Rebuttal Report for City of Durango, Case No. 2006CW9

• Description: Durango RICD
• State: CO
• Basin: San Juan/Dolores
• Water Division: 7
• Date: 2/2/2007
• Author: RPI Consulting
• Title: Rebuttal Report for City of Durango, Case No. 2006CW9
• Water Supply Pro - Doc Type: Report/Study

POND, LAWN, AND GARDEN USE
The 820 -2500 AF Pond Lawn and Garden use portion of the estimate for the 30,000 AF
I
carve -out in Table D is based on a number of assumptions and no derivation, citation, or
methodology underlying them is offered. However, 2 of these assumptions can be evaluated
using available data:
La Plata Land Use Plans Allow for 650 lots over 5 acres
25% of lots will have ponds
In Animas River Basin Future Residential Development and Water Demand Study, RPI Consulting
conducted a GIS based future residential development analysis for La Plata County summarized on
pages 4 -9 of the report. Estimating future residential development involved an 18 step methodology
that included the assignment of maximum and minimum densities allowed under La Plata County
plans and zoning to each parcel in the study area. Table 8 lists the land use designations contained in
the North County, Animas Valley, West Durango, Florida, and Junction Creek Planning Areas that
have minimum lot sizes of 5 or more acres. A GIS database query isolated the parcels with these land
use designations. Then the total future units needing a water right (summarized in Animas River Basin
Future Residential Development and Water Demand Study, Table 2 and Map 3) were summed to yield 303
potential units greater than or equal to 5 acres. This is less than half of the 650 units assumed in
Table D of the Harris report.
Table 8 - La Plata County Land Use Designations with Minimum Acres per Unit >= 5 acres
Source: http:// Co .laplata.co.us /planlplansum.htm
A substantial portion of La Plata County is covered by GIS pond coverage available from the
US Fish and Wildlife Service National Wetlands Inventory. This data combined with La
Plata County's parcel layer allowed RPI to estimate the percentage of existing residential
parcels 5 acres or greater that have ponds in La Plata County. See Table 9 for a numeric
summary and Map 1 for a geographic representation.
Table 9 - Pond Rate in West La Plata County
Maximum
Minimum
• West La Plata County Residential Lots > 5 Acres
Acres
Acres
Land Use Category
Per Unit
per Unit
10 Acre Single Family
10
10
15 Acre Single Family
15
15
5 Acre Single Family
5
5
Ag /Residential 35
35
35
Ag /Rural Residential
20
10
Ag/Timber /Public Recreation
35
35
Ag/Timber /Recreation
35
35
Country Tourist /Dude Ranch
10
10
Residential 10
10
10
River Corridor
35
35
Source: http:// Co .laplata.co.us /planlplansum.htm
A substantial portion of La Plata County is covered by GIS pond coverage available from the
US Fish and Wildlife Service National Wetlands Inventory. This data combined with La
Plata County's parcel layer allowed RPI to estimate the percentage of existing residential
parcels 5 acres or greater that have ponds in La Plata County. See Table 9 for a numeric
summary and Map 1 for a geographic representation.
Table 9 - Pond Rate in West La Plata County
Summary: According to RPI's analysis, two key assumptions used in the Harris report to
estimate future Pond, Lawn, and Garden water use result in over estimation of water demand.
Quantity
Source
• West La Plata County Residential Lots > 5 Acres
587
ftp :HftP.laplata.co.us /shapefiles/
• of Ponds
71
http: / /wetiandswms.er.usgs.gov
• West La Plata County Residential Lots > 5 Acres Parcels with Ponds
63
GIS Analysis, See Map 1
of Residential Lots >= 5 Acres with Ponds
11%
= 63 / 587
Summary: According to RPI's analysis, two key assumptions used in the Harris report to
estimate future Pond, Lawn, and Garden water use result in over estimation of water demand.