Hayden Lake located in Kootenai County, Idaho is the county’s third largest lake. The Hayden Lake watershed is predominantly forested with sixty-three percent of the watershed in the management of the U.S. Forest Service. Additional forest land is in private ownership. The lake drains by subterranean seepage to the Rathdrum Prairie Aquifer.

The lake has undergone shoreline development in some manner or another since the 1880s. The lake was impounded by a dike in 1910 increasing the lake’s size and altering its previous annual rhythm of drainage. Development extends around the lake with roughly half of its northern, eastern and south eastern shoreline characterized by a single strip of cabins or homes. Most cabins remain summer retreats while an increasing number are becoming year around residences. The more heavily populated south, western and northwestern shores have sewer service from the far side of Sandy Bay to Cramps Bay. Remaining habitations use septic treatment with drain fields required to be set back from the lake.

Water quality issues have arisen concerning the lake since the 1950s. These were primarily concerned with septage drain fields in too close proximity to the lake. Over time, the county rules addressed these issues. Around 1985, forest harvest planned by the U.S. Forest Service in Yellowbanks Creek, the lake’s second largest tributary, caused concern by lakefront owners and lake users. Concern led to the development of a citizens’ interest group, Save Hayden Lake. The group found funds to sponsor an in- depth study of the lake water quality and the loading of plant growth supporting nutrients to the lake. The study was conducted by Eastern Washington University’s limnologist, Dr. Ray Saltero (Saltero et al. 1986). Shortly after the study, two unrelated events led to the development of a management plan for Hayden Lake.

The Idaho Legislature passed the Clean Lake Coordinating Bill (Chapter 64 Title 39 Idaho Code; Repealed HB 450 2010) in the late 1980s. The legislation authorized the Panhandle Health District (PHD) to create management plans for all the lakes of North Idaho. The Health District set up a council to coordinate the work and began the planning effort. Owing to both the public interest to protect Hayden Lake, and the basic scientific groundwork completed by Saltero, Hayden Lake received quick attention. By 1994, the original Hayden Lake Management Plan was in place (PHD 1994). Unfortunately, the plan based on Saltero’s baseline work was strong on goals and objectives, but rather weak on how those objectives would be achieved. Among those goals was a total phosphorous goal for the lake of 7.0 micrograms per liter in the lake’s water. Lakes with total phosphorous concentration under 15 micrograms per liter are, by definition, classified as oligotrophic or clear with low nutrients and low productivity. Saltero’s work found the main lake total phosphorous to average 7.5 micrograms per liter, but that portion of the lake north of Henry’s Point was found to be very eutrophic with total phosphorous in excess of 25 micrograms per liter. This condition was subsequently found to be the result of the shallow nature of the lake in this area which is artificially inundated throughout the summer due to the presence of the Hayden Lake Dike. Why the work group that developed the original plan chose a mid-lake total phosphorous goal of 7 micrograms per liter is unknown. No rationale exists in the plan.

In a completely different effort at the federal level, Congress reauthorized the Clean Water Act of 1972 in 1987. The reauthorization bolstered management of the nonpoint side of surface water contamination. Added sections required the states to assess all their surface waters for attainment of beneficial uses and to ultimately prepare a list of water quality limited segments. Idaho completed its initial assessment in 1989. Since the state was required to report based on any assessment, many initial assessments were windshield surveys at best, especially for more remote streams. Where data existed like that developed for Hayden Lake, the task was more scientifically grounded. Since the measured average for total phosphorous by Saltero and later from citizen’s volunteer monitoring by Black, was 7.5 micrograms per liter and the lake plan goal was 7 ug/L, Hayden Lake was listed as water quality limited. All water quality limited water bodies required additional assessment. If assessment found the water body limited, a total maximum daily load (TMDL) was required.

