4.0 Criteria Used to Determine Stage

The key criteria used to determine the stage of drought response are described in this section. These criteria are listed separately for water systems with surface water sources and groundwater sources. All District water systems are located in a watershed that drains to the Strait of Juan de Fuca. Water systems with surface water sources also differ from one another. The eastern watersheds extend into the Olympic Mountains. Here, the streamflow patterns are driven by both seasonal precipitation and snowpack. The two western water systems are located in watersheds with streamflows primarily driven by seasonal precipitation. The levels of District groundwater sources are correlated to long-term trends in precipitation and snowmelt. Because of this hydrology, District groundwater systems are more resilient to short-term droughts.

The criteria for taking action to conserve or restrict water use apply primarily to the irrigation and early-fall seasons. The District does not own or operate any reservoir facilities capable of storing water for more than a few days of normal use. Conservation earlier than May 1 would not enable storage of surface water in the spring for use later in the season.

Aquifers could be considered a reservoir with seasonal storage capacity; however, District groundwater sources have shown little seasonal variation during droughts when use was not curtailed. Our groundwater sources are much more resilient to drought than our surface water sources.

These criteria are used as guidelines for issuing all drought response alerts. Fire risk and events, precipitation events, updated information on short-term and seasonal weather forecasts, customer comments made in response to District alerts, emergency management agency comments, and other factors deemed critical by the District, will be considered when applying these criteria.

4.1 Criteria for Both Ground and Surface Water Systems

The general criteria for all water systems are the NRCS streamflow forecasts and an emergency drought declaration by the Governor of the State of Washington. NRCS forecasts help in preparing for potential water shortages later in the summer.

NRCS forecasts of drought made in the spring indicate the need to issue a Stage 1 Alert for the District to initiate forecasting using data on local water sources:

• If the February NRCS forecast is 60 percent or less than normal or the Governor declares a drought emergency in March or April, then a Stage 1 alert is immediately issued.
• If the NRCS forecast is 90 percent or less in April, then a Stage 1 alert is immediately issued.
• If the NRCS forecast is 110 percent or less in May, then a Stage 1 alert is immediately issued.

After April, Any emergency drought declaration by the Governor immediately increases the drought response to Stage 2.

Later in the spring, snowpack is used as a criterion for water systems located in the east end of Clallam County. The NRCS operates SNOTEL sites that monitor snowpack in terms of depth (inches) of snow-water-equivalents (SWE). There are three SNOTEL sites in the north Olympic Mountains. The highest elevation site (named Waterhole) is the 6/2018 Drought Response Plan Page 6 of 10 used to determine the date when the snowpack has completely melted (zero depth). See the NRCS website for more information. After a zero SWE is measured at the Waterhole SNOTEL Station, snowmelt runoff begins to decline. This typically happens during mid-June.

The end of snowmelt runoff season will be determined by monitoring daily average streamflow data from Morse Creek, Dungeness River and Hoko River gauges. Monitoring will begin two weeks after the date of zero snowpack. During the snowmelt runoff season, the streamflow will reach a seasonal peak and then decrease at an increasing rate. Later, the streamflow transitions to a recession pattern in which the streamflow decreases at a decreasing rate. The date of this transition marks the end of snowmelt runoff season

The dates of zero snowpacks and the end of snowmelt runoff season are used to determine drought response stages. Earlier dates result in higher stages than later dates.

4.2 Criteria for Only Surface Water Sources

The Fairview and Island View Water Systems have surface water sources. The Fairview Water System is located in a watershed that extends into the Olympic Mountains. The streamflow pattern of the water source is driven by seasonal snowpack and precipitation. The Island View Water System is located in a small watershed in the west end of Clallam County. The streamflow pattern of the water source is driven by seasonal precipitation and not by mountain snowpack.

Fairview Water System

The primary water source for Fairview Water System is Morse Creek. The water right for this source contains a condition to cease diversion when the streamflow drops below 25 cfs. The Washington Department of Ecology (Ecology) operates a streamflow gauge just downstream from the District’s primary point of diversion. Ecology uses the data from this gauge to determine when the diversion must cease.

