17.21

2022 0.69 0.00 0.14 ----- ----- ----- ----- ----- ----- ----- ----- ----- 0

DAVENPORT, CA

Maximum of Precipitation (Inches)

042290

File last updated on November 4, 2024 a = 1 day missing, b = 2 days missing, c = 3 days, ..etc.., z = 26 or more days missing, A = Accumulations present

Long-term means based on columns; thus, the monthly row may not sum (or average) to the long-term annual value.

MAXIMUM ALLOWABLE NUMBER OF MISSING DAYS : 5

Individual Months not used for annual or monthly statistics if more than 5 days are missing.

Individual Years not used for annual statistics if any month in that year has more than 5 days missing.

Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

1960 ----- ----- ----- ----- ----- ----- ----- ----- 0.00 0.46 0.95 0.36 -----

1961 2.12 0.22 0.99 0.57 0.55 0.10 0.02 0.02 0.17 0.03 1.42 1.03 2.12

1962 2.87 1.72 1.00 0.46 0.04 0.07 0.02 0.09 0.14 1.90 0.41 2.04 2.87

1963 1.82 2.62 2.23 1.23 0.40 0.02 0.01 0.02 0.26 1.05 2.27 0.25 2.62

1964 1.86 0.14 1.27 0.45 0.16 0.70 0.02 0.09 0.04 1.53 2.00 1.83 2.00

1965 1.33 0.95 1.14 1.01 0.00 0.05 0.00 0.05 0.00 0.19 2.66 1.38 2.66

1966 2.43 1.02 0.18 0.43 0.08 0.08 0.04 0.09 0.28 0.00 1.85 3.03 3.03

1967 2.80 0.31 1.18 1.38 0.10 1.38 0.00 0.00 0.00 0.30 0.50 0.77 2.80

1968 2.25 2.75 1.44 0.63 0.24 0.00 0.00 0.33 0.08 0.64 1.63 1.86 2.75

1969 2.79 1.92 0.52 0.93 0.00 0.23 0.00 0.03 0.02 0.91 0.76 0.89 2.79

1970 2.12 0.80 1.48 0.12 0.03 0.42 0.00 0.00 0.00 0.38 2.40 1.60 2.40

1971 0.55 0.42 1.33 0.59 0.66 0.00 0.00 0.13 0.26 0.00 1.44 2.09 2.09

1972 0.58 0.80 0.11 0.66 0.00 0.44 0.00 0.00 1.64 1.97 2.04 0.42 2.04

1973 1.70 2.29 1.32 0.00 0.00 0.02 0.00 0.00 0.21 1.23 2.26 1.42 2.29

1974 1.83 0.83 2.11 3.03 0.00 0.27 1.85 0.00 0.00 0.76 0.47 2.09 3.03

1975 0.99 0.77 1.16 0.38 0.00 0.12 0.11 0.80 0.09 1.06 0.36 0.41 1.16

1976 0.32 1.06 0.59 0.67 0.08 0.06 0.00 0.44 0.38 0.47 1.00 1.61 1.61

1977 1.12 0.40 1.72 0.34 0.58 0.03 ----- ----- ----- ----- ----- ----- -----

Chapter 2

2–7(210-VI-TR-55, Second Ed., June 1986)

Technical Release 55 Urban Hydrology for Small Watersheds

Estimating Runoff

Table 2-2c Runoff curve numbers for other agricultural lands 1/

Curve numbers for --------------------------------------- Cover description -------------------------------------- ------------ hydrologic soil group ---------------

Hydrologic Cover type condition A B C D

Pasture, grassland, or range—continuous Poor 68 79 86 89 forage for grazing. 2/ Fair 49 69 79 84

Good 39 61 74 80

Meadow—continuous grass, protected from — 30 58 71 78 grazing and generally mowed for hay.

Brush—brush-weed-grass mixture with brush Poor 48 67 77 83 the major element. 3/ Fair 35 56 70 77

Good 30 4/ 48 65 73

Woods—grass combination (orchard Poor 57 73 82 86 or tree farm). 5/ Fair 43 65 76 82

Good 32 58 72 79

Woods. 6/ Poor 45 66 77 83 Fair 36 60 73 79

Good 30 4/ 55 70 77

Farmsteads—buildings, lanes, driveways, — 59 74 82 86 and surrounding lots.

1 Average runoff condition, and Ia = 0.2S.

2 Poor: <50%) ground cover or heavily grazed with no mulch.

Fair: 50 to 75% ground cover and not heavily grazed.

Good: > 75% ground cover and lightly or only occasionally grazed.

3 Poor: <50% ground cover.

Fair: 50 to 75% ground cover.

Good: >75% ground cover.

4 Actual curve number is less than 30; use CN = 30 for runoff computations.

5 CN’s shown were computed for areas with 50% woods and 50% grass (pasture) cover. Other combinations of conditions may be computed from the CN’s for woods and pasture.

6 Poor: Forest litter, small trees, and brush are destroyed by heavy grazing or regular burning.

Fair: Woods are grazed but not burned, and some forest litter covers the soil.