Hayden Lake was further assessed in an analysis addressing all the listed water bodies of HUC (Hydrologic Unit Code) 3050200. Since the goal was set at seven and the continuing monitoring found the total phosphorous concentration at seven and a half micrograms per liter, the assessment found Hayden Lake water quality limited. A TMDL was prepared that prescribed the phosphorous load reduction necessary to attain the 1994 management plans total phosphorus goal of 7 micrograms per liter (DEQ 2001). The TMDL prescribed a 709 kilograms per year phosphorous load reduction.

After the TMDL was in place, the Department of Environmental Quality gathered a working group of the lake’s stakeholders to develop a TMDL implementation plan. The group met a few times, but eventually dissolved with its only product a resolution to begin a lake protective association. From this resolution the Hayden Lake Watershed Association came into existence. The Association was not the only citizen group operating on behalf of the lake and its watershed. Save Hayden Lake had re-emerged primarily to oppose the expansion of Camp Mivoden’s physical facilities. After Kootenai County granted the camp’s permit to expand based on specific conditions, Save Hayden Lake and the Watershed Association merged to form the Hayden Lake Watershed Association Inc. The larger Association took on several issues in the protection of the lake and its watershed. Among these was completion of a TMDL implementation plan. The Association chose to create an addendum to the Hayden Lake Management Plan which contained specific phosphorous load reducing projects. The addendum was completed in 2009 (HLWA 2009).

Since the Hayden Lake Management Plan Addendum was finalized, the Association has consistently worked to have specific projects implemented. During the intervening thirteen years, several projects have been successfully completed. Additionally, some cultural practices have ceased or have been in abeyance. Specifically, the two cattle grazing operations in the watershed have ended and the Forest Service has not harvested timber in over twenty-five years.

Given the extended period since the TMDL implementation plan was put in place, it is time to review the plan and the effectiveness of the projects it delineated in lowering the total phosphorous concentration of the lake.

The management plan addendum contained projects or investigations grouped under six categories. These were: Wastewater Assessment and Treatment Projects, Storm Water Capture and Treatment, Forest Service Projects, Agriculture Projects, Public Road Projects, and Emergent Aquatic Vegetation Management. The projects listed under any one of these categories were listed by priority. The priority was most often based on the amount of phosphorus reduction expected.

The goal of the plan was to reduce the total phosphorous loading to the lake by nearly 712 kilograms per year. Algal growth in the lake main body of Hayden Lake is limited by phosphorous concentration. The phosphorous chemical compound absorbed to drive the growth of algae is orthophosphate. Unfortunately, orthophosphate at the concentration of total phosphorous in Hayden Lake is typically at, or just below, the chemical detection limit. For this reason, total rather than ortho-phosphorous is used as a more reliable measure. This is scientifically reasonable because there exists a strict relationship between total and ortho-phosphorous concentrations. A constant and small amount of ortho- phosphorous is chemically dissociated from the larger total phosphorous pool at the temperature, and pH of Hayden Lake. Thus, as the total phosphorous concentration rises so does the proportionately much smaller ortho-phosphorous concentration. Simultaneous measures of total and ortho-phosphorous prove this relationship and are reflected in the lake monitoring data. The 712 kg per year reduction goal is the reduction that would, theoretically, lower the average mid-lake total phosphorous to 7 ug/L, the management plan’s concentration objective.

See Below

The wastewater assessment and treatment projects were in order of priority: 1) Mivoden community wastewater treatment system upgrade to non-phosphorous contributing land application system, 2) identify and create local solutions for failing on-site wastewater treatment systems, and 3) identify and hook up failing on-site wastewater treatment systems (Table 1).

Table 1: Wastewater Assessment and Treatment Projects

The Mivoden community system upgrade was a condition of the Kootenai County permit allowing expansion. Implementation of the project was well underway when the addendum was developed and was completed shortly thereafter. The termination of Mivoden’s septic drain field located quite near the lake and the establishment of a treatment and land application system located nearly a mile from the lake essentially ended this contribution to the lake. An estimated 137 kilogram phosphorous per year was removed from the load reaching the lake.

