Water supply concerns of Clallam County due to our changing climate
1) Drinking water supplies
i) East Clallam (based on groundwater aquifers)
Status of physical availability/supply
Aquifers in Sequim-Dungeness are primarily recharged by leakage from streams and
ditches, precipitation, and stormwater runoff, and to a lesser degree from septic
systems, irrigated agriculture, and bedrock aquifers. USGS 1999 has a bar chart
showing the overall water budget for the 3-tier aquifer system. Groundwater
discharges from aquifers to land via well withdrawals and springs, and into the
marine environment below sea level. PGG 2009 indicates a downward trend in
water levels in different aquifers in different areas (confirm amount), most likely
due to increased efficiency in the irrigation system (less leakage) and increased
withdrawals more than climate change to date. Since the early 1990s, residents in
certain areas have found their wells to be too shallow and drilled deeper. The City
of Sequim primary water supply is deep wells; it also utilizes a Ranney collector in
the bed of the Dungeness River.
Legal access
1. Municipal (City of Sequim, PUD, Sunland, largest community systems). Socalled “Group A” water systems have ample water rights for the near future
but fairly soon many will need more and will be required to mitigate impacts
per the 2012 Dungeness Water Rule. Water purveyors may access
mitigation via the Water Exchange or develop their own mitigation plan for
Ecology approval. (Note that the City generates reclaimed water available
for re-use or recharge; this is a potential source of mitigation.)
2. Individual wells and small group (“B”) systems. Most of these users are
exempt from requirements for a water right permit; however, all new users
need to mitigate their impacts (most likely through the Dungeness Water
Exchange). A recent court decision (Swinomish v. Ecology) may affect this
process and/or timeliness.
Potential changes
Expected changes to the local hydrologic cycle include reduced snowpack, earlier
snowmelt, increased winter storm flows, and decreased summer flow. If the annual
volume of aquifer recharge declines, or if changing seasonal patterns of recharge
results in less annual recharge, then aquifer levels will drop. Over the long term,
this will certainly be the case as glaciers disappear and annual snowfields decline in
size and depth. Declining aquifer levels present a direct problem for wells,
especially those tapping the shallow aquifer, and indirect problems for water
suppliers because mitigation for new water rights may become harder to obtain.
The state department of Ecology considers the Dungeness a watershed at risk of
high impact from climate change.
ii) Port Angeles area
Status of physical availability/supply
The Elwha River and Morse Creek, primary sources of supply, are reliable sources at
present except in drought years. Rural residents rely on individual wells and small
group systems, tapping bedrock and shallow alluvial aquifers recharged by
precipitation and river leakage; no supply problems are known at this time (though
it is often difficult to find ample water from bedrock aquifers).
Legal access
1. Municipal (City of PA, PUD, Dry Creek, and others). Suppliers will not be
subject to instream flow regulations unless a water rule is adopted for this
area before they need additional water rights. The adequacy of water rights
to accommodate growth for the foreseeable future should be determined.
2. Small community and individual wells. These are exempt from needing a
water right permit; no mitigation conditions apply (no water rule at this
time).
Potential changes
Same as East Clallam except that the Elwha is a bigger system with more summer
flow stored in glaciers and snowfields. A water rule for the Elwha should probably
be expected after dam removal is complete. Morse Creek may be even more
vulnerable than the Dungeness. Groundwater supplies should be fairly stable for
this area for the foreseeable future, except for wells dependent on leakage from
Elwha reservoirs that are now drained or streams with declining summer flows.
iii) West end
Status of physical availability/supply
Almost everyone uses groundwater in this area, from bedrock or shallow alluvial
aquifers, including the largest purveyor, City of Forks. No supply problems are
known; in some areas it has always been hard to find water. Status should be
determined.
Legal access
1. Municipal supplies with water rights. Adequacy should be determined.
2. Individual and small group wells. These uses are exempt from water right
permitting; no water management rules or mitigation requirements for this
area.
Potential changes
Wells dependent on streamflows for recharge, such as those tapping a shallow
aquifer rather than a deeper confined aquifer, will be vulnerable to declining
summer flows. Bedrock wells with low yields are also vulnerable.
2) Streamflows
a) Fish and wildlife
i) Streams fed in summer by snowfields and glaciers (Dungeness, Elwha, Quileute, Hoh)
Status
Fish and wildlife depend on cold, consistent flows in late spring/early summer in
these systems. Several species of salmon have already been listed as threatened
(see fisheries resources for specific species and stream reaches). In some streams
including the Dungeness, this is at least partly due to low streamflows in summer.
Salmonids are also impacted by higher-than-normal water temperature.
Protection
An instream flow rule was effective at the start of 2013 for the Dungeness and small
streams in the east WRIA 18 watershed, which legally prevents further impacts to
flow from future withdrawals. No other rivers in Clallam County are similarly
protected at this time; however, ESA critical habitat designations provides
protection as well (see fisheries resources for specific species and stream reaches).