Good: Woods are protected from grazing, and litter and brush adequately cover the soil.

Hydrologic Soil Group—Santa Cruz County, California

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

11/4/2024

573700 573800 573900 574000 574100 574200 574300 574400 574500 574600 574700 574800

573700 573800 573900 574000 574100 574200 574300 574400 574500 574600 574700 574800

36° 59' 38'' N

2°

0'

1' ' W

36° 59' 38'' N

2°

' 3

3' ' W

36° 59' 13'' N

2°

0'

1'

' W

36° 59' 13'' N

2°

' 3

3' ' W

N

Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 10N WGS84 0 250 500 1000 1500

Feet 0 50 100 200 300

Meters Map Scale: 1:5,430 if printed on A landscape (11" x 8.5") sheet.

Soil Map may not be valid at this scale.

MAP LEGEND MAP INFORMATION

Area of Interest (AOI) Area of Interest (AOI)

Soils Soil Rating Polygons

A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating Lines A

A/D

B

B/D

C

C/D

D

Not rated or not available

Soil Rating Points A

A/D

B

B/D

C

C/D

D

Not rated or not available

Water Features Streams and Canals

Transportation Rails

Interstate Highways

US Routes

Major Roads

Local Roads

Background Aerial Photography

The soil surveys that comprise your AOI were mapped at 1:24,000.

Warning: Soil Map may not be valid at this scale.

Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale.

Please rely on the bar scale on each map sheet for map measurements.

Source of Map: Natural Resources Conservation Service Web Soil Survey URL:

Coordinate System: Web Mercator (EPSG:3857)

Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required.

This product is generated from the USDA-NRCS certified data as of the version date(s) listed below.

Soil Survey Area: Santa Cruz County, California Survey Area Data: Version 18, Sep 8, 2024

Soil map units are labeled (as space allows) for map scales 1:50,000 or larger.

Date(s) aerial images were photographed: Feb 17, 2021—Feb 21, 2021

The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident.

Hydrologic Soil Group—Santa Cruz County, California

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

11/4/2024

Hydrologic Soil Group

Map unit symbol Map unit name Rating Acres in AOI Percent of AOI

104 Baywood loamy sand, 0 to 2 percent slopes

A 6.5 9.4%

116 Bonnydoon loam, 5 to 50 percent slopes, MLRA 4B

D 7.5 10.7%

118 Bonnydoon-Rock outcrop complex, 50 to 85 percent slopes

D 0.1 0.1%

128 Dune land 4.4 6.3%

130 Elder sandy loam, 2 to 9 percent slopes, MLRA

A 1.8 2.5%

133 Elkhorn sandy loam, 2 to 9 percent slopes

C 11.1 16.0%

134 Elkhorn sandy loam, 9 to 15 percent slopes

C 0.6 0.9%

178 Watsonville loam, thick surface, 0 to 2 percent slopes

D 27.0 38.7%

179 Watsonville loam, thick surface, 2 to 15 percent slopes

D 6.2 8.9%

Totals for Area of Interest 69.8 100.0%

Hydrologic Soil Group—Santa Cruz County, California

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

Description

Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms.

The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows:

Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission.

Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture.

These soils have a moderate rate of water transmission.

Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission.

Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission.

If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes.

Rating Options

Aggregation Method: Dominant Condition

Component Percent Cutoff: None Specified

Tie-break Rule: Higher

Hydrologic Soil Group—Santa Cruz County, California

Natural Resources Conservation Service

Web Soil Survey National Cooperative Soil Survey

CALC'D BY:

AM

SUBJECT: REV'D BY:

Monterey Bay Sanctuary Scenic Trail IM

DATE:

Hydrology 11/2/2024

PROJECT NUMBER

Water Balance Analysis

Drainage Area (E1) 3.05 ac Reference:

Drainage Area (E2) 13.67 ac LIDAR elevation delineation.

Runoff Coefficient (CN) 48.00 TR-55 Table 2-2c (Brush in good condition)

Potential Maximum Retention (S) 10.83 TR-55 Equation 2-4

Initial Abstraction (Ia) 2.17 in TR-55 Equation 2-2 acft cuft acft cuft

January 5.40 0.74 0.19 8205 0.84 36776

February 4.66 0.46 0.12 5146 0.53 23063

March 3.97 0.26 0.07 2849 0.29 12769

April 1.95 0.00 0.00 0 0.00 0

May 0.56 0.00 0.00 0 0.00 0

June 0.27 0.00 0.00 0 0.00 0

July 0.11 0.00 0.00 0 0.00 0

August 0.13 0.00 0.00 0 0.00 0

September 0.35 0.00 0.00 0 0.00 0

October 1.48 0.00 0.00 0 0.00 0

November 3.90 0.24 0.06 2633 0.27 11799

December 4.79 0.51 0.13 5662 0.58 25376

Precipitation (in)Month

Drainage Area (E1) Runoff

Volume

Drainage Area (E2) Runoff

Volume Runoff

Volume (in)