The Panhandle Health District conducted an assessment of septic treatment and drain field systems around the lake shortly after the addendum was in place. An exceedingly small number of problems systems were discovered. Those few exclusive to the Hayden Lake Sewer District’s collection system were required to modify their systems to solve any discharge issue primarily by removing drain field further back from the lake. Those few failing systems discovered in the sewer district’s collection area were required to hook up to the sewer. These removals were so minor their contribution to phosphorous reduction is not estimated.

The last septic survey was conducted over ten years ago and drain fields can fail with time, especially if their use increases. Given the elapse time and the fact that some vacation homes have been converted to permanent residences, a new survey by PHD is in order.

Storm water discharge and the sediment and attached phosphorous it carries was a concern when the original Hayden Lake Management Plan was developed. Phosphorous yield modeling developed by Panhandle Health District with the assistance of the University of Idaho indicated that storm water runoff from the lake’s heavily-developed south shore between the dike and the Hayden Lake Marina was of major concern. When the addendum was developed the modeling was repeated with updated modeling methods. The result predicted the second largest phosphorous yield was from the south shore storm water. For this reason, a pilot surface water capture and treatment project was designed to test a modular treatment system and subgrade discharge was scheduled (Table 2). If the system succeeded. A scaled-up project was envisioned to remove additional phosphorous.

Table 2: Storm Water Capture and Treatment Projects

Before undertaking expensive capture and treatment of stormwater abatement projects, the Hayden Lake Watershed Improvement District sought an independent assessment of the previous modeling. A monitoring program was designed to measure storm water discharge and test its phosphorous concentration. Six small watersheds were identified on the slope above the south shore. Each was monitored during runoff events for discharge and phosphorous concentration. From these data the loading of phosphorous to the lake from stormwater was calculated. The monitoring data resulted in yields that were far below those estimated by the modeling. The measured phosphorous loading was so low that any storm water retention and treatment would not be cost effective. Based on this analysis, the Hayden Lake Watershed Improvement District decided it was not worthwhile to address storm water. An open question remains on the fate of phosphorous known to be deposited from the atmosphere between its deposition point and the lake.

The Forest Service projects were in order of priority: 1) culvert replacement on the Ohio Match Road (FSR 206), 2) Stump – Shamrock Meadow Restoration, 3) FSR 437 (lower) upgrade, 4) N F Hayden Creek Road decommissioning, 5) complete headwater Yellowbanks and Jim Creek haul road decommissioning, 6) E.F. Hayden Creek Road (FSR 437) encroachment upgrades, 7) hardening of EF Hayden Creek crossing at Hells Canyon Trail, and 8) Lancaster Creek culvert restoration at FSR 206 crossing (Table 3).

Table 3: Forest road and floodplain restoration projects, Hayden Lake Watershed.

1 Activities stabilizing and restoring roads to a more natural state. These activities include removal of stream crossings and full re-contour of the road prism, introduction of woody debris and re-vegetation as needed.

The Forest Service replaced all but one of the old wooden box culverts on the Ohio Match Grade (FSR 206). Since the culverts did not fail before replacement, it is likely little phosphorous load was addressed, but the potential for very large loads persisting over many years was averted. Mud bogging in both Stump and Shamrock Meadows was stopped through a combined effort Association to procure logs and Forest Service placing them to discourage the activity and more strict enforcement efforts by the Forest Service. The lower Hayden Creek Road between the forest boundary and the shooting range remains a primary sediment and therefore, a phosphorous source. Efforts are underway to address this road which is located so that sediment drains directly to Hayden Creek only a mile or two before it enters the lake. A part of the problem is the unregulated shooting range that itself drains to Hayden Creek. None of these efforts have, to date, stopped the sediment and phosphorous export to the lake. Although the North Fork Hayden Creek Road was closed to all but administrative use by court order, the areas of this road’s encroachment on the North Fork Hayden Creek have never been addressed and the road has not been decommissioned. The decommissioning of haul roads was completed in the Yellowbanks and Jim Creek watersheds. The encroachments of the East Fork Road (FSR 437) have not been addressed, however a plan the Association suggested to the Forest Service does address these. Hopefully, these improvements and those on the North Fork Road will be made as part of the Honey Badger Project. These roads will be major haul roads for the timber sales planned. The open water crossing of single-track motorcycles onto the Hells Canyon Trail has not been hardened. However, the old Hells Canyon Trail that followed the stream in locations very closely was replaced with a new trail located on the south facing side hill. No phosphorous reduction estimates have been ventured for the trail replacement, but the relocation certainly decreased sediment and therefore, phosphorous export to the East Fork Hayden Creek. Replacement of the culvert conducting Lancaster Creek under Ohio Match Road (FSR 206) occurred roughly twelve years ago. The two rusted out eight-inch culverts were replaced with a single thirty-six inch culvert. The replacement culvert does retard fish passage, but this may not be an issue this high in Lancaster Creek.

