WRIA 1: Water Resource Inventory Area No. 1, Water Management Project

1. About the Watershed
2. Water Quantity

ABOUT THE WATERSHED

Water Quantity

The overarching Water Quantity goal stated in the March 2000 WRIA 1 scope of work is:

To assess water supply and use, and to develop strategies to meet current and future needs.  The strategies should retain or provide adequate amounts of water to protect and restore fish habitat, provide water for future out-of-stream uses, and to ensure that adequate water supplies are available for agriculture, energy production, and population and economic growth under the requirements of the state’s Growth Management Act (GMA).

To meet this goal, technical assessments were conducted to assist WRIA 1 participants to understand the nature and extent of water quantity issues and to develop technical tools to help address the issues identified.  The March 2000 Scope of Work identified the following specific technical assessment requirements, many of which are required by Chapter 90.82 RCW:

• Estimate the amount of surface and groundwater present;
• Estimate the total amount of water available in an undepleted condition;
• Estimate the amount of surface and groundwater actually being used in the WRIA;
• Conduct a depletion analysis to accurately estimate the spatial and temporal uses of water in the WRIA throughout the year;
• Estimate future water needs;
• Estimate the amount of water represented by claims in the water rights claims registry, water use permits, certificated rights, existing minimum instream flow rules, federally reserved rights, and any other rights to water (1); Use the best available science to make reliable estimates of the Lummi Nation water rights for both instream and out-of-stream uses;
• Identify the most senior instream and out-of-stream water rights in the WRIA and the next most senior rights in turn based on the priority date of existing water right holders;
• Estimate the amount of surface and ground water available to junior users and for further appropriation taking into account seasonal and other variations and the minimum instream flows adopted by rule or to be adopted by rule under the RCW for streams in the management area including the data necessary to evaluate necessary flows for fish.
• Identify location of areas where aquifers are known to recharge surface bodies of water and areas known to provide for the recharge of aquifers from the surface;
• Contract with USGS to collect streamflow data throughout the watershed for the multi-year [10 year] effort;
• Measure and/or estimate climate data (precipitation, evapotranspiration) at representative locations in the WRIA;
• Evaluate existing land use/land cover data for its suitability in making water resource related decisions.

These requirements were used along with local perspectives to identify the approach and actions to be implemented for the water quantity technical assessment work.

The overall approach used to evaluate how much water is present and ultimately available for current and future use required assessing two fundamental types of information:

1. The physical factors influencing when, where, and how much water can be found in WRIA 1; and
2. The legal constraints and considerations that identify how much water has been legally obligated, to whom, and when, including unresolved water rights.

The physical factors include the amount of rainfall and when and where it occurs, the amount of water used and/or committed, the type of land cover, streamflow, groundwater recharge, and the connection between groundwater and streamflow (hydraulic continuity).  These factors are components of a water balance and are illustrated in the figure below.  A water balance and associated models are being constructed as part of the technical assessment work for water quantity.

Inherent to use of a water balance, is the recognition that the amount of water present and available is not a static number but changes over time and space as those factors previously noted (e.g., precipitation, use) change.  The models being developed will enable these changing factors to be considered and will enable different management actions to be evaluated for their effectiveness.  Such management actions include:

• Changes in the amount of water used including changes in the location and timing of water use (e.g., changing surface water use to ground water use and vice versa, changing the timing and location of groundwater use; changing the rate of water use including e.g., adjusting irrigation efficiency and other conservation measures);
• Changes in land use and cover;
• Changes in climatic factors such as precipitation and temperature;
• Evaluating possible storage options; and
• Evaluating transfer of water between drainages.

Legal constraints and considerations fall under water rights/water law.  Among other things, these laws determine who can use water, how much, when, where, and for what purpose.  These laws can be divided into two general types:  1) State Water Rights, which are applicable to water use on State lands, including State agencies and private property owners and residents; and 2) Federally Reserved Rights, which pertain to lands set aside out of the public domain for a specific federal purpose, such as an Indian reservation, National Park or National Forest. 

Information in both these areas (physical and legal) is essential to understanding how much water is present and what may be available to meet existing and future needs in WRIA 1.  USGS and USU were the entities that conducted the majority of the work associated with understanding the physical factors for the WRIA 1 Watershed Management Project.  PUD No. 1 contract staff and WRIA 1 Project participants have conducted most of the work associated with the water rights/water law information.  In the following discussion, the USGS and USU work is discussed first followed by an overview of work associated with water rights/water law.