U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3397

Plate 2

Any use of trade, product, or firm names in this publication is for 

descriptive purposes only and does not imply endorsement by the 

U.S. Government.

This map was printed on an electronic plotter directly from digital 

files. Dimensional calibration may vary between electronic 

plotters and between X and Y directions on the same plotter, and 

paper may change size due to atmospheric conditions; therefore, 

scale and proportions may not be true on plots of this map.

Digital files available at https://doi.org/10.3133/sim3397 or 

https://pubs.usgs.gov/sim/3397/. Data release, boosted 

regression tree (BRT) model method, and model fit statistics are 

available at https://doi.org/10.5066/F7T151S1. Information 

regarding methodology available at 

https://doi.org/10.1016/j.jhydrol.2017.01.014.

Suggested citation: Rosecrans, C.Z., Nolan, B.T., and Gronberg, 

J.M., 2018, Spatial distribution of predicted probabilities for 

selected dissolved manganese threshold events, sheet 2 in Maps 

showing predicted probabilities for selected dissolved oxygen and 

dissolved manganese threshold events in depth zones used by the 

domestic and public drinking water supply wells, Central Valley, 

California: U.S. Geological Survey Scientific Investigations Map 

3397, 2 sheets, various scales, https://doi.org/10.3133/sim3397. ISSN 2329-132X (online)

https://doi.org/10.3133/sim3397

Spatial Distribution of Predicted Probabilities for Selected 

Dissolved Manganese Threshold Events

Maps Showing Predicted Probabilities for Selected 

Dissolved Oxygen and Dissolved Manganese Threshold 

Events in Depth Zones Used by the Domestic and Public 

Drinking Water Supply Wells, Central Valley, California

By

Celia Z. Rosecrans, Bernard T. Nolan, and Jo Ann M. Gronberg

2018

42°

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40°

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N N Base modified from U.S. Geological Survey Principal Aquifers of

the 48 Conterminous United States, Hawaii, Puerto Rico, and the 

U.S. Virgin Islands (https://water.usgs.gov/GIS/metadata/usgswrd/

XML/aquifers_us.xml), Groundwater Availability of the Central 

Valley Aquifer, California (https://pubs.usgs.gov/pp/1766/), and 

other Federal digital data, various scales; Albers Equal-Area Conic 

projection, standard parallels are 29°30" N. and 45°30" N.; North

American Datum of 1983

Base modified from U.S. Geological Survey 

digital data, various scales; Albers EqualArea Conic projection, standard parallels 

are 29°30" N. and 45°30" N.; North

American Datum of 1983

50 0 25 50 MILES

SCALE 1:2,400,000

25

50 25 0 25 50 KILOMETERS

EXPLANATION

Water table below prediction 

 depth (4spring 2000)

EXPLANATION

Principal aquifer units 

Basin and Range basin-fill

Basin and Range carbonate-rock 

California Coastal Basin

Central Valley aquifer system

Other rocks

Pacific Northwest

 basaltic-rock

Pacific Northwest

 basin-fill

Study area boundary

Prediction model boundary

Boosted regression tree (BRT)

 training wells (n=812)2

Boosted regression tree

 hold-out wells (n=1,835)3

DOMESTIC-SUPPLY DEPTH ZONE1

(100 feet below land surface)

PUBLIC-SUPPLY DEPTH ZONE1

(325 feet below land surface)

Predicted probability of event

CALIFORNIA PRINCIPAL AQUIFERS

0 50 MILES

SCALE 1:4,100,000

50

50 0 50 KILOMETERS

Dissolved manganese event: 

>50 micrograms per liter

Dissolved manganese event:

>150 micrograms per liter

Dissolved manganese event: 

>300 micrograms per liter

0.0 to 0.1

>0.1 to 0.2

>0.3 to 0.4

>0.4 to 0.5

>0.6 to 0.7

>0.7 to 0.8

>0.9 to 1.0

>0.2 to 0.3 >0.5 to 0.6 >0.8 to 0.9

Prediction model

 boundary

1

Domestic and public supply depth zones represent median well depths of the training dataset applied to the boosted regression tree (BRT) model that were stratified into shallow and deep drinking water supply depths, respectively, 

based on previous work. See data release link for summary of details and citation.

2

BRT models were trained on wells with depth data and required water-quality data for the 1993–2014 model period.

3

The hold-out wells were used to evaluate model predictive performance of trained BRT models.

4

Data from Faunt, C.C., ed., 2009, Groundwater availability in the Central Valley aquifer, California: U.S. Geological Survey Professional Paper 1766, 225 p.