Potential changes
Declining glacier/snowfield storage over time will radically change the hydrology of
these rivers. Spring snowmelt volume is expected to decline as snow storage
declines, and the melt is peaking earlier in the summer; baseflows consisting of
groundwater discharge in late summer/early fall will decline if the water table
declines; winter storm flows are expected to become more frequent and therefore
more destructive to in-stream and upland habitat.
ii) Streams with little or no snowmelt source (McDonald, Siebert, Morse, Lee’s, Ennis, Peabody,
Valley, Tumwater, Dry, Salt, Lyre, Twins, Hoko, Sekiu – and other small Strait-draining
streams, plus tributaries to the major rivers)
Status
Fish and wildlife in these systems have evolved with annual precipitation patterns:
periodic high flows in winter and steady baseflows in summer from groundwater
discharge. Streamflow problems for these creeks have generally been connected
with streams with a history of conveying irrigation water (Dungeness watershed).
Protection
Streams in east WRIA 18 (Bagley to Bell) have adopted instream flow protections.
Other north Olympic streams do not have rules drafted. ESA critical habitat
designations provide protection for flow as well (see fisheries resources for specific
species and stream reaches).
Potential changes
East WRIA 18 streams are probably the most vulnerable due to their dependence on
baseflow from an aquifer system that is declining due to changes in land use and
water management. In the case of any stream, if the annual hydrologic budget is
affected by climate change over the long-term (ie., if annual precipitation and/or
storage declines) then groundwater storage and thus baseflows will decline,
affecting fish habitat, especially in summer. This is possible as well if the timing of
precipitation changes radically (ie., shortened wet seasons would cause an earlier
reliance on baseflow).
b) Flooding
Status
Bank overflow is the most likely type of flooding, caused by high flows from storms.
Overland flooding from rapid snowmelt is also common but lowland snow
accumulations may become less common. Where the natural absorbing capacity of a
stream’s floodplain has been reduced, water may flow over the streambank and
damage private and public property. Historically, dikes and levees were installed to
prevent damage; however, storms are expected to increase in severity and frequency.
Protection
Local jurisdictions have Shoreline Master Programs, Critical Areas Ordinances, and other
land use regulations intended to protect public and private property.
Potential changes
Floods are more likely with more severe and/or frequent storms. The “100-year storm
event” (for example) meant a certain precipitation threshold that was exceeded only
every 100 years on average; however, those benchmarks from the past can no longer be
used to predict frequency in the future. Determine whether new benchmarks have been
established for the north Olympic Peninsula.
3) Irrigation supplies for commercial agriculture and hobby farms
i) Dungeness watershed
Status
The vast majority of irrigation in this area is supplied by seven irrigation purveyors
via five diversions that convey Dungeness River water. These entities maintain over
100 miles of irrigation ditches, and are organized as the “Dungeness Water Users
Association” (WUA). Some smaller-quantity water users have diversions on other
streams or use wells to irrigate and/or provide stock water. Some hobby farmers
use wells but most would probably use ditch water if they were able.
Legal access
Irrigation diversions by the members of the WUA have senior water rights obtained
over 100 years ago. The WUA signed an agreement with Ecology in 2012 that
outlines the upper limit of diversion during drought years, including a minimum
streamflow to be maintained. All surface water diversions must have certificated
water rights that pre-date the 2013 Dungeness instream flow rule, because all
streams in east WRIA 18 are now closed to new irrigation withdrawals during the
growing season. Groundwater sources of irrigation without a water right are limited
by the 1945 permit exempt use regulations (RCW 90.44), and since 2013 new
irrigation users must mitigate as described above for drinking water supply (per
WAC 173-518).
Potential changes
Because of their agreement with the State, commercial irrigators face some of the
same challenges as municipal suppliers (see above). Changes to snowpack and the
annual cycle of snowmelt and streamflow will influence water management
decisions among irrigators and other interests.
ii) Outside the Dungeness watershed
Status
Commercial and noncommercial farmers use either surface water diversions or
groundwater from wells.
Legal access
Stream diversions for agriculture are subject to state water law requiring water
rights. Use of a groundwater well is regulated by the 1945 water use regulations.
Wherever instream flow levels are established by rule the ability to get new water
rights in the basin will be more closely regulated (restricted and/or conditioned).
Potential changes
As discussed before, water sources utilized by existing agricultural water users may
be affected by changes to the annual hydrologic budget, i.e., declining snow storage,
declining water table, and changes to the stream hydrograph (earlier and lower
summer peak, more frequent and higher winter peaks). Whether a basin is
regulated or not will determine the ability of the user to adjust their usage to adapt
to changing conditions.
4) Industrial supply
Status
[determine]
Protection
[determine]
Potential changes
[determine]
5)
Indirect impacts
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Fire risk will increase as the hydrology of the forest changes; in turn, wildfire destruction will
speed runoff, increase erosion, and limit infiltration capacity.