The Role of Wetland, Riparian, and Floodplain Water Storage

in Montana’s Water Supply Initiative

in the context of a warming climate

Montana Wetland Council Meeting3-26-14

Lynda Saul, MDEQ Bruce Sims, USFS

Values

Wetlands feed downstream waters, mitigate floodwaters, recharge groundwater supplies, remove pollution, provide fish and wildlife habitat, and extend the periods of available water.

Climate Change Sets the Context global temperatures are increasing

In 2010, global temperatures continued to rise. A new analysis from the Goddard Institute for Space Studies shows that 2010 tied with 2005 as the warmest year on record and was part of the warmest decade on record. (Image credit: NASA/Earth Observatory/Robert Simmon)

Glacial Retreat in Glacier National ParkPredictions suggest all glaciers in Glacier National Park will have melted by

2030.Should the name then be changed to Glaciated National Park?

River flows in Montana depend mostly on snow pack, infiltration of melted snow into soil surfaces, and ground water movement to streams.

Snow packs may be melting earlier. Total water in the snow packs may be

on the decline.

Throughout western United States – 72% of stations show a decline in April 1 snow water equivalent.

Klos et al., 2012. Indicators of Climate Change in Idaho: The intersection of biophysical change with social perception across a diverse landscape. Paper presented at the Pacific Northwest Climate Conference, Boise, Idaho, 10/02/2012.

Snow Water Equivalent Trends

Declining summer flows of Rocky Mountain rivers: Changing seasonal hydrology and probable impacts on Floodplain forests

Steward B. Rood, Jason Pan, Karen M. Gill, Carmen G. Franks, Glenda M. Samuelson, Anita Shepherd

Journal of Hydrology 2008

Earlier runoff may force construction of more storage reservoirs & heavier reliance on ground water.

Encouraging natural riparian floodplains and wetlands “natural infrastructure” can complement built infrastructure or even preclude the need for new construction.

low Regime, and scale.

Percentage of increase (relative to 1950 to 2003) in median area burned for Western United States ecoprovinces for a 1 °C temperature increase. Color intensity is proportional to the magnitude of the projected increase in area burned (PNW=GTR-870, Peterson, D, and J.S. Littell).

Fire even without a warming climate can cause earlier snow melt…Copper Bottom snow water equivalent as compared to other Snotel sites

before fire in 2000 vs. Copper Bottom after fire in 2006NRCS figures from Scott Oviatt

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Can forests be managed to augment water yield?

Multiple studies show that total discharge increases from relatively small research watersheds are statistically significant when ~20 to 25% of a basal area is removed from forests.

•Basal area reduction may happen by mechanical treatment, wind, insect and disease, or by fire.• Insects and fire are now reducing basal area

on 10s of thousands of acres.

•Duration of water yield increase is related to the vegetative recovery rate.

Middle Fork Boise River Watershed Area - 830 square miles45% burned between 1992 & 2003

Runoff increase of ~5% is attributed to fires.

Runoff had declined ~18% since 1948. Basin scale flooding did not increase.

Luce and others, USDA Forest Service RMRS-GTR-290. 2012.

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Farnes, Phillip E., Ward W. McCaughey, Katherine J. Hansen. 1995. Hydrologic and Geologic Characterization of Tenderfoot Creek Experimental forest, Montana. U.S.D.A. Forest Service Intermountain Research Station and Montana State University, Department of Earth Sciences. Final report RJVA-INT-92734.

Water Yield

Farnes, Phillip E., Ward W. McCaughey, Katherine J. Hansen. 1995. Hydrologic and Geologic Characterization of Tenderfoot Creek Experimental forest, Montana. U.S.D.A. Forest Service Intermountain Research Station and Montana State University, Department of Earth Sciences. Final report RJVA-INT-92734.

Effects of Alternative Silvicultural Treatments on Snow Accumulation in Lodgepole Pine Stands,

MontanaS.W.Woods, W. Mcaughey, R.Ahl, and J. Sappington

Western Snow Conference, 2004.

~60% of basal area was removed using two treatments in the Tenderfoot Creek Experimental Forest and compared against the uncut control: Even thinning Group-retention thinning (<2 hector

corridor-like openings)

Results from Woods and Others

Even thinning treatment significantly increased snow water equivalent, up to 35% as compared to the control.

Group retention did not significantly increase snow water equivalent. Wind scour is likely the reason, some bare

areas were observed. Wind effects extended into uncut areas. However, areas protected from scour

melted the most slowly (likely a snow fence effect).

How Much Water Can a Floodplain or Wetland Hold?