Estimating the phosphorous reduction from the Forest Service Area Projects is difficult. The highest priority project was preemptory rather than corrective. Its phosphorous reduction cannot be tallied. However, the cessation of mud bogging in Stump and Shamrock meadows, Jim and Yellowbanks haul road decommissioning and Lancaster Creek culvert replacement were achieved as was the relocation of the Hells Canyon Trail. In addition, the Forest Service has not harvested timber in the Hayden Creek watershed for over twenty-five years. This cessation surely allowed many sediment sources to heal while others were not created. A net decrease of 15 to 23 kilograms per year is not unreasonable.

The greatest progress now can be made by decommissioning FSR 437 between the forest boundary and the lower Ohio Match Road (FSR 206) junction. If a replacement for this road is desired the Association has proposed a replacement on primarily existing road grades on the southern flank of Hudlow Mountain. Although the Honey Badger Project will usher in a new round of forest harvest in the watershed managed by the Forest Service, it also provides an opportunity to address issues on both the upper FSR 437 and North Fork Hayden Creek Roads, and the hardening of the Hells Canyon Crossing.

The roads projects were listed by the then supervisor of the Lakes Highway District working closely with the Association. The projects included 1) continuing ditch maintenance of Upper East Hayden Lake Road and East Hayden Lake Road which circles most of the lake, 2) creation of storm water retention ponds during curve reconstruction on Lancaster Road, 3) paving of Mokins Bay Road, and 4) survey of drainage from private roads (Table 5).

The first three projects were implemented with the first remaining an ongoing effort. The highway district continues to remove sediment deposited in it inside ditches to a soil repository out of the watershed. Such maintenance is a required practice to maintain the road grades. The curve on Lancaster Road just beyond English Point was rebuilt nearly ten years ago with the settling ponds placed. Mokins Bay Road (mis- identified as Nilsen Creek Road) was paved two years ago. Conservatively, completion of these projects removed 64 kilograms per year.

Although no direct assessment was ever made of discharge from private roads, the storm water monitoring completed by the Watershed Improvement District addressed this issue at least in part for the Upper and Lower East Hayden Lake Roads between the dike and the Hayden Lake Marina. Certainly, private roadway development continues with land development. In some cases, these roads are well constructed and erosion mitigation is installed, while in others the opposite has been the case. Typically,a failure uphill of the county road ends up in the road ditch where the highway district deals with it. This cannot be said for poorly constructed and protected roads downhill of the Highway District’s roads.

Table 5: Lakes Highway District projects designed to abate erosion.

Agriculture in the Hayden Lake Watershed was limited to a very few tributary watersheds, Lancaster, Nilsen, Stump and Bervin Creeks. Most of the agriculture involved animal husbandry with some hay

Table 4: Agriculture stabilization projects, Hayden Lake Watershed

• based on 5% delivery to surface

production. The Kootenai-Shoshone Soil Conservation Commission staff developed a plan to address the water pollution issues that existed (Table 4).

