Idaho’s Experience with Random Design using NHD

Intermittent streams and other considerations

Mary Anne Nelson, Michael McIntyre, Michael Edmondson, Glen Pettit

Idaho Department of Environmental Quality

Sampling Design• Sample Population

– All perennial, wadeable streams– 1:100,000 scale

• Sampling Frame– NHD supplied to ORD (Corvallis, OR)– Strahler order (1-5)– DEQ Region

• Survey Design– Generalized random tessellation stratified

survey design for a linear network

• Multi-Density Categories– DEQ Regions (6)– Strahler Order

• 1&2 (50%)• 3 (30%)• 4&5 (20%)

• Panels: 5 panels of 50 sites statewide, 1 panel monitored each year

• 500% Oversample

Sampling Design

Site Selection • Wadeable vs. Non-Wadeable

– 4th order or less– Less than 15 m average wetted width– Less than 0.4 m average depth at base flow

• Inaccessible– Minimum 2 hour hike to access– Safety issues

• Dry• Wetland/No Flow• Denied Access• Impoundments

– Beaver dams• Map Error

Where rubber meets the road

Accessibility

Flow

Random Monitored

Target Monitored

Target Rejected

Repeat

Reference

Random Rejected

Monitoring Effort in 200456 Random Sites (8.5%)220 Rejected Random Sites (33.38%)238 Target Sites (36.12%)104 Rejected Target Sites (15.78%)6 Random Repeat (0.91%)35 Reference Trend (5.31%)

Total Sites 65942.79% Effort in

Random Sites57.21 % Effort in

Targeted Sites

50 Primary Sites250 Secondary Sites56 Monitored Random Sites

2004 Site Selection Results

Of the 50 Primary Sites11 Monitored32 Rejected7 unknown

2004 Rejected Random Sites

116 Not Visited 104 Visited

54 INACCESSIBLE 69 DRY29 ACCESS DENIED 10 NON WADEABLE15 NON WADEABLE 7 NO FLOW

8 DRY 4 ACCESS DENIED4 NO FLOW 4 WETLAND3 T & E SPECIES 3 ALTERED1 ALTERED 3 INACCESSIBLE1 MAP ERROR 3 MAP ERROR

1TEMP

INACCESSIBLE 1 NORMAL

220 Rejected Sites in 2004

Random Monitored

Random Rejected

Target Monitored

Target Rejected

Repeat

Reference

Monitoring Effort in 200549 Random Sites (12.16%)187 Rejected Random Sites (46.40%)109 Target Sites (27.05%)22 Rejected Target Sites (5.46%)6 Random Repeat (1.49%)30 Reference Trend (7.44%)

Total Sites 40360.05 % Effort in

Random Sites39.95 % Effort in

Targeted Sites

89 Not Visited 98 Visited30 INACCESSIBLE 58 DRY26 DRY 9 DENIED ACCESS11 ACCESS DENIED 9 HIGH FLOW10 LIMITED ACCESS 8 NO FLOW/WETLAND9 NON-WADEABLE 7 INACCESSIBLE2 NO FLOW 3 UNKNOWN1 NO DATA 2 BEAVER COMPLEX

1 LIMITED ACCESS1 NO RIFFLES

2005 Rejected Random Sites

187 Rejected Sites in 2005

Dry Sites in Idaho

Monitored Sites in Idaho

Precipitation

2004 Monitored

Sites

2005 Monitored

Sites7-10” 3 010-20” 10 9

20-30” 19 17

30-40” 14 19

40-50” 7 3

50-60” 2 1

77 Sites Rejected in 2004 as Dry84 Sites Rejected in 2005 as Dry

Public Lands

Sites on Private Land

Monitored

Access Denie

d2004 18 332005 15 20

Sites on Public Land2004 382005 34

Land Type AcresFederal 33,764,66

4Private 16,387,87

3State 2,615,417

Breakdown of Land Ownership

Private Public

Land % 30.99% 68.79%

2004 Sites Monitored 32.14% 67.86%

2005 Sites Monitored 30.61% 69.39%

Landuse Patterns

2004 2005Dryland Ag 4 0

Forest 35 31Irrigated-Gravity 3 2

Irrigated-sprinkler

3 1

Rangeland 13 13

Urban 0 2

GIS Site Analysis• GIS coverages

– Precipitation– Land Use

• Satellite imagery – NAIP imagery– Vegetative Cover

• Catchment area– ArcGIS Spatial Analyst– USGS StreamStats

Conclusions• To achieve the required 50 sites/year,

roughly 200 sites were rejected– 31 % of sites are dry– 23 % of sites are inaccessible

• Need to improve NHD coverage to address intermittent and ephemeral waters

• Working on low-flow model with USGS• Assessment of these sites to be carried out

in May 06 for inclusion in the 06 integrated report