DDW-2025-003668

Irrigation Demands & Map
Additional Notes
Capacity Calculations
Does the water system provide fire protection?
System Name:
gpm
Zone
Peak Day
Avg Year
Storage
Demand
Reqmt
Peak
Total
Instantaneous
Water Rights
Storage
(gpm)
(ac-ft/yr)
(gallons)
Requirement
Source
zone
Difference:
gal
(gpm/irr. ac)
Avg. Yr.
(ac-ft/yr
per irr. ac.)
(gal/irr. ac)
IRRIGATION DEMANDS
(to be added to indoor and fire flow demands)
Is the drinking water used for outdoor irrigation?
- - - - - - - - -
- - - - - - - -
- - - > > >
(gpd/ERC)
Total irrigated acreage of other connections.
Required Fire Suppression Storage (gallons)
Irrigation zone
(gallons/ERC)
Modern Recreation Camp
GPD/person
System Number:
Existing Sources:
Existing Storage:
Irrigation Demands & ERCs
(used in calculations on DDW Calculation sheet)
Total Source Capacity
ST001
ST002
(in gallons)
Total Storage Capacity
(in gallons per minute)
1. Indoor Water Use
2. Outdoor Water Use
3. Fire Flow Requirement
Does this system have adequate storage capacity per R309-510-8?
Required Source Capacity:
Required Storage Capacity:

Per ERC
Total Equivalent Residential Connections (ERCs)
Does this system have adequate source capacity per R309-510-7?
% of Req'd Capacity:
ERCs
ERCs
ERCs of other connections
Average irrigated acreage per residential connection

Residential ERCs using drinking water for irrigation
Percentage of Residential ERCs using DW for irrigation
Enter the green cells only.
Number of residential connections
Existing Residential Connections
Number of other connections - - -
Max. ERC allowed (for indoor use only)
Total Water System Requirements (= indoor use + outdoor use + fire flow demand)
MINIMUM REQUIREMENTS FOR INDOOR WATER USE
MINIMUM REQUIREMENTS FOR OUTDOOR WATER USE
Equivalent Residential Connection Calc.
MINIMUM REQUIREMENTS FOR WATER SYSTEM
Division of Drinking Water Water System Capacity Calculation Sheet (revised June 23, 2011)
MINIMUM REQUIREMENTS FOR INDOOR USE
Semi-Developed Camp w/o flush toilets
Roadway Rest Stop w/ flushometer valves
RV Park
N/A
Gallon/site or pad
Facility Type
ERC/1000 vehicles served
# of Vehicles served
Source (GPD/vehicle)
*Number of people per camp site
Storage (Gal./vehicle)
(Use this additional sheet to document calculations related to the DDW Calculation sheet, such as ERCs.)
(Enter additional notes here.)
Additional Notes
Map Zones
(Example: water use of 2 factory is equivalent to 30 homes.)
Maximum fire suppression demand for water system or pressure zone (gpm)
Maximum fire suppression duration for water system or pressure zone (hours)
- - - - - - - - - - -
- - - - - - - - - -
Non-Community Water Systems, ERCs for Indoor Water Use (*See R309-510, Tables 510-1, 2, and 4, for other facility type calc.)
IPS points may be assessed for lacking adequate source capacity to meet peak day and/or average yearly flow requirements.
IPS points may be assessed for lacking adequate storage capacity.
Number of Obligated Future ERCs
Total Projected Number of ERCs
No outdoor irrigation.
Fire flow through evaporation pond based on fire inspection report. Keep pond full at all times.
Restaurant (per seat)
# of Sites or Seats
GPD/person or seats*
Calculated GPD/site or restaurant
ERC/site or restaurant
US Magnesium
23039
150K Demin Tank
1 MG Tank (Raw)
WS004

Skull Valley (Wells A,B,D)
Industrial buildings per 8 hour shift per employee - 35 gpd. Current population in waterlink is 450. Assume all employees for determining capacity. Approximately 15,750 gallons per day.
Divide by 800 gpd/ERC. Therefore, 19.7 ERCs is utilized.
August 2003 - DDW Revision
US Magnesium
23039
3.00
3.39
1.00
2.00
3.00
4.00
5.00
6.00
NO ZONE
1.66
1.00
2.00
3.00
4.00
5.00
6.00
NO ZONE
2528.00
1.00
2.00
3.00
4.00
5.00
6.00
NO ZONE
1.00
2.26
1.17
1782.00
4.52
2.00
2.80
1.23
1873.00
5.60
3.00
3.39
1.66
2528.00
6.78
4.00
3.96
1.87
2848.00
7.92
5.00
4.52
2.68
4081.00
9.04
6.00
4.90
3.26
4964.00

9.80

US Magnesium
23039
Page of
0.00
1.00
19.70
19.70
800.00
10.94
24.00
60.00
400.00
7880.00
0.45
8.87
0.00
0.00
1.00
0.00
2.00
3.00
3.00
4.00
5.00
6.00
0.00
24.00
60.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
60.00
800.00
10.94
400.00
7880.00
0.45
8.87
5250.00
10.94
479.70
5239.06
150000.00
7880.00
19.04
142120.00
60.00
0.00
30.00
2.00
0.00
0.00
800.00

0.00
0.00
35.00
0.00
17.50
2.00
0.00
0.00
800.00
0.00
0.00
5.00
0.00
2.50
2.00
0.00
0.00
800.00
0.00
0.00
100.00
50.00
0.13
800.00
0.00
0.00
0.00
7.00
3.50
2.00
8.75
1000.00
800.00
0.00
0.00
1000.00
US Magnesium
0.00
5250.00
0.00
5250.00
9450.00
800.00
1440.00
150000.00
0.00
150000.00
Yes
No
Yes
No
Enter number of non-residential connections (e.g., 2 factory connections).
Convert "Number of other connections" (Cell E9) to ERCs here. (ERCs of other connection = peak day demand of other connections / 800 gal per day)
Enter estimated irrigated acre per residential lot here.
Enter total irrigated acres of other connections here.

Enter fire flow in gpm.
Enter duration in hours.
Linked to Cell I99 below.
Select Irrigated Zone # from the list (see "Irrigation Demands & Map" tab on the bottom of the screen).

Linked to Cell I118 below.
If applicable, enter number of people per camp site here.
Negative number means (1) additional source capacity is needed , and (2) IPS points should be assessed.
Negative number means (1) additional storage volume is needed, and (2) IPS points should be assessed.
If you need to calculate projected future demand (including existing & future connections), insert this number to Cell I8 "Number of residential connection."
Linked to Cell I8 above.
Diaphragm or air pressure tanks shall not be considered effective storage volume for community systems or NTNC with significant demand.
Linked to Cell C51 above.
Linked to Cell E51 above.