The Commission’s staff worked with landowners to implement fencing projects in Nilsen and Lancaster Creeks. Some of the problems sites in the Stump Creek watershed were addressed by the acquisition of the property by Fish & Game with Northwest Power Plan mitigation funds. After the acquisition, grazing in this area was ended. Some horse grazing may remain on Bervin and Nilsen Creeks. The running of horses on properties comes and goes with owners. The implemented projects are estimated to have reduced phosphorous yield by some 16 kilograms per year.

Another change not envisioned in the plan occurred in the watershed. There were two grazing operations in the watershed and a third that overlapped partially. One was centered in Lancaster Creek. The operation was confined to the owner’s property along the creek and possibly some adjacent private forest land. The second range stretched along the east shore from as far north as Stump Creek to as far south as Yellowbanks Creek. Since the area was state-recognized open range, it was the private owner’s responsibility to fence out the cattle. The third operation was located west of the watershed on private and state-owned property, but did range into Upper Lancaster, Cherry and lower Hayden Creeks acreage managed by the Forest Service. This operation was the first to end when its owner gave up the business. The Fish and Game acquisition of the Stump Creek headwaters and fencing, ceased impacts from this herd on the watershed. Eventually the owner of the operation along the east shore became elderly and essentially lost control of this herd. Eventually the herd waned out of existence. The cattle operation in lower Lancaster Creek is in the process of shutting down. The meadows grazed appear to have lighter usage than in earlier years. There is rumor that that the land will be subdivided and sold for home development. The impact of this cattle grazing on streams and the resultant phosphorous yield to the lake was never estimated. Nevertheless, there was a phosphorous yield associated with the grazing operations impact on the tributaries that has ceased since the implementation plan was put in place.

The cycling of phosphorous from the bottom sediments into the water column by emergent aquatic vegetation was poorly understood when the plan was developed. At that time Eurasian milfoil was the only emergent aquatic of concern. Since that time, curly leaf pondweed has become invasive problems in the lake.

The projects envisioned to address invasives were 1) Assessment of phosphorous cycling potential of aquatic emergent, 2) assess the best control methods, and 3) control Eurasian milfoil (Table 6). No phosphorous load reductions were assigned to these actions because it was unclear if significant phosphorous cycling occurred.

Table 6: Emergent Vegetation Assessment and Management Projects

Phosphorous cycling was assessed by two means. A literature search indicated that the magnitude of any such cycling would be small. In addition, modeling based on top removal of emergent vegetation demonstrated that phosphorus yield would be three orders of magnitude below phosphorous concentrations that would have any significant phosphorous loading affect. Methods to control Eurasian milfoil, and later, curly leaf pondweed were managed initially by Kootenai County’s Noxious Weed Program and later by the Idaho Department of Agriculture’s (ISDA) Invasive Species Program. Initially Kootenai County’s program addressed milfoil in the lake. However, lobbying by a Hayden Lake resident put the lake high in ISDA’s priorities. The ISDA took over treatment about eight years ago and has controlled both Eurasian milfoil and curly leaf pondweed in the lake through a program of annual invasives census and targeted treatment. Lake monitoring during and after treatment has demonstrated changes in nitrogen compounds, specifically ammonia, in the period after herbicide applications, but no change in either total or ortho-phosphorous concentration. The current evidence indicates that the invasives and their treatment neither adds or detracts to the phosphorous load of the lake.

Based on the project phosphorous load reduction estimates, 240 kilograms of phosphorous per year have likely been removed from Hayden Lake due to completion of projects that can be counted. Cultural changes, like the lack of any forest harvests on the federally managed portion of the watershed and the cessation of most animal husbandry, likely have reduced this load even further. Even with this added reduction it is very doubtful that the calculated reduction of 709 kilograms phosphorous per year has been achieved.