Porosity (the amount of void space in rock or soil) varies depending on geology and/or soil type. 10% - 20% for glacial till 25% - 50% for well-sorted sands or

gravels 33% - 60% for clay

Brooks and others. 1991. Hydrology and The Management of Watersheds. Iowa State Univ. Press. Pg. 89 & 91.

Binarche Creek RNA

Elkhorn Creek Riparian Wetland Beaverhead-Deerlodge National Forest

Upper Yellowstone River above Yellowstone Lake

Pete Bengeyfield photo

Missouri River Floodplain Cotton Wood Regeneration following

June 2011 Snowmelt Runoff

Clark Fork River Flooding Missoula, June 2011

Tower Street MissoulaJune 2011

Binarche RNA Beaver Dam

from Google Earth Scott Dyer Rio Cibola, Santa Fe NF

Discharge before and after failure of a beaver dam shows the water table dropped about 8 cm during 14 hours after of the dam failed, water table before

dam failure. This water level is suitable for persistent wetlands formation before dam failure.

Westbrook et.al. WATER RESOURCES RESEARCH, VOL. 42, 2006

Examples of beaver-influencd channel form. Photos a, c, and e show channel avulsions or splits where an abandoned beaver dam is present.

Photos b and d show island formation at the site of an abandoned beaver dam. Photo f shows a bank reinforced by beaver-chewed wood, possibly an

abandoned dam, which caused a sharp meander bend. White arrows indicate main flow direction.

From: Polvi and Wohl, Earth Surf. Process. Landforms 37, 332–346 (2012)

From Polvi and Wohl Earth Surf. Process. Landforms, Vol. 37, 332–346 (2012)

Some Benefits of Beaver Dams:

increase floodplain accessibility to flows,

raise water tables & increase water storage,

increase the extent of riparian & wetland vegetation,

increase pool frequency and depth, increase stream sinuosity and storage

of sediment, and lower stream temperatures.Michael M. Pollock and others, 2012. Using Beaver to Reconnect Floodplains and Restore Riparian Habitat in an Incised Stream. AWRA 2012 Specialty ConferenceStudy done in Bridge Creek, a tributary to the John Day River in eastern Oregon

Water Quality Benefits of Riparian Areas

Multiple studies have reported nitrate removal efficiencies > 90% in riparian zones (Hill, 1996; Vidon and Hill, 2006).

Riparian areas may also limit transport of other water quality contaminants such as: sediment, ammonium, soluble reactive phosphorus, sulfate, dissolved organic nitrogen, dissolved organic carbon, and some pesticides.

Vidon, Phillippe Craig Allen, and Richard Lowrance. 2008. Generalizing and others Riparian Zone Function at the Landscape Scale. Water Resources Impact Vol. 10, Number 3

With so many unknowns due to climate change, monitoring and adaptive management becomes

crucial.

Needs:

1. increased education both inside and outside land management agencies,

2. set up effective monitoring of key indicators,

3. identify areas of vulnerability,4. quantify benefits and costs of

addressing vulnerabilities, and5. put in place mechanisms to adapt our

management to changing conditions.

Management Adaptations for National Forests

Anticipate increased likelihood of continued warming, severe drought, increased wildfire, and more flooding.

Increase wildland fire use, continue fuels treatments in priority areas, and repeat at appropriate intervals.

Create a watershed restoration program that has the ability and funding to react in a timely manner.

Design all facilities for the likelihood of higher more frequent floods and debris torrents. National Forests have been reducing the miles of

road system, improving fish passage, and upsizing culverts.

Possible Adaptations to Ensure Water Supplies

More storage facilities to capture earlier snow melt may be inevitable, but first: provide water storage through natural

infrastructure; increase efforts to identify and protect flood

plains and wetlands; maintain healthy flood plains accessible to

flood flows; plant drought tolerant crops; and encourage beavers, nature’s wetland/flood

plain developer and flood flow mitigation specialist.

Example of Riparian RestorationWillow Planting - Pueblo Canyon Santa Fe NF, 2008In this example both channel narrowing and aggradation have

occurred. Eventually beaver could establish a population once there is sufficient willow for food and dam construction.

Resiliency

Flood plains and wetlands can be quite resilient following wildfires or other disturbances because:

generally resistant to wildfire or flooding and quick to recover;

may mitigate post fire flooding and debris torrents by spreading out flows and capturing sediment and debris;

benefit/cost ratios of protecting, enhancing or developing floodplains and wetlands are potentially huge when compared to building storage reservoirs.

Recognize that current built infrastructure is often old, may be under-designed and may not be resilient; future maintenance costs may continue to increase.

Post Fire Debris Torrent in British Columbia Omen of the Future?

“Only two things are infinite, the universe and humanstupidity, and I'm not sure about the former.”

Albert Einstein