Sensitive Resource


Use the archive archive below to learn more about news, impacts and issues regarding the possible redesignation of the LPRV aquifer to sensitive aquifer status. Select a topic from the list below and then CLICK to access.


Quick Facts


Minutes: June 20, 2000
Minutes: June 23, 2000


Draft Final Report, 06/20/01
Download Full Report (PDF)

Phase I Progress, 01/04/01
Browse Full Report


Physical Hydrology
Water Quality Impacts
Highway Pond
Sensitive Resource
Browse Full Presentation


Aquifer Schematic
Aquifer Water Balance
Aquifer Watershed
Contamination Sources
Groundwater Use: 1950-2000
Highway Pond
Pocatello Water Service Areas
Preliminary Vulnerability
TCE Plume Location
Underground Storage Tanks
Water Use Cycle

You can also learn more
about the LPRV aquifer
Aquifer Protection!

Some archive entries are
in Power Point,
others are in PDF format.

LPRV AQUIFER: A SENSITIVE RESOURCE CLICK for a full-sized Preliminary Vulnerability Map!

The Lower Portneuf River Valley Aquifer (LPRV) is a fast moving, fairly shallow aquifer with a limited amount of soil cover over gravels. The aquifer has been described as vulnerable through the source water assessment process (see Hot Water Topics) in addition to many geological studies. Past practices have included activities that have impaired and have the potential to impair the aquifer.

The gradual deterioration in water quality which has been occurring over the last 15 to 30 years (see chloride trends and nitrate trends) and more recently (see TCE plume and leaking underground tanks) provide ample evidence that the aquifer is being impacted by pollution originating at or near the land surface. If the sources of these contaminants (such as septic systems, storm water runoff and hazardous materials/fuels) are not controlled, the rate of water quality degradation will likely accelerate and/or other, serious pollution threats will develop that will have to be dealt with through remediation.

The lower Portneuf Valley aquifer is vulnerable because of several factors:

1) Varied urban, residential, industrial, and agricultural land uses with the potential to contaminate the water supply occur directly over the aquifer.

2) Water and contaminants originating at the surface can move quickly to the water table because the aquifer has minimal natural protection (thin soil cover, shallow water table, highly permeable Bonneville gravels between the surface and water table). GO VISIT the hydrology section of the Digital Atlas of Idaho 2000 to learn more about the Bonneville Flood.

3) Numerous artificial sources of recharge associated with urban/residential land uses (drain wells, ditches, septic leach fields) accelerate the movement of contaminants to the water table.

4) The highly permeable aquifer spreads contaminants rapidly, making it difficult to clean up contamination once it has entered the aquifer.

In addition, the lower Portneuf Valley aquifer and its immediate tributary aquifers comprise the effective sole drinking water source for Pocatello, Chubbuck, and northern Bannock County.

All of these factors also exist in the Rathdrum Prairie aquifer, where for the past 20 years, proactive management approaches have been developed to provide enhanced groundwater protection against contaminant threats related to urban, residential, and commercial development. These management approaches were implemented because the same kinds of trends in water quality that the lower Portneuf aquifer is experiencing were documented in the Rathdrum aquifer and future water quality was projected to degrade with continued development.

For these reasons, the agreements and management methods that were developed and adopted by communities and jurisdictions on the Rathdrum Prairie aquifer comprise a valuable template for other Idaho communities, such as ours, considering enhanced ways to improve groundwater protection.

Through efforts of the Panhandle Health District, Idaho Department of Environmental Quality, the Environmental Protection Agency, and state and congressional appropriations, the Rathdrum Prairie aquifer was designated in 1980 as a Special Resource Water under state Water Quality Standards and Wastewater Treatment Standards. Through this designation, citizens and officials have worked to develop and adopt an integrated protection program. Because of its status, the Rathdrum Prairie aquifer became the only aquifer in Idaho to be classified in the Sensitive Resource category when the state groundwater Quality Rule (GWQ Rule) was promulgated.

Under the GWQ Rule, by default all Idaho aquifers are classified in the General Resource category. Only through a petition to DEQ can an aquifer be reclassified from the General category into the more stringent Sensitive Resource category or into the less strict Other Resource category. In principal, the intent of recategorization is to achieve a level of protection which is best suited to the identified beneficial uses which an aquifer is deemed to provide. To achieve the Sensitive Resource designation, for example, more strict numeric water quality standards (lower allowable concentration limits) and / or narrative standards (water quality goals and protection intent) are established, with which to maintain or improve existing water quality, using a combination of best management methods and best available management practices.

The advantages to recategorization to a Sensitive Resource as a means of achieving protection is that it enables a jurisdiction or a collective to identify:

a) what type of groundwater protection is needed and feasible for their site-specific hydrologic, economic, and resource management conditions;

b) cooperatively develop management tools to achieve that level of protection; and

c) to implement and enforce those tools uniformly across an agreed management area. for the long-term.

Although a state-sanctioned mechanism such as Sensitive Resource reclassification is not necessary to achieve protection, a less formal agreement among local jurisdictions may make it more difficult to ensure both long-term and uniform enforcement of the necessary protective regulations across the management area and beyond changes in political leadership.

The principal drawbacks to recategorization are economic and hence political. For example, it will cost more to control sewage impacts from homes built outside city limits (by requiring connection to municipal sewer services or installation of enhanced sewage treatment systems, or requiring fuel storage facilities to build enhanced containment systems (e.g. double-walled tanks, lined fuel containment structures). Although such measures will provide long-term benefits by reducing future remediation costs for groundwater contamination, assigning economic value to such future benefits is difficult.

Ultimately, the decision whether or not to adopt stricter protective measures will be a community-wide responsibility, wherein water managers, citizens, and political leaders will need to work together to decide what action if any will be taken. In the lower Portneuf Valley, where limited future water capacity and development planning needs are already focused on the community's future water supply, tying aquifer protection to the Our Valley, Our Vision buildout planning efforts is a logical step to ensure that all sectors of the community will have a say in defining future needs and the means of achieving shared community goals.

Currently, a number of conditions have come together to assist Idaho communities in general, and this community in particular, to achieve aquifer protection if they so decide. In order to answer the most pressing questions from political leaders and representatives of local commerce and industry on the economic implications of aquifer protection, a special legislative appropriation was obtained by Representative Roger Chase to fund an Economic Impact Analysis (see archive at left), of the projected costs and benefits of adopting enhanced protection measures compared to not adopting such measures. The results of this study, the first phase of which was completed in May, 2001, provide important information on which all sectors of the community can base decisions as to how to proceed.

In addition, individuals are encouraged to participate in monthly meetings of the Portneuf groundwater Forum, a technical and policy advisory group, and to join our group - the Portneuf Valley Groundwater Guardian committee.

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