However, the calculated phosphorous reduction in the TMDL (DEQ 2001), assumes the lake preforms in phosphorous addition and reductions like a beaker of water would. A lake is a far more complex water body with its own set of chemical buffering and storage systems, many of which remain poorly understood. For this reason, actual lake total phosphorous monitoring with appropriate confirmatory measurements remains the best assessment of the success of phosphorous reduction efforts.

Another independent means of assessing progress made on lake water quality is through monitoring. The Watershed Improvement District has supported water quality monitoring of the lake since 2016. The

The initial three years concentrated on the lake’s North Arm, north of Henry’s Point, because this area has distinct and very different water quality than the remainder of the lake. During the 2019 monitoring season, the mid-lake station was added back to the monitoring program. The average mid-lake station’s total phosphorous for the years 2019 through 2022 is provided in Table 7. The running average has fallen to 4.6 micrograms per liter. Results from monitoring stations in bays associated with the main pool of Hayden Lake support these results as do lower chlorophyll a measurement. Chlorophyll a is a surrogate measure of algal biomass which, in the main pool of the lake, is dependent on phosphorous concentration. Chlorophyll a ranged from 2.3 to 0.9 micrograms per liter prior to 2009 and now ranges from 0.59 to 0.45 microgram per liter.

Table 7: Measured Average Total Phosphorous Concentration at Mid-Lake Station

Table 8: Measured Average Chlorophyll a concentration at Mid-Lake Station

• Data from 1975(EPA) 1986 (Saltero) 1988-2004 (Black) 2005 and 2006 (Harvey & Walker)

A total maximum daily load (TMDL) limit was developed for Hayden Lake based on a total phosphorous goal of 7 micrograms per liter. A load reduction was designed to reduce total phosphorous concentration from 7.5 micrograms per liter to 7 micrograms per liter. By 2009, a TMDL Implementation plan designating many phosphorous yields reducing projects, and estimating the total phosphorous load (kilograms per year) reduction expected, was established. The Hayden Lake Watershed Association has worked over the ensuing thirteen years with many cooperators and especially, the Hayden Lake Watershed Improvement District, to assure projects were completed. Many projects were completed. This report assesses the load reduction achieved and the attainment of the goal sought. Load reduction that can be accounted for reliably is in the range of 240 kilograms per year, which is far short of the 709 kilograms per year required by the TMDL. However, cultural changes in both forestry and agriculture likely accounted for additional phosphorous load reduction.

Water quality monitoring results acquired over the past four years clearly indicate that the average total phosphorous concentration of the lake has declined nearly 3 ug/L to 4.6 micrograms per liter compared to the near twenty-five-year average of monitoring prior to implementation of the plan (7.5 micrograms per liter). Chlorophyll a measurement, a surrogate for algal productivity which is controlled by

phosphorous availability, supports these results. From the data we can conclude that Hayden Lake is currently fully meeting the water quality goals set for it in the early 1990s and is not water quality limited in its predominant portion, the main pool.

Although the current results and trends are promising, any number of human actions in its watershed might tip the lake’s delicate nutrient balance backwards. All those concerned with the high quality of Hayden Lake and its watershed should remain vigilant and ever ready to take any opportunity to decrease phosphorous loading to the lake.

Saltero R.A., K.R Merrill, M.R. Cather and L.N. Appel 1986. Completion Report for the Investigation entitled Water Quality Assessment of Hayden Lake ID Eastern Washington. Cheney WA 92p.

PHD 1994. PHD, 1994. Hayden Lake Management Plan. Panhandle Health District, 2195 Ironwood Court, Coeur d’ Alene ID 83814. (New address: 8500 N Atlas Road Hayden, ID 83835) 88p.

DEQ 2001. Total Maximum Daily Loads for the Water Quality Limited Water Bodies Located on or Draining to the Rathdrum Prairie (17010305) Idaho Department of Environmental Quality, 2110 Ironwood Parkway, Coeur d’Alene ID. 6p.

HLWA 2009. Hayden Lake Watershed & Lake Management Plan Addendum. Hayden Lake Watershed Association, P.O. Box 3583 Hayden ID 83835. 18p.