For the upper Fairview Water System, the 25 cfs limit is the main criteria for determining the drought response stage. The lower Fairview Water System also has three groundwater sources. These sources can fully replace Morse Creek as the primary source during droughts when the Deer Park Road Booster Pump System is operational. Only the upper Fairview Water System is subject to the 25 cfs criterion.

Two weeks after the end of snowmelt runoff season, District Staff will begin estimating the date when Morse Creek streamflow will drop below 25 cfs. One week prior to this date is used as the criterion for preparing the Deer Park Road Booster Pump System for emergency backup operations.

The following table shows the Alert Stage corresponding to the month in which these criteria occur. The highest stage indicated for each month is the stage for which an alert would be issued. All actions of lower stages apply when an alert is issued. For instance, a Stage 2 alert would initiate forecasting actions per Stage 1. A Stage 5 Alert would be issued any time after May, if forecasts indicate that Morse Creek will drop below 25 cfs within a week and the Deer Park Road Booster Pump System is not operational. If the booster pump system is operational and a 1-week forecast in May, June or afterwards, the Stage will be 4, 3 or 2, respectively.

Table 1—Upper Fairview Stage Criteria

Island View Water System

The primary water source for the Island View Water System is Olsen Creek. The water right for this source contains a condition that limits the diversion to one half of the creek streamflow. The maximum diversion is approximately 35 gpm. Per the water right condition, the diversion must be reduced when streamflow drops below 70 gpm (0.156 cfs).

Olsen Creek streamflow is estimated from the Hoko River. There is no streamflow gauge on Olsen Creek. The closest river with a long-term gauge is the Hoko River. The gauge is operated by the U.S. Geological Survey (USGS). The Hoko River daily average streamflow data is multiplied by factor derived from the ratio of watershed areas of the creek and the river. The watershed area of Hoko River upstream from the gauge is 51.2 square miles. The watershed area of Olsen Creek upstream of the diversion is 0.93 square miles. The adjustment factor is 0.00539, which is the watershed area ratio raised to the 1.3 power.

The District will begin forecasting Olsen Creek streamflow when the Hoko River falls below minimum monthly level observed during the spring. These levels will be determined by July 1st. The District will forecast the date when the estimated Olsen Creek streamflow drops below 0.077 cfs. This corresponds to a Hoko River streamflow of about 14.3 cfs.

The following table shows the Alert Stage corresponding to the month in which these criteria occur. The highest stage indicated for each month is the stage for which an alert would be issued. All actions of lower stages apply when an alert is issued. For instance, a Stage 2 alert would initiate forecasting actions per Stage 1.

Table 2—Island View Stage Criteria

Gales Addition, Monroe & Mount Angeles Water Systems

The water source for these three water systems is the Elwha River. The City of Port Angeles delivers treated Elwha River water to the Gales Addition Reservoir, which serves all three water systems. The District will issue the same drought alerts as the City of Port Angeles.

4.3 Criteria for Only Groundwater Sources

Table 3—Depth to Groundwater for Stages 2 - 5

For the water systems with only groundwater sources, except Clallam Bay/Sekiu, routine District well monitoring data will be reviewed after the end of snowmelt runoff season on Morse Creek. The review will compare the routine depth to groundwater measurements with the average of historical measurements. A drought alert will be issued based on the depth to groundwater above the highest screened interval. The depths in the table represent 20, 40, 60 and 80 percent of the normal depth of groundwater above the highest screened interval for Stages 2 through 4, respectively.

The Hoko River Wellfield is the source of water for the Clallam Bay/Sekiu Water System. There is no well level monitoring system for this wellfield. The Hoko Pump Station uses a vacuum system to pull water from the wells to prime the pumps. The vacuum is monitored and is an indirect measurement of the depth to water in the wells. There has been no seasonal variation in vacuum observed. This indicates that the groundwater source is resilient to droughts.

In the absence of direct well level monitoring, the criteria used for Clallam Bay/Sekiu is Hoko River streamflow. Because of the greater of resiliency groundwater sources to drought, these criteria are less stringent than for a surface water source. The following table shows the Alert Stage corresponding to the month in which these criteria occur. The highest stage indicated for each month is the stage for which an alert would be issued. All actions of lower stages apply when an alert is issued. For instance, a Stage 2 alert would initiate forecasting actions per Stage 1.

Table 4—Clallam Bay/Sekiu Criteria