What is an Augmentation Plan and What Is Its Value?

Augmentation plans in Colorado were established in the 1969 Water Rights Determination and Administration Act (“1969 Act”). The 1969 Act recognized the hydraulic interaction relationship between surface water rights and alluvial groundwater rights, and that groundwater rights that were generally junior to surface water rights could injure the senior rights, especially since at the time there was rapidly increasing alluvial well pumping. Therefore, one of the results of the 1969 Act was to require augmentation plans for junior water users on over-appropriated streams that would require these users to obtain sufficient replacement water to offset any injurious depletions to senior water rights. In this way, junior water rights could continue to pump as long as they didn’t injure the senior rights. Augmentation plans apply to junior alluvial aquifer groundwater rights adjacent to a stream, as well as not-nontributary water of the Denver Basin.

The statutory definition of a plan for augmentation is to “increase the supply of water available for beneficial use in a division or portion thereof by the development of new or alternate means or points of diversion, by a pooling of water resources, by water exchange projects, by providing substitute supplies of water, by the development of new sources of water, or by any other appropriate means.” However, plans for augmentation cannot include the salvage of tributary waters by the eradication of phreatophytes (Southeastern Colorado Water Conservancy District v. Shelton Farms, Inc), nor does it include the use of tributary water collected from land surfaces that have been made impermeable, thereby increasing the runoff but not adding to the existing supply of tributary water.

What is an augmentation plan?

The 1969 Act provides the means to administer surface and groundwater rights concurrently and provides that augmentation plans will mitigate material injury to senior water rights. Surface water users divert directly from a stream using a headgate and administration of surface water rights is relatively straightforward, as the headgate of a surface water right can simply be closed if the right is out of priority. However, it is more complicated for tributary groundwater rights, as shutting down a well does not stop ongoing depletions to the river, thus there can be ongoing injury to senior surface water rights even after a groundwater well has stopped pumping. This is known as lagged depletions, i.e., pumping a well creates a cone of depression that can extend to a stream and, by virtue of a hydraulic gradient from the stream to the well, extract some water from the stream that is then produced from the well. This process is acceptable as long as the junior groundwater well is in priority. However, if a call places this well out of priority, shutting down the well does not immediately dissipate the cone of depression of the well. As such, depletions from the stream can continue even after the well has been shut down. An augmentation plan is designed to “augment” the flow in the stream to what it would have been if the junior groundwater well had not been pumping and depleting the stream only on days when its depletions were out of priority.

To obtain an augmentation plan, an application needs to be made to the Water Court. The essential elements of an augmentation plan are the (a) source of water that will be augmented, (b) the augmentation source, (c) the hydraulic relationship of the pumping of the source of groundwater and the adjacent stream using the Glover equation to estimate lagged depletions, and (d) a showing that the augmentation source is both reliable to offset out-of-priority depletions and is sufficient in terms of quantity and quality to serve as a replacement water supply to prevent injury to senior water rights.

An augmentation plan, once adjudicated, allows a junior appropriator of tributary, or not-nontributary, groundwater to continue to pump as long as the appropriator replaces injurious depletions to senior water rights. For example, municipal water suppliers may have a tributary groundwater well field that can continue to operate based on the release of reusable effluent from its water reclamation facility, thereby augmenting the stream in an amount equal to, or greater than, the lagged depletions from the tributary, or not-nontributary, pumping. Not only does this provide an acceptable augmentation plan, it is also a form of indirect potable reuse that optimizes the beneficial use of water.

What are augmentation plans used for?

One of the principal uses for augmentation plans is to augment lagged depletions from tributary alluvial wells or not-nontributary wells, as described in the example above. Another use for augmentation plans is to mitigate depletions from the dewatering of shallow alluvial aquifers, as building and construction in these settings may require dewatering systems to obtain stable subsurface conditions for foundation installation. Dewatering is also typically necessary related to mining activities, as ore bodies have to be dewatered to allow both surface and underground mining operations to proceed safely. Any dewatering that causes depletions to groundwater requires either a Substitute Water Supply Plan for temporary dewatering, or an augmentation plan for permanent dewatering operations.

Augmentation plans can also be required where water is potentially stored out of priority and alternate equivalent volumes of water must be released to the stream. Augmentation plans may also be required in alluvial aquifer storage and recovery (“ASR”) projects to demonstrate no injury to existing users and/or no degradation in water quality. With the passage of Senate Bill 5, which became effective on January 1, 1986, some of the Denver Basin aquifer water supplies are considered to be not-nontributary, which also requires that an augmentation plan be adjudicated prior to the use of the not-nontributary water so both pumping period and post-pumping period depletions are adequately replaced through the plan.

There are a number of possible sources for augmentation water for any of the uses described above, including:

·         Senior water rights changed to augmentation use

·         Junior storage rights that are stored in priority

·         Reusable water reclamation effluent

·         Nontributary water

·         Lawn irrigation return flow (LIRFs)

Augmentation plans provide a very useful tool in allowing the use of junior tributary rights where they would otherwise not be able to operate. This results in an increase in the overall beneficial use of water, as in-priority diversions of junior water rights do not have to be augmented, only those depletions that occur from the groundwater pumping when the junior right would otherwise be out of priority have to be augmented. Augmentation plans, in combination with exchanges, help water suppliers provide a more efficient water supply system.

How can LWS help?

LWS can provide a full suite of technical services related to augmentation plans and water rights in general. LWS has developed numerous augmentation plans for municipal water supply entities, mining clients, and developers so either new, or more efficient, water supply systems could be developed. A key factor in all augmentation plan applications is an injury assessment to demonstrate that the source(s) of water to be augmented can be fully covered by the source(s) of augmentation such that no material injury will occur to senior water rights. To do an injury assessment it is necessary to evaluate the timing, amount, and location of depletions from the groundwater source. That information is then compared to the physical and legal availability of the augmentation source(s) to demonstrate that the augmentation source is reliable to replace all anticipated out-of-priority depletions. After the adjudication of the augmentation plan, LWS can also provide the necessary accounting services, including tracking tributary pumping, daily call data to determine if the right is in or out of priority, augmentation requirements to replace out-of-priority depletions, and balancing of accounts to demonstrate compliance with the plan.

For more information, please give Lytle Water Solutions a call.

Phone: 303-350-4090

Email: Bruce Lytle bruce@lytlewater.com , Chris Fehn chris@lytlewater.com , or Anna Elgqvist anna@lytlewater.com